Article

Mercury in Petroleum

March 2000
Fuel Processing Technology 63(1):1-27

Authors:

The understanding of geologic mercury has evolved to allow the differentiation of various forms of mercury in hydrocarbon matrices. Combusted hydrocarbons are identified as major anthropogenic sources of mercury emissions to the atmosphere in the United States. There are several mercury species present in crude oil and gas condensates that are seldom accounted for in routine analysis. The distribution of mercury compounds in petroleum varies widely. Crude oil and unprocessed gas condensates contain significant amounts of suspended mercury compounds mainly mercuric sulfide. The dominant dissolved species in petroleum are elemental mercury and ionic halides. While ionic mercury have been found in significant proportions in liquids.

Effects of Mercury Concentration on the Health and Safety of Oil and Gas Workers

Article

Full-text available

Jul 2022

Introduction: The processing of crude oil is characterized by numerous hazards, which have significant health, safety, and environmental impacts on neighboring communities. The occurrence of mercury and its toxic derivatives is considered one of the many negative impacts of oil and gas operations. However, there is limited research on mercury and its negative effects on workers in the Gulf Cooperation Council (GCC) region. This study examines the occurrence, exposure, and symptoms of mercury on the health and safety of oil and gas workers in Oman. It also explores the acute/chronic effects of mercury poisoning on the maintenance and inspection workers, who are more prone to the adverse effects of mercury poisoning during oil and gas operations. Methods: The two-pronged approach of literature review and survey questionnaire was used to deduce the effects of mercury exposure and poisoning using 68 respondents with 1 – 6 years of working experience in the sector. Results: Based on the questionnaire response rate of 72%, the results showed that over 90% of participants had experienced symptoms of elemental, organic, and methyl mercury poisoning. The common symptoms experienced are headaches, insomnia, weakness, hearing impairment, visual and sensory abilities. However, the respondents who experienced methyl mercury (MeHg) symptoms are due to consuming seafood and cigarettes, whereas elemental and organic mercury symptoms are due to oil and gas operations. Conclusion: The findings highlight the need for robust health and safety measures to effectively detect, monitor and eliminate mercury compounds responsible for poisoning maintenance and inspection workers

Distribution and environmental geochemical indices of mercury in tar contaminated beaches along the coast of Qatar

Article

Full-text available

Feb 2022

The current study aimed to gauge total mercury (THg) concentration and the environmental geochemical indices in tarmat contaminated sediments and test their presence in targeted coastal species. Layers of hard asphalt-like tarmats and sediment samples were collected from 34 sites along the coast of Qatar. The mean concentration of THg in tarmat-sediment mixture is 89 ± 20 ng⋅g − 1. THg concentration varies significantly between the northern and eastern coasts. Geographically, sampling area were divided into four zones according to the relative closeness with low to serious potential ecological risk index (E r), moderate pollution load index (PLI), moderate Geoaccumulation index (I geo), and no toxic risk (TRI) trending as Northern (Zones 4, 3) > NorthEastern (Zone 1) > Western (Zone 2) coasts. Three biota classes (Gastropoda, Bivalvia, and Crustacea) were sampled on the tarmat which the hermit crab (Clibanarius signatus) from Ras Rakan island obtained the highest THg (977 ng⋅g − 1) and BSAF (29.70).

Standard methods used for mercury analysis in the oil and gas industry

Article

Full-text available

Jan 2021

Wong Sharizal Mohd Azam Shah

Mercury is a contaminant found in a variety of hydrocarbons and non-hydrocarbon streams in the oil and gas industry. Quantification of mercury is an integral part to protect processing units especially those with aluminium components and to safeguard personnel from unwanted exposure to mercury. Although mercury is one of the many impurities in oil and gas, its impact is diverse, and this drives the need to adequately quantify the amount of mercury in the process stream as a first line of defence and to make informed decisions on mitigation. The various types of standard methods available for mercury analysis are listed and classified in this literature based on sample phase for hydrocarbon and non-hydrocarbon samples. Different types of mercury analysis such as total mercury, mercury grouping and mercury speciation are also briefly explored to determine which is best for intent of use. Measurement techniques involving different detectors and their respective detection limits are listed with specific attention provided to atomic absorption and atomic fluorescence. The diverse adoption of various mercury analysis across the hydrocarbon value chain will need to be fit for purpose and meet the analytical requirements of the test conducted.

Lactational Exposure of Human Infants to Metal (loid)s: A Comparison of Industrial and Urban Inhabitants in North of the Persian Gulf

Article

Full-text available

Aug 2023
BIOL TRACE ELEM RES

In this study, postnatal metal (loid)s (MLs) exposure was compared between the petrochemical and gas area of Asaluyeh (PGA) and urban area of Kaki (UA) in Bushehr province, Iran. Two hundred human breast milk (BM) samples from the industrial and urban areas were analyzed for MLs using Inductivity Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Boron (B), copper (Cu), iron (Fe), and nickel (Ni) were found at the highest levels in both study areas. Adjusted multiple linear regression models revealed that the mean concentration of total MLs in BM samples collected from the PGA was statistically significantly greater than that of the UA (655.85 vs. 338.17 µg/L). Also, the mean concentrations of all detected MLs in BM samples collected from the PGA were statistically significantly higher than those collected from the UA. The hazard index (HI) of combined MLs in the PGA and UA illustrated non-cancer risk for infants. Lead (Pb) and chromium (Cr) in the PGA and Cr in the UA showed the risk of cancer. So it can be concluded that nursing infants from an industrial area are most at risk for MLs exposure during entire lactation course than those from an urban area.

Encapsulation of activated carbon into calcium alginate microspheres toward granular-activated carbon adsorbents for elemental mercury capture from natural gas

Article

Full-text available

Jun 2023
ENVIRON SCI POLLUT R

Activated carbon (AC) is an effective adsorbent for removing environmental pollutants. However, the traditional powder form of AC shows difficulty in handling during application which widely limits its utilization on the industrial scale. Herein, to avoid such limitation, traditional AC powder was encapsulated into calcium alginate (CA) microspheres. Calcium alginate/activated carbon (CAA) composite microspheres were prepared via cross-linking of sodium alginate/activated carbon composite solutions in a calcium chloride solution. Furthermore, in order to boost adsorption affinity of CAA composite microspheres toward elemental mercury (Hg°), ammonium iodide (NH4I)-treated calcium alginate/activated carbon (NCA) composite microspheres were obtained by a simple impregnation method using NH4I treatment. The morphological, structural, and textural properties of the microspheres were characterized and their Hg° adsorptive capacity was tested at different temperatures. Interestingly, the maximum adsorption capacity of NCA adsorbent composite microspheres was determined as 36,056.5 μg/g at a flow rate of 250 mL/min, temperature of 25 °C, and 500 μg/Nm³ of Hg° initial concentration. The Gibbs free energy (ΔG°) for NCA adsorbent composite microspheres varied from − 8.59 to − 10.54 kJ/mol indicating a spontaneous adsorption process with an exothermic nature. The experimental Hg° breakthrough curve correlated well with Yoon‒Nelson and Thomas models. The breakthrough time (tb) and equilibrium time (te) were found to be 7.5 days and 23 days, respectively. Collectively, the findings of this work indicate a good feasibility of using NCA composite microspheres as potential adsorbents for removing Hg° from natural gas. Graphical Abstract

Mercury isotope variation during organic matter maturation to petroleum

Article

Full-text available

Dec 2022
CHEM GEOL

Although both sedimentary rocks and petroleum generally contain detectable levels of Hg, the characteristics of Hg isotope fractionation and its transformation from biomass to sedimentary rocks to petroleum have not been sufficiently investigated to date. Here, we report Hg contents and isotope compositions in source rocks and crude oils from the Paleogene of the Bohai Bay Basin and in source rocks from the Permian and Jurassic of the Sichuan Basin in China. Our analysis made use of an improved crude oil Hg pre-concentration system involving pyrolytic cracking and KMnO4/H2SO4 Hg trapping to analyze Hg fractionation during organic matter maturation to petroleum. Positive mass-independent fractionation (MIF) signatures of Hg isotopes were detected in the source rocks, with Δ199Hg ranging between 􀀀 0.04‰ and + 0.48‰ (mean + 0.12 ± 0.12‰), which is significantly different from the negative Δ199Hg of terrestrial non-source rocks. Positive Hg-MIF signatures were detected in the crude oil, with Δ199Hg ranging between +0.04‰ and + 0.21‰ (mean + 0.13 ± 0.06‰). We propose a model of Hg isotopic fractionation related to organic matter history. From organic matter to source rock, Hg system variations are attributed to endogenic (i.e., photoreduction) and exogenic processes (i.e., terrestrial, magmatic and hydrothermal Hg inputs). From source rock to petroleum, Hg is mobilized during hydrocarbon migration, a process that occurs with MDF but without significant MIF.

A Review of Mercury Waste Management in the ASEAN Oil and Gas Industry

Article

Jan 2023

Given the annual generation of huge quantities of mercury waste worldwide, mercury exposure is a universal issue. Mercury waste from the oil and gas industry should be of concern, owing to the presence of mercury during the whole oil and gas life cycle, as well as the industry’s importance and magnitude. Particular attention should be given to mercury waste from the Association of Southeast Asian Nations (ASEAN) oil and gas industry because of the high mercury concentrations in the regional petroleum deposits and the upcoming growth of the upstream and downstream subsectors. Therefore, this study aims to explore: (1) how mercury waste from the ASEAN oil and gas industry is managed and (2) the extent to which waste management facilities in the ASEAN can handle such waste. The paper starts with a description of some mercury forms occurring in oil and gas operations and the current situation of the ASEAN oil and gas sector. It then presents the legal frameworks and facilities for mercury waste management in the region and ends with a case study analysis of Best Mercury Technology (BMT) Thailand—a mercury waste management facility. The findings show that most countries lack specific laws on mercury waste management, while some have not legally identified mercury waste from the oil and gas industry and set thresholds for determining mercury waste as well as specific mercury emission standards for oil and gas activities. Other challenges include the lack of proper mercury waste management facilities or facilities that cannot recover mercury from the waste in some nations, including those having a strong oil and gas industry. The case study analysis demonstrates that BMT Thailand’s operations adhere to the national legal requirements as well as many international standards and conventions, indicating the availability of a world-class facility in the ASEAN to cater for the regional demand.

Calculating the chemical and phase equilibria of mercury in natural gas

Article

May 2021
FLUID PHASE EQUILIBR

Elemental mercury occurs naturally in traces in fossil fuels, such as crude oil and natural gas. Knowledge of the mercury solubility in natural gas is critical in order to avoid mercury drop-out, which can cause health, safety, and environmental issues during operation, maintenance, or equipment decommissioning. Moreover, mercury transformation to other forms, such as solid HgS, further complicates the management of mercury levels in a processing plant, as well as the design of mercury removal processes. Therefore, thermodynamic models and algorithms that can accurately describe the chemical and phase equilibria of mercury in natural gas are of paramount importance. In this work, a multiphase flash algorithm is implemented for calculating the solubility of elemental mercury in typical natural gas fluids. The algorithm can handle three- and even four-phase systems (vapor-liquid hydrocarbon-water-mercury), while a free-mercury assumption is proposed to accelerate solution speed. In addition, a simultaneous chemical and phase equilibrium algorithm is employed for studying a theoretical reaction between mercury and H2S that can lead to solid HgS formation in natural gas. Both algorithms are coupled with the UMR-PRU model, and new interaction parameters are estimated for groups Hg and H2S with CO2, N2, and hydrocarbons, yielding very satisfactory results. Despite the lack of experimental data for comparison, the study of mercury solubility and reaction in natural gas with the proposed algorithms leads to very useful qualitative results, which agree with field observations.

