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... The occurrence of dissolved organic and inorganic pollutants in aquatic environment is a serious global problem that raises both public awareness and scientific concern in recent decades [1,2]. For example, natural arsenic pollution of drinking water supplies has been reported in over 70 countries, posing serious risk to human health of at least 150 million people [3]. The toxicity of arsenic species is highly dependent on their valence states and chemical speciation [4]. ...
... As it can be seen, a stepwise nucleophilic substitution of chlorine by successive hydroxyl radical attack was proposed in pathway 1, yielding 3-(3-hydroxy-4-chlorophenyl)-1,1-dimethylurea (products I) and 3-(3,4-dihydroxyphenyl)-1,1-dimethylurea (product II). Similar pathway of • OH nucleophilic substitution has been reported previously in the reaction of chlorotoluron with • OH in the presence of NO 3 − under sunlight irradiation [51] and in UV illuminated TiO 2 suspensions [52]. The positions in diuron molecular structure for • OH attacking could be predicted based on the calculated frontier electron densities [53]. ...
... Human activities are the cause of most of the arsenic contamination in the aquatic environment, with industrial activities causing the most obvious contamination (Murray et al. 2023). Arsenic contamination poses a threat to surface water ecosystems (e.g., rivers and lakes), with the drinking water obtained directly from such contaminated water sources posing a Responsible Editor: Ioannis A. Katsoyiannis health risk to more than 150 million people globally (Kay 2011). Arsenic is highly toxic and enters the human body through the respiratory, skin, and gastrointestinal tracts, leading to a variety of diseases, including cardiovascular disease, cancer, and other diseases that pose serious risks . ...
Micro-nanobubbles (MNBs) can form reactive oxygen species (ROS) with high oxidizing potential. In this study, nickel-doped metal–organic framework materials (MOFs) capable of activating molecular oxygen were synthesized using trivalent arsenic (As(III)) as a target pollutant and combined with peroxymonosulfate (PMS) to construct a MOF/MNB/PMS system. The results included the rapid oxidation of As(III), the successful absorption of oxidized As(V), and finally the efficient removal of As. The effects of pH, amount of PMS used, and preparation time of MNBs on the As removal performance of the MOF/MNB/PMS system were investigated experimentally. The changes in the properties of the materials before and after the reaction were analyzed by XPS, and it was found that the main active sites on the surface of the MOFs were the metal elements and the pyridine nitrogen near the carbon atom. The regular morphology and elemental composition of the MOFs were determined by TEM scanning and EDS test, which indicated the presence of nickel. XRD tests before and after the reaction showed that the MOFs were structurally stable. The results of the free radical burst experiments show that the single linear oxygen (¹O2) is the main active substance in the system, and that the MNBs are key factors by which the system achieves efficient oxidation performance. In addition to providing a sustainable supply of molecular oxygen to the MOFs during the reaction process, coupling the MNBs with PMS was found to improve the oxidation capacity of the system. The results of this study thus provide a new concept for As removal and advanced oxidation in water bodies.
... The EU Drinking-water Directive sets the maximum concentration of As as 10 lg/L to reduce health risk. However, water in many places around the world exceed this threshold [122]. The frequently-used methods to remove As are the coagulation-co-precipitation and adsorption using Al-based material. ...
With the largest molecule size, most surface charge and highest polymerization degree among Al species with known structure, Al30 ([(AlO4)2Al28(OH)56(H2O)26]¹⁸⁺) has been attached increasing importance to various fields, including water treatment. Based on the relevant literatures in the past decades, this review tries to comprehensively elaborate the historical development of Al30, ranging from its discovery and formation, structure and physicochemical property, to potential application. Different from Al13 ([AlO4Al12(OH)24(H2O)12]⁷⁺), there is semi-pore geometry structure in Al30 central beltway, and hence the uneven distribution of surface electrostatic potential, which was more positive in beltway than that at cap. Meanwhile, Al30 exposed different-type oxygen functional groups, and the bound H2O located near the beltway was most acidic, making it most easy to deprotonate. The deprotonation and aggregation of Al30 occurred in similarly successive pattern, but the formed Al30 aggregate maintained positive charge within a wider pH range than Al13 aggregate. Moreover, Al30 is advantageous in high structural stability, which makes it intact under acidic or high-temperature condition. These unique characteristics facilitate the coagulation performance of Al30 towards organic matter, arsenic and microorganism by enhanced adsorption, charge neutralization and complexation. Meanwhile, with Al30, the effective dosage range was broader than that with Al13, and the coagulation process was more resistant to pH variation, which was beneficial to overcome the water quality fluctuation in actual water treatment. Another application of Al30 is the usage as pillaring agent to improve the adsorption and catalysis performance of clay. Finally, this review identifies the challenge and direction in the future development of Al30, including the improvement of characterization and quantitative methods, and pilot-scale investigation in actual water treatment.