Mercury partitioning in oil and gas production systems - design optimisation and risk mitigation through advanced simulation

Article

Jan 2020

Operators are increasingly producing fields with challenging operational environments, including fluids with higher concentrations of mercury. Mercury is harmful to personnel and the environment and contaminates most of the production plant that it contacts through physical adsorption, potentially creating hazardous wastes through the operating lifetime and subsequent decommissioning. The assessment of mercury removal locations requires careful consideration at the design stage. Mercury exists in various chemical forms that readily partition between streams in the production process. Mercury partitioning simulations are an essential step in managing the operational, safety, environmental, production and decommissioning risks associated with mercury. Accurate assessment of mercury species during welltests is an essential step towards successful mercury risk management; providing the basis to model partitioning into vapour, liquid, aqueous and solid phases through production. Adsorption modelling is also necessary to understanding the propagation of mercury through offshore and onshore systems, identifying release points to the environment. Only once form, flow and accumulation locations are understood, can the adequate design of mercury removal facilities be confidently completed. Experience in thermodynamic modelling and verification through laboratory research and plant analysis is required to fully understand modelling limitations, capabilities and applications to proposed or existing infrastructure. Changes in inlet stream conditions may affect propagation of mercury through an operating plant thus the influence of predicted conditions through the full life of the field should be considered.

Poly(ethylene glycol) Diacrylate Hydrogels Doped with Silver Nanoparticles for Optical Sensing and Removing Hg(II) Ions from Water

Article

Full-text available

Oct 2023

In this study, an innovative approach for the integration of silver nanoparticles (AgNPs) into poly(ethylene glycol) diacrylate (PEGDA) hydrogels is described. The composite material is the first in the literature where AgNPs were doped into PEGDA using photo-polymerization technique for a double function: detection and elimination of Hg(II) ions from water. The doping of AgNPs into PEGDA-based matrices was performed using a photo-polymerizable process. The Hg(II) sensing properties were explored in a concentration range from 0 to 20 mg/L. Notably, a linear dependence was observed up to 1 mg/L, accompanied by a limit of detection of 0.3 mg/L. Beyond sensing, the efficiency of the doped hydrogel in removing Hg(II) ions was also investigated and compared with an undoped PEGDA matrix. The outcome highlighted an enhanced removal efficiency of the doped material of approximately 23%. Finally, the experimental data suggested that the interaction between Hg(II) ions and the modified hydrogel adhered to the Langmuir isotherm model, which suggested that chemisorption was the driving mechanism of the adsorption of Hg(II) onto the modified hydrogel matrix.

Multivariate analysis of trace elements in starry sturgeon (Acipenser stellatus) spine in different areas of the Caspian Sea

Article

Full-text available

Jul 2023

Sturgeons are one of the most valuable species in the Caspian Sea. There, habitation of the seabed and feeding on benthic organisms makes this species a good indicator of trace element status. Thus, we aimed to determine the concentrations of 31 trace elements in the pectoral fin spine of starry sturgeons, and to evaluate the relationships between the different chemical elements. For this, a total of 40 starry sturgeons were obtained in a repopulation programme from the coastal waters north and south of the Caspian Sea. First, we used a multivariate analysis of variance to establish the differences between zones. Later, to assess relationships between trace elements, we used principal component analysis and cluster analysis. In general, the concentration of many trace elements did not vary between zones. However, some elements, including mercury or arsenic, were found in the north areas at higher concentrations.

The impact of corrosion on the adsorption of gaseous Hg0 onto the surface of steels: Implications for decommissioning in the oil and gas industry

Article

Full-text available

Jul 2023
J HAZARD MATER

The rate of decommissioning of global oil and gas production facilities will accelerate over coming decades, as mature developments reach the end of use, and consumers transition towards renewable energy. Decommissioning strategies should include thorough environmental risk assessments which consider contaminants which are known to be present in oil and gas systems. Mercury (Hg) is a global pollutant that occurs naturally in oil and gas reservoirs. However, knowledge of Hg contamination in transmission pipelines and process equipment is limited. We investigated the potential for accumulation of Hg0 within production facilities, particularly those transporting gases, by considering the deposition of Hg onto steel surfaces from the gas phase. Following incubation experiments in a Hg saturated atmosphere; fresh API 5L‐X65 and L80–13Cr steels were found to adsorb 1.4 × 10−5 ± 0.04 × 10−5 and 1.1 × 10−5 ± 0.04 × 10−5 g m−2, respectively, while corroded samples of the same steels adsorbed 0.12 ± 0.01 and 0.83 ± 0.02 g m−2; an increase in adsorbed mercury by four orders of magnitude. The association between surface corrosion and Hg was demonstrated by laser ablation ICPMS. The levels of Hg measured on the corroded steel surfaces indicates a potential environmental risk; therefore, mercury speciation (including the presence of ß-HgS, not considered in this study), concentrations and cleaning methods should be considered when developing oil and gas decommissioning strategies.

An approach to assess potential environmental mercury release, food web bioaccumulation, and human dietary methylmercury uptake from decommissioning offshore oil and gas infrastructure

Article

Full-text available

Mar 2023
J HAZARD MATER

Subsea pipelines carrying well fluids from hydrocarbon fields accumulate mercury. If the pipelines (after cleaning and flushing) are abandoned in situ, their degradation may release residual mercury into the environment. To justify pipeline abandonment, decommissioning plans include environmental risk assessments to determine the potential risk of environmental mercury. These risks are informed by environmental quality guideline values (EQGVs) governing concentrations in sediment or water above which mercury toxicity may occur. However, these guidelines may not consider e.g., the bioaccumulation potential of methylated mercury. Therefore, EQGVs may not protect humans from exposure if applied as the sole basis for risk assessments. This paper outlines a process to assess the EQGVs' protectiveness from mercury bioaccumulation, providing preliminary insights to questions including how to (1) determine pipeline threshold concentrations, (2) model marine mercury bioaccumulation, and (3) determine exceedance of the methylmercury tolerable weekly intake (TWI) for humans. The approach is demonstrated with a generic example using simplifications to describe mercury behaviour and a model food web. In this example, release scenarios equivalent to the EQGVs resulted in increased marine organism mercury tissue concentrations by 0-33 %, with human dietary methylmercury intake increasing 0-21 %. This suggests that existing guidelines may not be protective of biomagnification in all circumstances. The outlined approach could inform environmental risk assessments for asset-specific release scenarios but must be parameterised to reflect local environmental conditions when tailored to local factors.

Preindustrial levels and temporal enrichment trends of mercury in sediment cores from the Gulf of Thailand

Article

Full-text available

Jan 2023
ENVIRON GEOCHEM HLTH

Four sediment cores in the middle of Gulf of Thailand (GOT) and one core close to Bang Pakong River mouth were examined for total mercury (T-Hg) using direct thermal decomposition coupled with the atomic absorption spectrometry (DTD-AAS) method and acid digestion (acid-CVAAS) method, and sediment chronologies using ²¹⁰Pb dating. T-Hg in the river mouth core ranged 44.49–52.76 µg/kg and higher than the cores from the middle of GOT (18.26–36.68 µg/kg). The age span obtained from the cores dated back to the 1940s with the sediment accumulation rates of 0.15–0.76 cm/year. The preindustrial levels of T-Hg showed an initial slow increase followed by a rapid elevation since the 1960s which marked the start of the industrialized period in the country. To this end, we posit that T-Hg in the GOT sediment can be attributed to not only land-based sources but also offshore activities including petroleum exploration and frequent accidental oil spills.

Applications of agricultural residue biochars to removal of toxic gases emitted from chemical plants: A review

Article

Jan 2023
SCI TOTAL ENVIRON

Crop residues are representative agricultural waste materials, massively generated in the world. However, a large fraction of them is currently being wasted, though they have a high potential to be used as a value-added carbon-rich material. Also, the applications of carbon-rich materials from agricultural waste to industries can have economic benefit because waste-derived carbon materials are considered inexpensive waste materials. In this review, valorization methods for crop residues as carbon-rich materials (i.e., biochars) and their applications to industrial toxic gas removals are discussed. Applications of crop residue biochars to toxic gas removal can have significant environmental benefits and economic feasibility. As such, this review discussed the technical advantages of the use of crop residue biochars as adsorbents for hazardous gaseous pollutants and greenhouse gases (GHGs) stemmed from combustion of fossil fuels and the different refinery processes. Also, the practical benefits from the activation methods in line with the biochar properties were comprehensively discussed. The relationships between the physico-chemical properties of biochars and the removal mechanisms of gaseous pollutants (H2S, SO2, Hg0, and CO2) on biochars were also highlighted in this review study. Porosity controls using physical and chemical activations along with the addition of specific functional groups and metals on biochars have significantly contributed to the enhancement of flue gas adsorption. The adsorption capacity of biochar for each toxic chemical was in the range of 46-76 mg g-1 for H2S, 40-182 mg g-1 for SO2, 80-952 μg g-1 for Hg0, and 82-308 mg g-1 CO2, respectively. This helps to find suitable activation methods for adsorption of the target pollutants. In the last part, the benefits from the use of biochars and the research directions were prospectively provided to make crop residue biochars more practical materials in adsorption of pollutant gases.

Employing of 2-Acetylpyridine Based Chalcone as Hg2+ Sensing Material: Experimental and Theoretical Examination

Article

Full-text available

Oct 2022

This study reports the evaluation of 2-acetylpyridine based chalcone structure as a useful sensing material for Hg2+ ion detection by the means of UV-visible spectroscopy. In this context, firstly, the most common twenty metal ions were treated by the chalcone structure which was synthesized from 2-acetylpyridine and 4- diphenylaminobenzaldehyde according to the known procedures. As result, the studied chalcone compound exhibited good sensing activity towards Hg2+ ion in acetonitrile/water medium with significant red-shift phenomenon. In addition, some photophysical/electronic parameters of the chalcone and its Hg2+ complex were determined experimentally and theoretically. B3LYP, PBE0 methods and SVP, TVZP, and TVZPP basis sets were used for theoretical calculations in acetonitrile media. Finally, experimental results were explained and the proposed sensing mechanism was supported via density functional theory (DFT) outputs.

Current understanding of the ecological risk of mercury from subsea oil and gas infrastructure to marine ecosystems

Article

Jun 2022

Many oil and gas fields are nearing production cessation and will require decommissioning, with the preferred method being complete infrastructure removal in most jurisdictions. However, decommissioning in situ, leaving some disused components in place, is an option that may be agreed to by the regulators and reservoir titleholders in some circumstances. To understand this option's viability, the environmental impacts and risks of any residual contaminants assessed. Mercury, a contaminant of concern, is naturally present in hydrocarbon reservoirs, may contaminate offshore processing and transmission infrastructure, and can biomagnify in marine ecosystems. Mercury's impact is dependent on its speciation, concentration, and the exposure duration. However, research characterising and quantifying the amount of mercury in offshore infrastructure and the efficacy of decontamination is limited. This review describes the formation of mercury-contaminated products within oil and gas infrastructure, expected exposure pathways after environmental release, possible impacts, and key research gaps regarding the ecological risk of in situ decommissioned contaminated infrastructure. Suggestions are made to overcome these gaps, improving the in situ mercury quantification in infrastructure, understanding environmental controls on, and forecasting of, mercury methylation and bioaccumulation, and the cumulative impacts of multiple stressors within decommissioned infrastructures.

Reusable Extractant and Direct Catalytic Mediation of Water/Oil/Chlorodifluoromethane Nano-Emulsion in Natural Gas Condensate for Efficient Conversion of Chloride Impurities Into the Dicopper Chloride Trihydroxide Nanoparticles

Article

Full-text available

Apr 2022

This research introduces an oil-in-water (O/W) nano-emulsion (oil-water- CHClF 2 ) as the reusable extractant phase using liquid–liquid extraction methodology for the removal efficiency of Cl− and Hg(0) [between 90% and ∼100%, deepening on the nature of the natural gas condensate (NGC)] at a brief separation time (<3.0 min). The achieved safety of the NGC using this nano-emulsion results in efficient reduction in the corrosion rate during testing iron-based fragments (vs. the untreated ones as controls) and increase in the NGC economic value. Another advantage of the synthesized nano-emulsion is its capability and catalytic mediating behavior to efficiently separate and synthesize highly pure dicopper chloride trihydroxide nanoparticles. The synthesized nanoparticles were characterized by different analytical methods such as Fourier transform infrared spectrometry, X-ray diffraction, X-ray photoelectron spectrometry, and direct visualization by some electron microscopies. Direct synthesis, fast synthetic time (<3.0 min), high purity (>99%), and scalability are the main advantages of this synthetic method. This nanoparticle is not only safe but also is efficiently applicable in different industries, especially as an eco-friendly agricultural pesticide for different plants and tress such as pistachio. Consequently, this method is accepted as direct, simple, low-cost, and scalable conversion of some upstream industries with the downstream ones. All these possibilities are attributed to the intermediate transport properties of the introduced O/W nano-emulsion. At this condition, this reagent plays role as a recycled motor for the NGC purification and conversion of these impurities into the safe and usable products. To the best of knowledge, this research is considered as the first report that shows application of this O/W medium for both chloride and mercury removal from the NGC and its direct use as top element in the synthesis of eco-friendly nanoparticles. This system is applicable in some parts of the fuel and oil centers of the “Middle East.”

Opportunities and challenges for the application of post-consumer plastic waste pyrolysis oils as steam cracker feedstocks: To decontaminate or not to decontaminate?

Article

Full-text available

Feb 2022
WASTE MANAGE

Thermochemical recycling of plastic waste to base chemicals via pyrolysis followed by a minimal amount of upgrading and steam cracking is expected to be the dominant chemical recycling technology in the coming decade. However, there are substantial safety and operational risks when using plastic waste pyrolysis oils instead of conventional fossil-based feedstocks. This is due to the fact that plastic waste pyrolysis oils contain a vast amount of contaminants which are the main drivers for corrosion, fouling and downstream catalyst poisoning in industrial steam cracking plants. Contaminants are therefore crucial to evaluate the steam cracking feasibility of these alternative feedstocks. Indeed, current plastic waste pyrolysis oils exceed typical feedstock specifications for numerous known contaminants, e.g. nitrogen (∼1650 vs. 100 ppm max.), oxygen (∼1250 vs. 100 ppm max.), chlorine (∼1460 vs. 3 ppm max.), iron (∼33 vs. 0.001 ppm max.), sodium (∼0.8 vs. 0.125 ppm max.) and calcium (∼17 vs. 0.5 ppm max.). Pyrolysis oils produced from post-consumer plastic waste can only meet the current specifications set for industrial steam cracker feedstocks if they are upgraded, with hydrogen based technologies being the most effective, in combination with an effective pre-treatment of the plastic waste such as dehalogenation. Moreover, steam crackers are reliant on a stable and predictable feedstock quality and quantity representing a challenge with plastic waste being largely influenced by consumer behavior, seasonal changes and local sorting efficiencies. Nevertheless, with standardization of sorting plants this is expected to become less problematic in the coming decade.

Mercury Exposure in Artisanal Mining: Assessing the Effect of Occupational Activities on Blood Mercury Levels Among Artisanal and Small-Scale Goldminers in Ghana

Article

Full-text available

Nov 2021
BIOL TRACE ELEM RES

A cross-sectional survey of 425 male artisanal and small-scale goldminers (ASGM) was conducted to examine the relationship between the occupational activities of the miners and their blood mercury levels while controlling for relevant biosocial and socio-cultural factors. The data was subjected to descriptive and inferential statistics. Initial findings showed that 43.29% of the ASGM miners had blood mercury levels above the occupational exposure threshold. Among the occupational factors , ASGM miners who amalgamate gold, burn amalgam, and ASGM miners who smelt gold were 2.260, 1.881, and 2.094 times respectively more likely to have high blood mercury levels as compared to ASGM miners who did not carry out these activities. Also, ASGM miners who suck excess mercury with their mouth (OR = 0.197, p < 0.001) were less likely to have high blood mercury levels. For the biosocial and socio-cultural attributes, high blood mercury levels was less likely among older ASGM miners (OR = 0.507, p < 0.05). Inversely, high blood mercury levels was more likely among ASGM miners who are married (OR = 1.627, p < 0.05), ASGM miners with junior (OR = 2.240, p < 0.001) and senior (OR = 1.575, p < 0.05) high school education, and ASGM miners who have 6-10 years (OR = 3.802, p < 0.001) and above 10 years (OR = 2.591, p < 0.001) work experience. ASGM miners who amalgamate gold, burn amalgam, and smelt gold are exposed to mercury and are at risk of mercury poisoning. This could, however, be minimized with the right capturing devices and personal protective equipment. This notwithstanding, unsafe, and unsustainable occupational practices such as working in mercury contaminated water and sucking excess mercury with the mouth should be discouraged.

A review of the geochemical changes occurring during metamorphic devolatilization of metasedimentary rocks

Article

Feb 2021
CHEM GEOL

Aleksandr Stepanov

Redistribution of elements by fluids produced by the metamorphic devolatilization (MDV) of sedimentary rocks is one of the major processes responsible for the differentiation of the crust. Comparison of compositions of rocks with similar original composition (protolith) with increasing metamorphic grades is the principal method of observation and quantification of the mass transfer caused by the loss of fluids. This work summarises observations from metamorphic complexes covering a wide range of PT conditions and lithologies that have been studied worldwide for the chemical effects of metamorphism. The metamorphic complexes range from coherent sedimentary sequences where the same stratigraphic horizons have been traced across different metamorphic zones, to folded turbidite piles and accretionary prisms where terranes with different peak PT conditions are divided by tectonic boundaries. The geochemical changes caused by the MDV are different in different complexes. Some elements are depleted in almost all complexes, whereas others are affected only in exceptional cases. The major elements, and the majority of lithophile and siderophile elements are not depleted by metamorphic devolatilization. Mercury is the first element to be lost from sediments at conditions of sub-greenschist metamorphism, which may coincide with the loss of Cd. Arsenic depletion is almost universal in metamorphic rocks, and is correlated with the decomposition or recrystallisation of sedimentary pyrite during greenschist facies metamorphism, where it can occur at similar temperatures both in regional metamorphic rocks and in subduction zone metamorphism. Gold, Sb, Ag, and W depletion are documented to coincide with As loss in regional metamorphic complexes. The content of C and S changes in some cases but remain conserved in others. Base metals including Cu, Pb and Zn are typically conserved during metamorphic devolatilization but exceptions have also been reported, where these metals are progressively depleted during upper greenschist and lower amphibolite facies metamorphism. Chlorine can be extracted by the metamorphic devolatilization in some metamorphic sequences, whereas F is conserved. The majority of lithophile elements show conservative behaviour during metamorphic devolatilization including REE, HFSE, and LILE, with the exceptions of Cs, N, U, and B in some complexes, where the depletion in some cases is associated with dehydration and in others possibly with the beginning of anatexis. The loss of hydrous fluids may be limited during high-pressure metamorphism and in sediments with abundant carbonates; under these conditions depletion of trace elements can be insignificant. Metamorphic devolatilization has the potential to be an efficient and powerful mechanism for the concentration of dispersed elements into ore-grade mineralisation. The connection between devolatilization and the origin of orogenic gold deposits is the most established in this regard, and some other deposit types are likely related to specific types of metamorphic fluids.

Bioaccumulation of heavy metals (Hg, Cd and Ni) by sentinel crab (Macrophthalmus depressus) from sediments of Mousa Bay, Persian Gulf

Article

Dec 2019

The presence of heavy metals (HMs) in the environment can increase their risk of transfer to the food chain. The present study was conducted to investigate the bioaccumulation of HMs including Hg, Cd and Ni in soft and hard tissues of sentinel crab (Macrophthalmus depressus Rüppell, 1830) in sediments of Mousa Bay in northwest of the Persian Gulf. The average (mean ± SD) amounts of Hg, Cd and Ni in the sediments were 6.27 ± 3.66, 3.8 ± 1.48 and 71.6 ± 5.09 μg/g, whereas the relevant amounts for soft tissues were 6.16 ± 4.64, 3.3 ± 1.7 and 19.7 ± 3.96 μg/g, and for hard tissues were, 2.9 ± 1.67, 3.5 ± 1.35 and 10.44 ± 3.1 μg/g, respectively. Accordingly, soft tissues of the crab could be suitable bioindicators of Hg and Cd, whereas the hard tissues could be used as Cd bioindicator. Since the bioaccumulation of Ni was the most, it might have a higher risk among the metals to enter the food chain in the region.

Syngas Cleaning Technologies in Gasification Process for Downstream Applications

Chapter

Oct 2023

Syngas (CO and H2) are cleaner and environmental friendly fuel as compare to fossil fuels. Generation of syngas using the availability of vast variety of feedstock (coal, biomass, natural gas, municipal solid waste etc.) make it lucrative option as an alternative to substitute for the conventional liquid fuels and other chemicals. In the industry, the word “syngas” is frequently used to refer the product gas from the gasification and reforming process from solid (coal, biomass, municipal waste, petcoke) and gaseous carbonaceous (natural gas) feedstocks respectively. During gasification process various elements like sulphur, nitrogen, halogen and alkali metals present in carbonaceous feedstock get converted to contaminants and generally referred as “impurity”. The concentrations of these impurities are heterogeneous and depend strongly on the carbon source, and gasification operating parameter (e.g. pressure, temperature, residence time, types of gasifier). Those impurities can lower the activity of almost any type of catalytic reactions, so it is essential to remove them to meet the downstream process specifications. The presence of these pollutants in syngas causes a variety of technical and operational challenges, including equipment corrosion by hydrogen sulphide, and catalyst deactivation (tar, hydrogen sulphide, ammonia, Hydrogen chloride, and trace metals). Syngas cleaning methods are comprehensively reviewed in the present paper.

Early and Accurate Quantification of Mercury Contaminant Levels in Gas-Condensate Reservoirs

Conference Paper

Oct 2023

Mercury is a trace contaminant present in natural gas and condensates. Production facilities must be designed to remove anticipated mercury contamination in natural gas streams to meet process safety, health, environmental, regulatory and sales requirements. Early and accurate quantification of mercury concentration levels is therefore critical for the safe and economic development of gas resources. This paper introduces reservoir fluid sampling and mercury analysis techniques demonstrated to accurately determine the mercury concentrations in gas-condensate reservoirs. The mercury analysis of reservoir fluid samples acquired with formation sampling tools often misrepresent mercury concentration levels measured later during production. This is due to the highly volatile and reactive nature of mercury, particularly with uncoated metallic surfaces. Laboratory experiments were conducted to develop procedures for accurate and repeatable analysis of mercury concentrations in gas sampling systems. Methane was contaminated with precise concentrations of mercury to facilitate a range of experiments examining both the contamination and scavenging behaviour of mercury in sample chambers. Uncontaminated methane was used as a baseline for background testing sample chambers and laboratory equipment. The experiments identified the presence of residual mercury contamination in sample chambers and laboratory equipment previously exposed to mercury. Cleaning procedures involving the thermal desorption of residual mercury were developed and proven to ensure sampling chambers and laboratory equipment were free of any mercury contamination. Without applying cleaning procedures, any residual mercury would contribute to incorrectly overpredicting the mercury concentrations of reservoir fluids captured in the sample chambers. Subsequent experiments showed that even inert coatings do not completely prevent mercury adsorption to internal metallic chamber walls. Heating the sample chambers to 140 °C was found to release most of the adsorbed mercury back into the gas phase, with a wash procedure required to recover all the remaining mercury and avoid incorrectly underpredicting the actual mercury concentration levels due to scavenging. By implementing a combination of procedural changes, sampling tool modifications and improved measurement techniques, it is possible to acquire reservoir fluid samples with formation sampling tools and accurately measure mercury concentrations representative of that produced from the reservoir. The case study of a gas-condensate field is used to demonstrate that by following the novel techniques introduced in this paper, reservoir fluid samples acquired from wells using formation sampling tools and analysed for mercury can accurately represent the mercury concentration levels measured later during the production phase. Processing facilities can then be appropriately designed or modified early in the field development lifecycle to remove any anticipated mercury in natural gas process streams.

Novel Compact Integrated Cyclone and Filtration System for Solid Mercury Removal

Conference Paper

Oct 2023

Mercury presence in produced fluid poses serious issues to gas production process due to HSSE risk, process disturbance and product quality for export. Mercury management is conducted based on type of mercury presence, for instance elemental mercury and solid mercury. For elemental mercury, adsorbent is typically being used, while solid mercury removal is managed via filtration. However, established mercury removal strategy is limited to "single" phase (gas, hydrocarbon liquid, water) thus can only be carried out post phase separation, while there is no available mercury removal technology for full well stream (FWS) treatment as early as at the wellhead. A novel compact separation concept based on integrated cyclone and filtration design for removing solid mercury in gas dominant full well stream was developed, to allow for flexibility in implementation location (from multiphase at wellhead to single phase post separation) and achieve reliable and consistent separation performance at 1 μm particulate size. Testing with solid mercury particles demonstrated the technology feasibility in removing particles of 1 μm and larger, where particles of 1 μm and larger was not detected by the high-speed imaging camera used at the clean fluid outlet for solid monitoring. CFD simulation conducted provided reference on the feasibility of the technology based on fluid regime and dynamics in removing solid mercury at test conditions, as well as at intended site conditions. A reliable and flexible solution is key to ensure effective contaminant management from the target production, and safeguarding production loss due to contaminant presence in the long run.

New upstream solution for mercury removal from petroleum condensate via HFMC: Thermodynamics, kinetics, DFT and mass transport

Article

Aug 2023
HYDROMETALLURGY

Fluid inclusion and H–O-S-Pb isotope constraints on the origin of carbonate-hosted Hg-Sb mineralization at Gongguan, central China

Article

Full-text available

Jul 2023
MINER DEPOSITA

The Gongguan deposit in southern Qinling district, central China, is characterized by a Hg and Sb metal association, with proven reserves of 7,543 t Hg and 17,100 t Sb. The Hg-Sb mineralized veins are primarily hosted by local Lower Devonian dolomite. Three primary paragenetic stages have been identified, including (I) pyrite-dolomite-quartz, (II) stibnite-cinnabar-quartz-calcite and (III) post-ore calcite. Dominant mercury and antimony mineralization occurred in stage II. Fluid inclusion microthermometry of quartz and calcite reveal that the Hg-Sb mineralization is associated with a low temperature (142° to 240 °C) and low salinity (< 8.6 wt% NaCl equivalent) fluid, belonging to a H2O-NaCl ± CO2 system. The H–O isotope compositions (δDH2O = −84 to −63‰, δ¹⁸OH2O = 1.3 to 12.7‰) of the hydrothermal fluid suggest a mixture of metamorphic fluid and meteoric water. In situ sulfur isotope results of cinnabar (δ³⁴S = 3.4 to 14.5‰), stibnite (δ³⁴S = 4.9 to 10.5‰) and pyrite (δ³⁴S = 3.8 to 5.4‰) indicate sulfur sources from decomposition of diagenetic pyrite and/or the thermochemical sulfate reduction in local sedimentary rocks. In situ obtained ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios (18.006 to 18.362, 15.445 to 15.610 and 37.871 to 38.288, respectively) of stibnite and pyrite substantially differ from those for the regional Carlin Au-Sb and SEDEX Pb–Zn ore deposits. The lead isotope results indicate that the underlying Paleozoic (Silurian to Cambrian) strata and Precambrian metamorphic basement supplied substantial metals for the studied Hg-Sb deposit, whereas the host Devonian carbonates did not contribute significant metals. In summary, we propose that fluid mixing between metamorphic fluid and meteoric water was the main cause for carbonate-hosted Hg-Sb deposition at Gongguan, which reduced the stibnite solubility, oxidized mercury (Hg⁰ to Hg²⁺), favoring the process of dedolomitization.

Mercury management during decommissioning: predicting accumulation and mitigating risk of release

Article

May 2023

In 2021, Australia ratified the Minamata Convention on mercury, an international treaty that seeks to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. Mercury is a highly toxic metal with damaging effects even at extremely low concentrations. Decommissioning of pipelines and topside equipment that have processed fluids containing even trace quantities of mercury may create significant hazards to personnel and the environment. This paper considers the various mechanisms by which mercury accumulates in process systems and addresses important considerations, to mitigate the risks of mercury release during decommissioning. Where production fluids contain trace quantities of hydrogen sulfide, in addition to mercury, then mercury can react with compounds in scale layers to form mercury sulfide deposits, incorporated within the scale. In addition, mercury may also physically adsorb onto steel surfaces and within porous scale layers, and if mercury condensation occurs then amalgams may form with susceptible metals. Where pipelines are coated or clad, mercury can still be physically or chemically adsorbed onto the pipeline at weld joints. Production fluids containing mercury may also permeate through spiral-wound metal carcass layers of flexible flowlines. Mercury trapped in the carcass voids may be retained after flushing, to be released later during recovery operations, presenting a risk to personnel and the environment. Estimating the quantity, forms and areas contaminated with mercury compounds supports future decommissioning strategy development and select mitigation measures that reduce risks to personnel and the environment to as low as reasonably practicable.

Penyingkiran Merkuri Dari Minyak Mentah Berat: Konversi Merkuri Ion ke Merkuri Metalik

Article

Full-text available

Sep 2020

The presence of mercury in crude oil creates problems in oil processing in refineries, both in terms of operations and health. The previous removal process of mercury has not yet optimally removed mercury in the product, due to ionic and metallic mercury species. In this study, to obtain optimum results, the process of removal of mercury begins with the process of converting ionic (non-metallic) mercury into metallic mercury thermally in the liquid phase, followed by the transfer of metallic mercury to the gas phase by instant evaporation (flashing) and reinforced by gas stripping using internal gas cone from the evaporation of an instant. The results of the optimization of the process carried out can eliminate mercury with an efficiency of more than 95%.

The influence of sediment thermal maturity and hydrocarbon formation on Hg behaviour in the stratigraphic record

Preprint

Full-text available

Nov 2022

Spatial distribution of total mercury and methylmercury in the sediment of a tropical coastal environment subjected to heavy urban inputs

Article

Oct 2022
CHEMOSPHERE

Jurujuba Cove is located in Guanabara Bay (adjacent to highly populated city of Rio de Janeiro, Brazil), which receives diffuse sources of contaminants along with two main freshwater inputs (the Cachoeira and Icaraí rivers), and hosts mussel farms. The main goal of this work was to evaluate the total mercury (THg) and methylmercury (MeHg) concentrations distributions in the sediments of the cove and their associations with physical and chemical parameters, thereby assessing their geochemical behavior. Twenty samples of surface sediments were collected and characterized for grain size, pH, redox potential, organic carbon, total phosphorus, THg and MeHg. Spatial distribution maps were produced for each parameter and a principal components analysis was carried out, to assess THg and MeHg behavior and their relationships with other parameters. The principal components analysis showed that grain size functions as the main diluting agent. The highest THg concentrations were observed in the mussel-farm area (656.1 ng g⁻¹), and were related to fine grain size and elevated organic carbon values. High MeHg concentrations also occurred in the center of the cove, probably favored by high organic carbon content (low-energy environment). Total phosphorus concentrations indicate that Cachoeira River is a possible source of sewage, but little mercury seems to come from it. The results showed that although total mercury concentrations are elevated, with exception of a few locations, small methylmercury convertion rates were recorded in the sediments.

Ultra-trace Hg determination in crude oils by CV-ICP-MS: overcoming the limitations of sample preparation to determine sub-ppb levels

Article

Jan 2022

A method was developed to determine Hg in crude oil at sub-ppb levels by cold vapor generation inductively coupled plasma mass spectrometry (CV-ICP-MS) after wet digestion in a microwave-assisted system with a pressurized cavity.

Two decades of changing anthropogenic mercury emissions in Australia: inventory development, trends, and atmospheric implications

Article

Full-text available

May 2022

Mercury is a toxic environmental pollutant emitted into the atmosphere by both natural and anthropogenic sources. In Australia, previous estimates of anthropogenic mercury emissions differ by up to a factor of three, with existing inventories either outdated or inaccurate and several lacking Australia-specific input data. Here, we develop a twenty-year inventory of Australian anthropogenic mercury emissions spanning 2000-2019 with annual resolution. Our inventory uses Australia-specific data where possible and incorporates processes not included in other Australian inventories, such as delayed release effects from waste emissions. We show that Australian anthropogenic mercury emissions have decreased by more than a factor of two over the past twenty years, with the largest decrease from the gold production sector followed by brown coal-fired power plants and commercial product waste. Only the aluminium sector has shown a notable increase in mercury emissions. Using a global 3-D chemical transport model (GEOS-Chem), we show that the reduction in emissions has led to a small decrease in mercury deposition to the Australian continent, with annual oxidised mercury deposition ∼3-4% lower with present day emissions than with emissions from the year 2000. We also find that Australian emissions are not accurately represented in recent global emissions inventories and that differences between inventories have a larger impact than emissions trends on simulated mercury deposition. Overall, this work suggests a significant benefit to Australia from the Minamata Convention, with further reductions to Australian mercury deposition expected from decreases in both Australian and global anthropogenic emissions.

Novel Determination of Trace Metals in Geological Materials Employed in Food Products by Microwave Decomposition and Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES)

Article

Jan 2022

A new methodology for the determination of trace metals in geological materials employed in the food industry by single-reaction chamber (SRC) microwave digestion followed by inductively coupled plasma – optical emission spectrometry (ICP-OES) analysis was developed. The presence of toxic elements for human beings, such as As, Cd, Cr, Hg, Ni, and Pb, must be controlled in those materials that are in contact with food. Most regulations require the presence of these elements in these materials in low concentrations, mostly less than 1 mg kg⁻¹, which requires analytical methodologies that can reach these quantification limits. In the optimization of the sample preparation by microwave digestion, different mixtures of acids were used, so that As, Cd, and Hg were decomposed in an inverse aqua regia solution, while extraction of solid sample with aqua regia and HF was needed to determine Cr, Ni, and Pb. The determination of the analytes present in these solutions was carried out by ICP-OES, optimizing the conditions to obtain the best signal-to-noise ratio for each analyte. The study was undertaken using certified reference materials, two samples of clay, and a sample of sepiolite. Quantification limits of 1 mg kg⁻¹ were achieved, which meet the legal requirements. The analyzed samples of clays and sepiolite contained values of Cd and Hg that met the requirements although the results for As, Cr, Ni, and Pb were above the limits required for the food industry.

In-line measurement of exhaust mercury emissions by an instrumented light-duty vehicle using both on-road and test track experiments

Article

Sep 2021
SCI TOTAL ENVIRON

The initial purpose of this study has been to develop an instrumental platform for monitoring mercury (Hg) emissions from vehicle exhausts under actual traffic conditions. The platform was then mounted onto a fully-instrumented passenger car to identify emission proxies and factors governing the emissions of gaseous elemental Hg (GeM) and its complementary fraction (GdPM). Data obtained from the road were complemented by data acquired on a test track at either stabilized speeds or well-characterized speed variations. GeM emissions increased overall with both driving speed and fuel consumption; nonetheless, they were influenced by the sequence of accelerations and duration associated with the preceding idling or low-speed driving situations. GdPM emissions varied considerably over the course of trips or track tests, with medians ranging from 7% to 70% of the total Hg emissions stemming from fuel. Such high percentages could be explained by a series of redox reactions, whose kinetics and yield were influenced as much by exhaust gas temperature as by driving conditions or the exhaust system structural configuration. Lastly, an analysis of the GeM and GdPM signals showed that urban cores constitute emission hotspots during rush hour when handling low-speed driving and stop-and-go traffic.

Minireview on the Evolution of Tetrathiometallate Salts as Protean Building Blocks of Catalysts and Materials for the Energy Transition: Recent Advances and Future Perspectives

Article

Sep 2021

Michael A. Reynolds

Mercury Stable Isotopes as Tracers in the Environment: Applications to Aquatic and Natural Gas Systems

Thesis

Jan 2018

Spencer J Washburn

Mercury (Hg) is a neurotoxic trace metal pollutant with a global distribution and a complex biogeochemical cycle. Gaining a better understanding of the behavior of Hg in the environment has implications for both environmental and human health. Anthropogenic activity has directly altered the biogeochemical cycling of Hg, both by the direct release of Hg to the environment related to historic use (i.e. mining, industrial activity) as well as ongoing emissions of Hg as a byproduct of energy production (i.e. coal and natural gas combustion). There are still significant uncertainties in the understanding of how anthropogenic Hg sources, both legacy and modern, affect global Hg cycling and environmental health. The developing study of Hg stable isotope ratios in environmental samples has presented a new tool for understanding the processes that control Hg biogeochemistry. Throughout this dissertation, we have applied measurements of Hg stable isotope ratios in samples from sites affected by anthropogenic Hg contamination to enhance understanding of the biogeochemical behavior of Hg. In Chapter 2 and 3, we focused on understanding the Hg cycling within freshwater aquatic ecosystems by studying the South River, VA, which is the site of historic industrial Hg contamination. To describe the large range of observed Hg isotopic variation within the channel environment, a source end-member mixing model was proposed, identifying a regional background end-member and two end-members deriving from the historic industrial activities. We observed for the first time a discharge-dependent isotopic partitioning of Hg between the dissolved and suspended particulate phase of surface waters and proposed a fractionation mechanism to explain this observation. Examination of sediments of a floodplain profile provided evidence that there was significant temporal variability of the isotopic composition of past releases of Hg into the South River, with brief excursions in isotopic composition in the past recorded in the floodplain profile. In Chapter 4, we present the first measurements of the isotopic composition of Hg within natural gas. To obtain these measurements, we analyzed catalysts from mercury removal units at gas processing facilities that served to concentrate Hg for isotopic analysis. Significant variation in the isotopic composition of Hg within natural gas on a global scale was observed, as well as the regional scale. With further work these results could be used to investigate the impacts of natural gas processing at a local scale and could be included in Hg emissions models that incorporate Hg isotope mass balances. Altogether, this dissertation has expanded the use of stable Hg isotope ratios as tracers of anthropogenic Hg releases to the environment.

PRESENCE OF MERCURY IN PETROLEUM

Article

Dec 2006

The present article is a review of current knowledge of the presence of mercury in petroleum and natural gas. The effect of mercury on petrochemical processes and its removal are also discussed.

Levels of Mercury in oil companies and relation of them with the other elements for avoid side effect on the extraction and refining operation and environment

Article

Full-text available

Dec 2019

For the first time in Iraq, the estimation of the mercury amount in all the establishments of oil mininstry, is stuided in this wrok. It was found that the presence of mercury in the crude oil, theassociated gas, and the associated water as well as in most flare gases. Also, it was observed that the concentration of mercury on the surface of the soil near the flame is increased its concentration in winds of the flame, where most of the days of the year the wind is coming from the north West towards the south-east. The test of mercury has become a global provision to determine its quantity in crude oil and natural gas, which is required the effective ways, led by the Technical Department of the Ministry of Oil to request the petroleum research and development center to determine the amount of mercury in a number of oil companies. This work is proposed by the analytical department of the petroleum research and development center where the cold testing device was imported for the determination of the tiny amount of mercury in gases, liquids and soil and the detection limit in Nano grams. It is the first device operating in the oil sector using for the determination of mercury amount. However, the search results and quantification of mercury, important relationships were identified in terms of the presence of mercury and other crude oil components or tests on crude oil. It was found that there is a correlation between the concentration of mercury and the sulfur content in oil. Mercury is a volatile substance either vapor, dust, or sulfuric. Therefore, the oil gas contains a percentage of mercury, over time, formed by the burning of the gas and the pollution of air and the soil surrounding the flame, which constitutes an environmental hazard that must be avoided in the future. In addition, the accompanying water has a significant content of mercury.

Elevated concentrations of mercury and methylmercury in the Gadani shipbreaking area, Pakistan

Article

Full-text available

Apr 2021
MAR POLLUT BULL

Gadani shipbreaking area, Pakistan, is the world's third largest shipbreaking unit. However, to date, only a few studies on the environmental impacts of the industry, including mercury (Hg) pollution, have been conducted. To address this, concentrations of total Hg (HgT) and methylmercury (MeHg) were measured in surface sediments collected from the Gadani shipbreaking area as well as a local reference area. The highest concentrations of HgT and MeHg (median ± interquartile range) were detected in samples from the beach at the yard zone (HgT: 270 ± 230 μg kg⁻¹, MeHg: 0.65 ± 0.69 μg kg⁻¹), followed by sediment samples from the inter/sub-tidal zone where ships are dismantled (HgT: 20 ± 5.8 μg kg⁻¹, MeHg: 0.043 ± 0.016 μg kg⁻¹). These concentrations were on average 4–50 and 3–30 times greater than the concentrations of HgT and MeHg, respectively, observed in the reference area. Capsule Elevated concentrations of total and methylated mercury observed in the Gadani Shipbreaking area sediments.

Amphiphilic Thiol Polymer Nanogel Removes Environmentally Relevant Mercury Species from Both Produced Water and Hydrocarbons

Article

Jan 2021

Technologies for removal of mercury from produced water and hydrocarbon phases are desired by oil and gas production facilities, oil refineries, and petrochemical plants. Herein, we synthesize and demonstrate the efficacy of an amphiphilic, thiol-abundant (11.8 wt % S, as thiol) polymer nanogel that can remove environmentally relevant mercury species from both produced water and the liquid hydrocarbon. The nanogel disperses in both aqueous and hydrocarbon phases. It has a high sorption affinity for dissolved Hg(II) complexes and Hg-dissolved organic matter complexes found in produced water and elemental (Hg0) and soluble Hg-alkyl thiol species found in hydrocarbons. X-ray absorption spectroscopy analysis indicates that the sorbed mercury is transformed to a surface-bound Hg(SR)2 species in both water and hydrocarbon regardless of its initial speciation. The nanogel had high affinity to native mercury species present in real produced water (>99.5% removal) and in natural gas condensate (>85% removal) samples, removing majority of the mercury species using only a 50 mg L-1 applied dose. This thiolated amphiphilic polymeric nanogel has significant potential to remove environmentally relevant mercury species from both water and hydrocarbon at low applied doses, outperforming reported sorbents like sulfur-impregnated activated carbons because of the mass of accessible thiol groups in the nanogel.

Methods for Total and Speciation Analysis of Mercury in the Petroleum Industry

Article

Full-text available

Nov 2020

Fine and Coarse Particle-Bound Mercury in (Bio)fuels and Biodiesel/Diesel Exhaust under Real World Circumstances

Article

Aug 2020

In order to better understand the role of the Hg atmospheric samples, in this work we investigated how much Hg there is in a commercially available biodiesel/diesel mix (B7, 7 % v v-¹ biodiesel to petroleum diesel), in the Urban Dust reference material SRM1649b, in samples freshly and directly emitted by heavy-duty vehicles, and in ambient air. Total Hg in diesel B7 fuels from five different gas companies, ranged from 0.50 to 1.10 µg kg-¹, being 0.79 ± 0.05 µg kg-¹ (average ± one standard deviation). Following, in the SRM1649b analysis, we found Hg at 1.75 ± 0.01 mg kg-1, which is equivalent to more than 97.2 % recovery when compared to the certified value. In order to evaluate particulate Hg emissions under near real-life conditions, we collected PM2.5 and PM10 samples in an underground floor bus station. Total Hg levels for the bus station were 2.90 ± 1.15 µg g-¹ for PM2.5 and 2.19 ± 1.00 µg g-¹ for PM10. Particulate Hg in ambient samples were 1.82 ± 0.87 µg g-¹ (site 3, Itaparica, ITA) to 9.11 ± 4.17 µg g-¹ (site 1, Navy Base of Aratu, BNA) for PM2.5 and 1.31 ± 0.89 µg g-¹ (ITA) to 3.57 ± 1.25 µg g-¹ (BNA), for PM10. Either in bus station or ambient samples we found the PM2.5 mass is about 60 % of the PM10 mass, which explains particulate-bound Hg is mainly found in fine particles. Risk assessment through inhalation was done for adults, adolescents, children and infants. Although the highest DIE (daily inhalation exposure) values were observed for the bus station as well as the lowest DIE values were found to be from ITA, the risk levels are considered low.

Elemental Mercury Partitioning in High Pressure Fluids Part 2: Model Validations and Measurements in Multicomponent Systems.

Article

Aug 2020
FLUID PHASE EQUILIBR

A good understanding of the solubility of elemental mercury over wide ranges of temperature, pressure and composition is an important issue to assess the possibility of mercury dropping out in gas processing streams. In this work, new mercury solubility in three multicomponent systems with methane content varying between 89 – 26 mol% have been measured over a wide range of temperature (243.15 to 323.15 K) and pressure and up to 20 MPa. A group contribution method for the Peng-Robinson equation of state has been used to allow calculation of binary interactions between mercury and saturated hydrocarbons, aromatic hydrocarbons, nitrogen and carbon dioxide. The parameters of the group contribution have been adjusted using mercury solubility previously measured in single components. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.

Tackling elemental mercury removal from the wet-gas phase by enhancing the performance of redox-active copper-based adsorbents utilising an operando pre-heating system

Article

Full-text available

Aug 2020

Smart tuning of copper coordination using contaminant in dynamic natural gas feed to capture mercury – turning toxic to sustainable.

Synthesis of a new Thiophenol-Thiophene Polymer for the Removal of Mercury from Wastewater and Liquid Hydrocarbons

Article

Jul 2020

This work reports the synthesis of a novel thiophenol-thiophene polymer (termed KFUPM-Hg) and its suitability as an adsorbent for mercury removal from wastewater and liquid hydrocarbons. KFUPM-Hg was synthesized through a Friedel-Crafts polycondensation reaction of thiophenol and thiophene in the presence of p-formaldehyde as a linker. The crosslinked polymer structure was characterized using solid-state ¹³C- nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis was performed to assess the polymer thermal stability, which indicated that the polymer is thermally stable to over 300°C. A series of batch adsorption studies were used to investigate the effects of different parameters (pH, temperature, concentration, and time) on the mercury removal from aqueous solution as well as from a model liquid hydrocarbon media (decane/toluene mixture). The batch adsorption studies in aqueous media showed near quantitative removal of inorganic mercury (II) at 100 ppm using the thiophenol-thiophene polymer adsorbent. Furthermore, the thiophenol-thiophene polymer demonstrated excellent removal capabilities of methylmercury in a decane/toluene hydrocarbon mixture. Mercury adsorption onto KFUPM-Hg is an exothermic reversible physical process and follows pseudo-second order adsorption kinetics. Remarkably, these removal capabilities were achieved using polymers that directly incorporated thiophenol and thiophene groups during synthesis without the use of thiol-ene post-synthesis modifications.

Ionic mercury captured by H2S sulfurized biochar in liquid hydrocarbons: Mechanism and stability evaluation

Article

Oct 2020
FUEL

Three kinds of biochar, tobacco, rice and wheat, were treated with H2S to remove Hg(II) from hydrocarbons. The removal efficiency of the three biochars without H2S treatment was less than 12%. The removal efficiency of H2S treated tobacco had the best performance, and the removal efficiency increased by more than 87%. The characteristics of H2S treated biochar were analysed by FTIR, XPS, and TPD. The inorganic sulphides played a major role through ion exchange with metals. The sulphur-containing functional group C-S in organic sulphides and the carbonyl group C = O played a secondary role in the process of mercury removal through functional group complexation. In addition, the chemical and physical properties of gasoline before and after adsorption were compared to demonstrate that the sorbents had little effect on the heating value and the structure of hydrocarbons. The modified biochar also showed good stability after a life cycle test.

Experimental Tests of Natural Gas Samplers Prior to Mercury Concentration Analysis

Article

Dec 2019

Mercury (Hg) is a natural, trace component of natural gas. Corrosion of aluminum heat exchangers by liquid metallic Hg can lead to dramatic issues. The quantification of gaseous Hg concentration in natural gas streams is therefore crucial prior to the implementation of Hg removal units for preventing the formation of liquid Hg. Different methodologies exist for the determination of Hg concentration in natural gas, one of which relies on the sampling of natural gas at high pressure using stainless-steel cylinders prior to off-site Hg measurement. An inert internal coating is supposed to hamper Hg adsorption, presumably making the Hg analysis reliable. Here, we challenge this statement by showing that even silicon-coated cylinders are inefficient for preventing Hg adsorption on internal walls. Different cylinders were tested for gaseous Hg concentration stability over time in a clean Argon matrix. We find that gaseous Hg concentration sharply declines in almost all tested cylinders (uncoated, PTFE-coated and silicon-coated) to reach undetectable levels within a day or two due to adsorption, with the notable exception of a brand new silicon-coated cylinder. Heating cylinders up to 190 °C allowed the recovery of most of the adsorbed Hg and revealed the occurrence of two distinct Hg species with distinct release temperatures. Our results suggest Hg0 is first physically adsorbed and further oxidized, presumably in relation to sulfur compounds covering the internal walls of the cylinders. The newly purchased silicon-coated cylinder kept a constant gaseous Hg concentration over 6 months because it never interacted with any real Natural Gas sample containing substantial sulfur concentrations relative to Hg.

Regenerable α-MnO2 nanotubes for elemental mercury removal from natural gas

Article

Oct 2019
FUEL PROCESS TECHNOL

The elemental mercury (Hg⁰) vapor removal ability of α-MnO2 nanotubes (NTs), nanorods (NRs) and nanowires (NWs) was evaluated in simulated natural gas mixtures. It was shown that NTs exhibited superior efficiency (~100%) at the temperature range of interest (25–100 °C). The Hg⁰ breakthrough (corresponding to 99.5% Hg⁰ removal efficiency) at ambient conditions and Hg⁰in = 870 μg∙m⁻³, occurred after 48 h, reflecting a Hg⁰ uptake of >10 mg∙g⁻¹ (1 wt%). Most importantly, the developed nanosorbent was repeatedly, sufficiently regenerated at the relatively low temperature of 250 °C in a series of seven successive sorption-desorption tests, maintaining its capacity to remove all incoming Hg⁰in in each cycle. Interestingly, kinetic studies showed that at least 85% of total adhered Hg⁰ could be recovered within the first hour of a 3-h regeneration process. Moreover, the presence of CO2 and H2S did not affect its activity. The thermogravimetric analysis indicated significantly higher dehydration for NTs due to the loss of bound water inside its tunnels, likely indicating the presence of abundant surface adsorbed oxygen species which are believed to facilitate Hg⁰ adsorption. This was also confirmed by X-ray spectroscopy, possibly explaining the enhanced activity of NTs.

The mercury isotope signatures of coalbed gas and oil-type gas: Implications for the origins of the gases

Article

Aug 2019
APPL GEOCHEM

The concentration of mercury vapor (elemental mercury, Hg⁰) in natural gases has been used to differentiate between coalbed gas and oil-type gas. However, the concentrations of Hg⁰ in coalbed gas and oil-type gas are highly variable, and its use as a genetic indicator is problematic. Here, for the first time, we report significant differences in the mass-dependent fractionation (MDF, measured with δ²⁰²Hg) and the mass-independent fractionation (MIF, measured with Δ¹⁹⁹Hg, Δ²⁰⁰Hg and Δ²⁰¹Hg) of Hg⁰ isotopes between coalbed gas and oil-type gas. Coalbed gas has an extremely negative δ²⁰²Hg (−5.8‰ to −3.08‰) and negative Δ¹⁹⁹Hg (−0.19‰ to −0.01‰) relative to the assumed source, which is Permian coal from the Henan Province, China. Oil-type gas is characterized by less negative δ²⁰²Hg (−3.08‰ to −0.77‰) and positive Δ¹⁹⁹Hg (0.06‰–0.30‰) relative to its E2-3s source rocks in the Liaohe oilfield (dark mudstones: δ²⁰²Hg = −1.96‰ to −2.48‰, Δ¹⁹⁹Hg = 0.09‰–0.17‰). This significant difference in the MIF can be used to distinguish between coalbed gas and oil-type gas. Notably, the Δ²⁰⁰Hg values of our samples are as high as 0.15‰. We suggest that significant Hg⁰ MDF might occur during the formation of coalbed gas, but not during the formation of oil-type gas. This study highlights the potential of Hg⁰ isotopes as proxies for the source of natural gases.

Analysis of Metals in Condensates and Naphtha by Inductively Coupled Plasma Mass Spectrometry

Article

Full-text available

Nov 1997
ANALYST

Condensates and naphtha are petroleum samples with largely gasoline-range components (C5–C10). Metal organic complexes are source inherited components of oils which are associated with the polar components and asphaltenes of oils. Because of the very low levels of biomarkers such as hopanes and steranes in condensates, they present a special correlation problem. Geochemically significant metals, such as V and Ni, can be measured in some condensates using conventional Meinhardt–Scott chamber inductively coupled plasma mass spectrometry (ICP-MS). In order to increase the sensitivity and the range of condensates which can be analysed, the Cetac U-6000 AT Ultrasonic nebuliser–desolvation system was tested. The Cetac system improved the sensitivity for V and Ni by a factor of about 40. Valuable information for relating these difficult samples to each other and to heavier oils in a basin can thus be supplied to exploration geochemists. The influence of organic matrix on the analytical signal was investigated. Matrix effects are more pronounced for the Cetac system than for the conventional ICP-MS system. For both systems, the use of an In internal standard was found to be necessary for compensating for differences in nebulisation and combustion behaviour caused by variations in the nature of the sample. The use of ICP-MS for the analysis of toxic metals such as Hg and Pb in condensates and naphthas is also discussed. The results are compared with those obtained using electrothermal atomic absorption spectrometry and cold vapour atomic absorption spectrometry in an interlaboratory study of naphthas. Conventional Meinhardt–Scott chamber ICP-MS provided good accuracy and precision of analysis compared with the other techniques during this study. Volatile species such as Et4Pb and Me2Hg were lost in the desolvation unit when using the Cetac system. Volatilisation effects were not observed when using the conventional Meinhardt–Scott chamber ICP-MS system.

Determination of Elemental, Inorganic and Organic Mercury in North German Gas Condensates and Formation Brines

Article

Full-text available

Feb 1997

Mercury is present in many north German gas reservoirs producing from Permian sandstone (Rotliegend formation). When the pressure and temperature of the produced gas are reduced in surface facilities, most of the accompanying mercury (700 to 4400 g/m3) is precipitated in separators. Still, a certain amount of mercury might remain in the hydrocarbon condensate and the produced brine. Total mercury concentrations in condensate and brine were determined with a view to safety of field workers and restrictions imposed by refineries processing the condensates. Furthermore, the individual concentrations of the highly toxic organic mercury compounds, of inorganic mercury compounds, and elemental mercury were analyzed, applying a new process for R-Hg-X compounds. In the process, mercury species are complexed with specially selected ligands and separated on an HPLC column. The complexes are destroyed by post-column oxidation with UV irradiation and analyzed by means of cold vapor atomic absorption spectrometry. Low detection limits were achieved by on-line preconcentration. While the total mercury content in brine was less than 1 mg/l, total mercury in condensates amounted to 3 to 6 mg/l. Dialkyl-diphenyl mercury compounds were not detected. Out of the group of monoalkyl mercury compounds, only methyl mercury was detected in concentrations of between 0.005 and 0.1 mg/l, the same proportion as found e.g. in sea fish. Introduction Mercury exists naturally in many gas reservoirs worldwide, for example in the United States, Canada, China, Japan, The Netherlands, and Germany. Gas produced from the Rotliegend sandstone in North Germany exhibits especially high amounts of mercury in raw gas. The "mercury source" is the underlying Volcanite, which - as its name says - is of volcanic origin. In gas recovery operations, mercury is mainly found in elemental form, but some authors reported the occurence of mercury compounds and alloys as well. Inorganic and organic Hg compounds have been identified, and the extremely toxic nature of organic mercury compounds makes even low concentrations dangerous to health, safety, and environment. Among the organic mercury compounds, monoalkyl- (or monoaryl-)mercury [R-Hg-X, X=halide, sulfate, or -S-R], and dialkyl mercury compounds are distinguished. The dialkyls, especially dimethy/mercury, are even more toxic than the monoalkyls and caused fatal poisonings at the time of their discovery. The Threshold Limit Value of organic mercury compounds in Germany is 0.01 mg/m3. Dialkyl mercurials are fairly volatile (boiling point of (CH3)2Hg: 96 C) and soluble in organic solvents, while monoalkyl mercurials with sulfate counterions as well as inorganic mercury compounds are water soluble. On the other hand, monoalkyl mercurials with chloride or alkyl sulfide (-SR) counterions prefer organic solvents. Thus, organic mercury compounds might be found in the organic phase (gas condensate) and in the aqueous phase (formation brine). Besides the toxicity of mercury and its compounds, mercury can lead to severe corrosion problems in gas treatment plants and to catalyst poisoning in refineries processing gas condensates. P. 509^

Design mercury removal systems for liquid hydrocarbons

Article

Apr 1999
HYDROCARB PROCESS

S.M. Wilhelm

Mercury removal systems (MRSs) for hydrocarbon liquids in primary gas processing facilities are used to reduce the concentration of mercury and mercury compounds in liquid products to low levels. The conceptual design of such systems must take into account a variety of technical and economic considerations. The key elements to be considered in the conceptual design are location in the process, removal system selection and cost. Acquisition of data and information to allow decisions in these categories is the main objective. Computer programs and models are useful to assist cost comparisons of candidate scenarios.

Mercury in the environment: biogeochemistry

Article

Jan 1994

D.B. Porcella

Mercury speciation in natural gas condensate by gas chromatography-inductively coupled plasma mass spectrometry

Article

Oct 1998
J ANAL ATOM SPECTROM

A simple and rapid GC-ICP-MS speciation method for mercury in natural gas condensate is described. The use of a polar DB-1701 column, pre-treated with HBr, permitted sharp peaks for monoalkylmercury species and also other species without derivatization. Six organomercury species, DMeHg, MeEtHg, DEtHg, MeHgCl, DBuHg and EtHgCl (D=di-), were baseline separated from Hg0 and HgCl2 within 6 min when the pulsed splitless injection mode was used. Separation of Hg0 from HgCl2 was performed using the on-column injection mode. The detection limits were 150 fg for Hg0, 340 fg for HgCl2, 200 fg for DMeHg, 19 fg for MeEtHg, 35 fg for DEtHg, 74 fg for MeHgCl, 50 fg for DBuHg and 36 fg for EtHgCl as Hg for the pulsed splitless injection mode. The detection limits for Hg0 and DMeHg were improved to 34 and 130 fg, respectively, with the on-column injection mode. The relative standard deviations of seven replicates of a mixed standard containing approximately 30 µg l–1 Hg of each species ranged from 1.6 to 3.8% and from 1.6 to 2.7% with the pulsed splitless and on-column injection modes, respectively. Recoveries for DEtHg, MeHgCl and EtHgCl from natural gas condensates ranged between 90 and 103%, but those for Hg0, HgCl2 and DMeHg deviated considerably from 100% owing to overloading by coexisting hydrocarbons. Transalkylation during GC separation did not take place with either injection mode, but decomposition was observed with the pulsed splitless injection mode. The method was applied to natural gas condensates, naphtha fractions and a crude oil sample. Five species, Hg0, HgCl2, DMeHg, MeEtHg and DEtHg, were identified in the real samples, ranging from the sub-ppb to several tens of ppb levels. The existence of MeEtHg in natural gas condensates was identified for the first time.

Process for removal of mercury vapor and adsorbent therefor

Article

Jan 1985

Mercury vapor in a gas can easily be removed from the gas by contacting the gas with an adsorbent comprising an activated carbon having as supported thereon components selected from sulfur, sulfate and nitrate of Al, V, Fe, Co, Ni, Cu, Zn, or NHâ, and oxide of iodine, oxyacid corresponding to the oxide of iodine, salt of said oxyacid, and bromide and iodide of K. Na or NHâ

Thailand's Initiatives on Mercury

Article

Apr 1997

Nutavoot Pongsiri

Mercury has been known to be a trace contaminant in natural gas and condensate produced from Unocal Thailand's operations in the Gulf of Thailand since 1985. It has been detected in well streams, produced formation water, and also in solid waste. Mercury is recovered from process vessels, wellhead chokes, piping, and storage tanks. Almost all of the mercury found in natural gas and produced formation water is in elemental form, but in condensate, mercury is mostly in the colloidal form. Unocal Thailand has taken various proactive steps to minimize and limit both people's exposure to mercury and any impact on the environment, in full compliance with applicable laws and regulations. An example of environmentally sound treatment to dispose of mercury-contaminated solid waste is the deep-well injection technique. Another successful in-house developed technology, currently applied to the treatment of discharge water containing trace mercury, is a system using both gravitational separation and chemical flocculation techniques. Introduction Unocal Thailand, a subsidiary of Unocal Corporation, is currently producing offshore natural gas and condensate from nine fields in the Gulf of Thailand. Unocal Thailand's offshore facilities include four central processing platforms, four production platforms, and sixty well platforms. During the first six months of 1996, Unocal Thailand produced a dally average of 757 million cubic feet of natural gas and 27,090 barrels of condensate. Following gas and condensate processing, production platforms and central processing platforms discharge produced formation water into the sea at a daily average of 23,800 barrels/day. Liquid hydrocarbons in the subsurface reservoirs in the Gulf of Thailand contain trace mercury in organic complex form. Due to high temperature in the reservoirs, this mercury is thermally decomposed to elemental form. Unocal Thailand has detected mercury in gas, condensate, and produced formation water. However, most of the mercury has been recovered from the process with the solid sludge. Mercury in the Gulf of Thailand The Gulf of Thailand is approximately 720 km. in length, with a coastline of 2,900 km. and a maximum depth of 84 m. The central portion of the Gulf is over 60 m. deep and is separated from the South China Sea by two ridges at depths of 25 and 50 m., respectively. Unocal Thailand's facilities are located near the center of the Gulf; approximately 100 km. from the coast. Sources of mercury which migrates in aquatic environments as illustrated in Figure 1 can be man-made discharges through industrial and domestic wastes and natural discharges through leaching and volatilization of the geological formations containing significant quantities of mercury such as the volcanic fumaroles. There is some evidence indicating natural mercury leaching in the Gulf. The data collected from 12 plugs from conventional cores in Unocal's new exploration area, Pailin field, indicated high mercury content, ranging from 0.02 ppm to 0.23 ppm, associated with coal stringers. Other sources and pathways responsible for mercury contamination in sea water in the Gulf also include atmospheric fallout and direct discharge of industrial and domestic wastes into the five major rivers (the Chao Phraya, the Mae Klong, the Ta Chin, the Bang Pakong, and the Tapi) which flow into the Gulf. These rivers pass through the industrial areas that contribute a significant amount of heavy metals to the river estuary. The estimated amount of mercury which enters the Gulf from atmospheric deposition is 5,000 kg/yr., and estimates from terrestrial runoff range from 5,000 to 10,000 kg/yr. There are various forms of mercury found in river runoff such as inorganic divalent-mercury, metallic-mercury, phenyl-mercury, methyl-mercury, and alkoxyalkyl-mercury. P. 553

Purification of fluid streams containing mercury

Article

Jan 1991
Zeolites

J MARKOVS

Mercury is selectively removed to very low levels of concentration from fluid streams such as natural gas, cracked gas, hydrogen or naphtha by passage of the stream through an adsorbent bed containing particles of a zeolitic molecular sieve having pore diameters of at least 3.0 Angstroms and in which the zeolite crystallites forming the outer shell of the adsorbent particle to a depth of not greater than about 0.1 millimeter into the adsorbent particle, contain ionic or elemental silver. These adsorbent particles are utilized to particular advantage in a compound adsorbent bed containing a desiccant substantially free of silver through which a fluid stream containing both mercury vapor and water vapor is both dried and purified with respect to mercury by passage therethrough, coupled with periodic regeneration of both media using conventional purge desorption methods.

A novel analytical method for determination of picogram levels of total mercury in gasoline and other petroleum based products

Article

Aug 1996
SCI TOTAL ENVIRON

A new and simple sample preparation method has been developed for the determination of mercury in gasoline and other petroleum products. The organo-mercury compounds in the materials are oxidized, while being extracted into the aqueous phase using an oxidant/acid solution, . The inorganic mercury is simultaneously extracted into the solution. The mercury extracted into the aqueous phase is then reduced to Hg0 by SnCl2 and detected by cold vapour atomic fluorescence spectrometer (CVAFS). The detection limit (DL), expressed as 3 S.D. of repeated measurements for the determination of a low concentration sample, was ∼0.01 ng/g. The method is sensitive enough to determine low levels of mercury in all gasoline samples studied with RSDs < 10%. The recoveries for determination of mercury in a certified reference material, Conoco, Jet Fuel CRM DRM 1080 were close to 100% with an RSD of ≤5%. Gasoline samples and other petroleum based materials, such as Kerosene, diesel and heating oil from different origins were analyzed and satisfactory results were obtained. The analytical results are independent of the mercury species studied making the use of direct standardization possible, thus ensuring the accuracy and reliability of the method. The concentrations found in most gasoline and other products were at or below 1 ng/g.

Highlight. Determination and speciation of mercury in natural gases and gas condensates

Article

May 1996
Anal Comm

The latest analytical techniques for species specific Hg determination in natural gases and condensates are reviewed along with total Hg concentration determination. The difficulties encountered by these techniques are highlighted.

Determination of the Recovery of Dimethylmercury and Diphenylmercury Extracted From Organic Solvents and a Liquid Condensate With Bromine Water Using Cold Vapour Atomic Absorption Spectrometry

Article

Oct 1997
Anal Comm

Cold vapour atomic absorption spectrometry was used to determine if bromine water extracts organic bound mercury quantitatively from liquid hydrocarbons. The method described is used for mercury determination by the oil industry but has not been previously published. It presents an extension to the existing standard ISO 6978: 1992 which deals with the determination of mercury in natural gases. The bromine oxidises the mercury to mercury(II)-ions. Then excess bromine is reduced by hydroxylammonium chloride to bromide. Finally the mercury(II)-ions are reduced by tin(II)-chloride to elemental mercury. The absorbance at 253.7 nm is measured spectrometrically and depends linearly on the mercury concentration. Quantitative tests of this method have been carried out previously on organic mercury compounds dissolved in water and living tissues. Test results on the validity of this method for organic mercury compounds dissolved in crude oils or condensates are presented in this communication. The recoveries of dimethylmercury and diphenylmercury dissolved in an organic solvent and in a liquid condensate–solvent mixture have been determined. For dimethylmercury it was found to be 98 ± 5% in heptane and 98 ± 6% in a condensate–heptane mixture. For diphenylmercury the recovery was found to be 93 ± 5% in a heptane–toluene mixture and 95 ± 5% in a heptane–toluene–condensate mixture.

On the determination of total mercury in natural gases using the amalgamation technique and cold vapour atomic absorption spectrometry

Article

Oct 1995
J ANAL ATOM SPECTROM

Studies on the use of noble metal collectors for the amalgamation of mercury from natural gas prior to thermal desorption and determination by cold vapour atomic absorption spectrometry have been performed. It is shown that collectors filled with gold/platinum wire are more efficient than those packed with gold or silver wire. Quantitative sampling efficiencies are obtained for Hg0 and (CH3)2Hg added to natural gas when the gold/platinum collector is heated to 80 °C, at sampling rates < 2 l min–1 and for volumes of at least 10 l. The precision for field measurements was established to be between 8 and 15% relative standard deviation, and the detection limit for the developed procedure is calculated to be 30 ng m–3 for a 10 l sample (3s criterion).

Determination of total mercury in hydrocarbons and natural gas condensate by atomic fluorescence spectrometry

Article

Feb 1999
ANALYST

A new and simple technique for the determination of total mercury in gas condensate was developed which eliminates the use of chemicals/additives and complicated digestion procedures. The determinations are carried out by vaporisation of the samples at 400 °C with adsorption of mercury species on a gold trap (Amasil) maintained at 200 °C. The trap is then heated at 900 °C to release metallic mercury, which is determined by atomic fluorescence spectrometry. The mercury recoveries from seven species, dimethylmercury (DMM), diethylmercury (DEM), diphenylmercury (DPM), methylmercury chloride (MMC), ethylmercury chloride (EMC), phenylmercury chloride (PMC) and mercury(II) chloride (MC) spiked individually into gas condensate were found to be in the range 80–100%. The mercury recoveries for mixtures of the seven species added in equal amounts to gas condensate were in the range 88–97%. For Conostan mercury standard added to the condensate, the recovery was 88%. The instrumental precision from 10 measurements of a toluene control was 4% RSD. For three mercury species. DEM, MC and EMC, added to condensate, the precision was between 2 and 5% RSD (n = 10). The limit of detection (3ςn–1 criterion) for the procedure was calculated to be 180 pg Hg in toluene and 270 pg in condensate. For three mercury species added to a condensate sample, the absolute detection limits were 270 pg Hg for DEM, 450 pg Hg for MC and 630 pg Hg for EMC. Total mercury measurements in five real condensate samples from two sites at different stages of production covered the range 7–50 ng ml–1 with uncertainties in the range 4–7% RSD. The total mercury concentration of two commercial heavy gas oil samples were found to be 22.2 ± 0.6 µg ml–1 with RSD 3% (n = 4) and 2.3 ± 0.1 µg ml–1 of mercury with RSD 3% (n = 7).

Performance improvements in the determination of mercury species in natural gas condensate using an on-line amalgamation trap or solid-phase micro-extraction with capillary gas chromatography?microwave-induced plasma atomic emission spectrometry

Article

Aug 1996
ANALYST

An on-line amalgamation trap was constructed for the collection of mercury species separated by capillary GC for detection by microwave-induced plasma atomic emission spectrometry. For direct measurement of the column eluate, the detection limits for mercury species in natural gas condensate are elevated because of background interference from carbon compounds passed to the plasma at the same time. Carbon compounds give rise to emission that spectrally interferes with the signal from the mercury detector and can overload the plasma discharge, reducing the excitation capability. With an amalgamation trap, mercury can be selectively collected from the column eluate and subsequently passed to the plasma in a flow of pure helium. By removing the carbon background emission, the trap allows the determination of dimethylmercury in condensate down to a detection limit of 0.24 µg l–1 and derivatized (butylated) monomethyl and inorganic mercury down to a detection limit of 0.56 µg l–1 in natural gas condensate. Use of the trap is compared with some existing determination methods for mercury species in condensate and other samples. Solid-phase micro-extraction is used for dimethylmercury, which gives a poorer detection limit of around 20 µg l–1 because the analyte mass collected is small compared with liquid sample injection. Following derivatization, samples are diluted for direct methylbutylmercury and dibutylmercury determination, corresponding to methylmercury and inorganic mercury. Dilution ensures a reasonably stable background for mercury signals. Again, poorer detection limits of 3.1 and 2.3 µg l–1, respectively, are obtained owing to the reduced analyte mass. The trap permits the injection of untreated condensate, or condensate reacted with butylmagnesium chloride, into the gas chromatograph without the need for dilution or sample clean-up.

Stability and reactions of mercury species in organic solution†

Article

May 1998

The stability over time of elemental mercury, methylmercury and inorganic mercury species was evaluated in heptane, toluene and mixed hydrocarbon solutions, Elemental mercury and inorganic mercury(II) were determined using a specific extraction method followed by ICP-MS or CVAAS, Methylmercury and mercury(II) were determined by GC-MTP-AES after derivatisation with Grignard reagent, The results show that significant losses of mercury species from solution can occur by two pathways: by adsorption on the container wall and by reactions forming mercury(I) compounds. For the latter pathway, rapid losses of dissolved elemental mercury and mercury(II) chloride species occur when both are present in solution. For heptane solutions containing HgCl2, 80% of the HgCl2 remains after 13 d in a pure standard compared with 11% in a standard containing Hg-0. Mercury(I) compounds form a colloidal material, which is not soluble in these organic solvents at a detectable concentration, Mercury(I) compounds were butylated with Grignard reagent to form the organic mercury(I) compound (C4H9)(2)Hg-2 that was measured specifically by GC-MIP-AES and GC-MS. This new compound was stable and appeared to precipitate from solution.

A Practical Model for the Effect of Salinity on Gas Hydrate Formation

Article

Apr 1996

This paper is based on a previously developed thermodynamic model for gas hydrates and hydrate inhibition. The model uses a cubic equation of state for the fluid phases and parameters have already been determined for the following inhibitors methanol, MEG, DEG and TEG. The paper describes the extension of the model to include the effect of salinity in produced water or sea water on hydrate formation. To ensure the model would be of practical value, it was designed with the following characteristics: it should be simple to use requiring as input no more than a typical ion analysis table from a laboratory report. It should be based on a cubic equation of state suitable for engineering calculations and the model should operate reliably at temperatures and pressures normally encountered in oil and gas production. The model represents the ionic components in water by a single salt pseudocomponent of the equation of state. The physical properties of the pseudocomponent were set by regressing them to experimental data for sodium chloride solutions. Results will be presented to show that the model can simultaneously represent the lowering of the hydrate dissociation temperatures, the depression of the freezing point of water and the reduction in the water vapour pressure (osmotic coefficient). As sodium chloride is usually the dominant component in produced water or sea water, other salts are handled on a sodium chloride equivalent basis, so that only one salt pseudocomponent is needed for practical calculations. Data for the effect of natural water supports the use of this approximation. In practice, a hydrate inhibitor may be added to the water phase so it is important that the inhibition model can give accurate predictions in the presence of saline solutions. This has been confirmed by investigating the salting-out effect for methanol and results are shown for salt-water-methanol mixtures. Practical ways of accessing and applying the model are summarized. These include using the model as a standalone computer program, accessing the model via a spreadsheet or using the model as an object code library or as a dynamic link library. Introduction Gas hydrates are a well appreciated hazard in oil and gas pipelines and processing equipment. They may also occur in certain conditions during drilling operations giving rise to gas kick. If operating conditions are such that hydrates may form, hydrate inhibitors such as methanol or glycols have to be injected into the hydrocarbon fluid. If produced water or sea water is in contact with the hydrocarbon fluid, the salinity of the water will itself inhibit hydrate formation. The object of this work is to devise a practical engineering method to predict the effect of salinity on hydrate formation in combination with added chemical inhibitors. Existing Hydrate Model The authors have previously developed an original computer algorithm for solving multiphase equilibrium problems involving any number and combination of solid, liquid or gas phases1. The phases may have quite different properties calculated from different thermodynamic models. The altorighm can perform all the normal engineering flash calculations; it automatically determines which phases will be present under given conditions and returns the relative amounts, compositions and properties of the phases. To model the fluid phases, a commonly used equation of state was required. The choice was between the SRK2 or Peng-Robinson3 equations. The SRK equation was selected as it appears to give more accurate fugacities for natural gases4. The tendency of the SRK equation to give poor liquid densities was addressed by correcting the SRK densities using the Peneloux volume shift method5. Existing Hydrate Model. The authors have previously developed an original computer algorithm for solving multiphase equilibrium problems involving any number and combination of solid, liquid or gas phases1. The phases may have quite different properties calculated from different thermodynamic models. The altorighm can perform all the normal engineering flash calculations; it automatically determines which phases will be present under given conditions and returns the relative amounts, compositions and properties of the phases. To model the fluid phases, a commonly used equation of state was required. The choice was between the SRK2 or Peng-Robinson3 equations. The SRK equation was selected as it appears to give more accurate fugacities for natural gases4. The tendency of the SRK equation to give poor liquid densities was addressed by correcting the SRK densities using the Peneloux volume shift method5.

Mercury adsorbent carbon molecular sieves and process for removing mercury vapor from gas streams

Patent

Nov 1987

This patent describes a carbon molecular sieve for removing mercury vapor form gas streams, having a nitrogen diffusivity of less than 2600 x 10/sup -8/ cm/sup 2//second, impregnated with from about 0.005 to about 15%, by weight, of a mercury reactive material, wherein the carbon molecular sieve is effective at mercury vapor concentrations less than 4 x 10/sup -6/ x P/sub s/, where P/sub s/ is the mercury vapor saturation pressure at a given pressure and temperature. A process is described for removing mercury vapor from gas streams which comprises passing a gas stream containing mercury vapor into contact with a carbon molecular sieve, having a nitrogen diffusivity of less than 2600 x 10/sup -8/cm/sup 2//second, impregnated with from about 0.005 to about 15 percent, by weight, of a mercury reactive material, wherein the carbon molecular sieve is effective at mercury vapor concentrations less than 4 x 10/sup -6/ x P/sub s/ where P/sub s/ is the mercury vapor saturation pressure at a given pressure and temperature.

Processes prevent detrimental effects from As and Hg in feedstocks

Article

Jan 1993

The wide range of mercury and arsenic species sometimes present in raw condensates or crude oils can cause major problems such as corrosion and reduced catalyst life. This paper reports on simple, low-investment, feedstock treatment procedures which have been developed that eliminate both As and Hg impurities with very high efficiencies. During the past 20 years, refiners and petrochemical producers have experienced a serious increase in catalyst poisoning caused by mercury and arsenic. This phenomenon may be partically explained by the diversification of the feedstock supply resulting from the need to optimize the profitability of refining and petrochemical operations. The utilization of a more diverse feedstock supply containing metal impurities has led to operating problems such as corrosion of aluminum alloys in steam cracker cold boxes.

Determination of mercury species in gas condensates by on‐line coupled high‐performance liquid chromatography and cold‐vapor atomic absorption spectrometry

Article

Feb 1995
APPL ORGANOMET CHEM

A method for the speciation of mercury in gas condensates is reported. Mercury(II) chloride (HgCl2), methylmercury chloride (MeHgCl), phenylmercury acetate (PhHgAc) and diphenylmercury (Ph2Hg) are separated by reversed-phase high-performance liquid chromatography (HPLC) using gradient elution. Prior to the determination, the organic ligands and the matrix were destroyed by oxidation with K2Cr2O7. Mercury is detected with cold-vapor atomic absorption spectrometry (CVAA), where the mercury compounds are reduced to metallic mercury by a treatment with NaBH4. In a continuous-flow system the concentrations of the reagents used are optimized using a modified simplex algorithm. Detection limits for mercury are at the 10 ng ml−1 level. Analysis of multi-compound mixtures indicates that chemical reactions between HgCl2 and Ph2Hg and between MeHgCl and Ph2Hg take place. The method developed was applied to the speciation of mercury in gas condensates and did not require use of any solvent extraction or chemical derivatization steps. In the gas condensates, mercury(II) compounds were found to be present at the 100 ng ml−1 level.

Generation and Disposal of Petroleum Processing Waste That Contains Mercury

Article

Jun 1999
ENVIRON PROG

S. Mark Wilhelm

The origins and fate of mercury found in hydrocarbons are discussed from the perspective of waste minimization, treatment and disposal. Mercury is a common and naturally occurring component of petroleum. Petroleum processing often is accompanied by generation of waste streams that contain some mercury. These waste streams become problematic when the mercury concentration in process feeds exceeds a few ppb because of the highly toxic nature of mercury. Waste is minimized by mercury removal systems that are now prevalent for many processes, but the main incentive to employ such systems is to protect equipment and catalysts. The removal systems have varied waste disposal consequences depending on their chemical properties and process location. Absent mercury removal systems, mercury contamination results in sludge, sediments, contaminated treatment fluids and a variety of other waste streams that must be carefully controlled, segregated and treated for disposal. Waste containing mercury is characterized by chemical analysis that is capable of speciating the various forms of mercury and mercury compounds so as to be able to select treatment and disposal options. In many locations where the mercury concentration in process feeds is high, treatment systems for mercury are not readily available resulting in storage of toxic material for long periods of time. Both chemical and thermal treatment systems are commercially available, but access to cost effective treatment is extremely limited in the petroleum industry.

Neutron activation analysis of major and trace elements in crude petroleum

Article

Jan 1995

We have determined the concentration of 25 trace elements in crude petroleum from seven Libyan oil fields by instrumental neutron activation analysis. Crude oil samples were irradiated with a thermal neutron dose rate of 1012 and 1013 ncm–2s–1 in the Tajoura research reactor. The concentration of U, Br, Mg, Cu, Na, V, Cl, Al, Mn and Ca is in a range of 0.015 to 84 ppm and that of sulphur of 0.12 to 1.8%. The elements Sc, Cr, Ni, Fe, Co, Zn, Ag, Se, Sb, Ba, Cs, Yb, Hf and Hg have a concentration range of 0.009 to 8747 ppb. The coefficients of variation are within 10%. The elements V and Ni occur as both porphyrin and non-porphyrin and the ratio of these two forms varies over a wide range. The V/Ni ratios are located between 0.17 and 6.67, which are comparable to the reported values for the crude oils from other countries.

Performance comparison between furnace atomisation plasma emission spectrometry and microwave induced plasma-atomic emission spectrometry for the determination of mercury species in gas chromatography effluents

Article

Dec 1998
J ANAL ATOM SPECTROM

Samples (1 ml) of gas condensates were derivatized with 0.4 ml of 2M-butyl magnesium chloride in THF in an ice bath using 0.4 ml 0.6M-HCl to quench the reaction after 5 min. After centrifugation for 3 min at 540 rpm, 0.5-2.5 ml of the organic phase was injected into the gas chromatograph fitted with a DB-1 column with a ramped oven temperature between 50-180°C with He as carrier gas (8 ml/min). Emission was measured at 253.6 nm. Comparable detection limits were obtained from both sources for dimethyl-, methylbutyl- and dibutylmercury ranging from 0.5-4.1 pg, with detection limits in 5% diluted condensate of 1.5-4.7 pg. Measurement of dimethylmercury was not possible with MIP AES. A linear range of three decades was obtained for both sources. Molecular emission from NO caused background interference from both sources but these were reduced by hydrocarbon effluents in the furnace atomization plasma emission spectrometry source whereas with MIP background fluctuations arose mainly from plasma quenching.

Evolution of Our Understanding of Methylmercury as a Health Threat

Article

May 1996

Methylmercury (MeHg) is recognized as one of the most hazardous environmental pollutants, primarily due to endemic disasters that have occurred repeatedly. A review of the earlier literature on the Minamata outbreak shows how large-scale poisoning occurred and why it could not be prevented. With the repeated occurrences of MeHg poisoning, it gradually became clear that the fetus is much more susceptible to the toxicity of this compound than the adult. Thus, recent epidemiologic studies in several fish-eating populations have focused on the effects of in utero exposure to MeHg. Also, there have been many studies on neurobehavioral effects of in utero exposure to methylmercury in rodents and nonhuman primates. The results of these studies revealed that the effects encompass a wide range of behavioral categories without clear identification of the functional categories distinctively susceptible to MeHg. The overall neurotoxicity of MeHg in humans, nonhuman primates, and rodents appears to have similarities. However, several gaps exist between the human and animal studies. By using the large body of neurotoxicologic data obtained in human populations and filling in such gaps, we can use MeHg as a model agent for developing a specific battery of tests of animal behavior to predict human risks resulting from in utero exposure to other chemicals with unknown neurotoxicity. Approaches developing such a battery are also discussed.

Analysis and stability of mercury speciation in petroleum hydrocarbons

Article

Apr 2000

N. S. Bloom

Raw petroleum and natural gas often contain high concentrations of mercury, which can be damaging to the metal components of production facilities, as well as to the environment. Various Hg species have different properties in terms of mobility, reactivity and bioavailability. Thus, for cost-effective decisions regarding plant design, Hg extraction, and pollution control, speciation information must be available at the production facility. In this paper, a simple, wet chemical speciation method, which provides data on Hg(o), dissolved and particulate total Hg, Hg(II), and methyl Hg is presented. The method incorporates species-specific extraction and separation procedures, followed by cold vapor atomic fluorescence spectrometry (CVAFS). For each species, detection limits of approximately 0.1 ng/g were obtained. Storage experiments in various containers showed that organo-mercury species were stable for at least 30 days in all containers except those made of polyethylene; and Hg(o) was stable in all containers except those made of stainless steel or polyethylene. Hg(II) was rapidly lost from all containers except those made of aluminum, which rapidly converted it to Hg(o), which was stable. In general, most of the total Hg in petroleum products was particulate Hg, followed by dissolved Hg(II) and Hg(o). Sub-ng/g concentrations of methyl-Hg were observed in most samples.

Analysis of metals in condensates and naphthas by ICP-MS

Jan 1997
12

Olsen

Removal of Mercury from Process Streams

J Markovs

Determination of mercury species in gas condensates by on-line coupled HPLC and CVAA spectrometry

Jan 1995
29

Schickling

Process for Removing Mercury from a Gas or Liquid by Absorption on a Copper Sulfide Containing Solid Mass

A Sugier

Method of Eliminating Mercury or Arsenic From a Fluid in the Presence of a Mercury/Arsenic Recovery Mass

C Cameron

Process for Removing Mercury and Possibly Arsenic in Hydrocarbons

Roussell

Mercury Attack of Brazed Aluminum Heat Exchangers in Cryogenic Gas Service

D Nelson

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Abstract

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