... rivers and lakes) through both natural and anthropogenic activities (Weber et al., 2010;Zhang et al., 2018a). Drinking water directly derived from such contaminated sources poses a human health risk for more than 150 million people globally (Kay, 2011). Moreover, the bioaccumulation (Zavala and Duxbury, 2008) and magnification (Huang, 2016) of As through aquatic foods web, and uptake it by crops through irrigation with As-contaminated water (Natasha et al., 2021) also significantly contribute to public health issues. ...
The arsenic (As)-bearing eutrophic waters may suffer from the dual conditions of harmful algal blooms and release of As, driven by algal-induced hypoxia/anoxia. Here, we investigate the use of interfacial oxygen (O2) nanobubble technology to combat the hypoxia and control As exposure in simulated mesocosm experiments. It was observed that remediation of algal-induced hypoxia at the sediment-water interfaces (SWI) by application of O2 nanobubbles reduced the level of dissolved As from 23.2 μg L⁻¹ to <10 μg L⁻¹ and stimulated the conversion of As(III) to the less toxic As(V) (65–75%) and methylated As (10–15%) species. More than half of the oxidation and all the methylation of As(III) resulted from the manipulation by O2 nanobubbles of microbes responsible for As(III) oxidation and methylation. Hydroxyl radicals were generated during the oxidation of reductive substances at the SWI in darkness, and should be dominant contributors to As(III) abiotic oxidation. X-ray absorption near-edge structure (XANES) spectroscopic analysis demonstrated that surface sediments changed from being sources to acting as sinks of As, due to the formation of Fe-(hydr)oxide. Overall, this study suggests that interfacial O2 nanobubble technology could be a potential method for remediation of sediment As pollution through the manipulation of O2-related microbial and geochemical reactions.
... Arsenic poisoning includes blackfoot disease, peripheral neuropathy, encephalopathy and so on (Rahman et al., 2018). Well-known for its acute toxicity for hundreds of years, As pollution is a global issue affecting the health of general population (Kay, 2011;Li et al., 2017;Jeon et al., 2018;Khan and Bakar, 2019;Palansooriya et al., 2020). Yunnan Province is an important non-ferrous metal production center in China with a long history of smelting sulfidic minerals. ...
Both thallium (Tl) and arsenic (As) bear severe toxicity. Brake fern (Pteris vittata L.) is well-known for its hyperaccumulation capacity of As, yet its role on Tl accumulation remains unknown. Herein, brake ferns growing near an As tailing site in Yunnan, Southwestern China are for the first time discovered as a co-hyperaccumulator of both Tl and As. The results showed that the brake ferns extracted both As and Tl efficiently from the soils into the fronds. The studied ferns growing on Tl and As co-polluted soils were found to accumulate extremely high levels of both As (7215-11110 mg/kg) and Tl (6.47-111 mg/kg). Conspicuously high bio-accumulation factor (BCF) was observed for As (7.8) and even higher for Tl (28.4) among these co-hyperaccumulators, wherein the contents of As and Tl in contaminated soils were 1240 ± 12 and 3.91 ± 0.01 mg/kg, respectively. The applied advanced characterization techniques (e.g. transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS)) indicated a preferential uptake of Tl(I) while simultaneous accumulation of As (III) and As(V) from the Tl(I)/Tl(III)-As (III)/As(V) co-existent rhizospheric soils. The findings benefit the phytoremediation practice and pose implications for managing and restoring Tl-As co-contaminated soils in other countries.
The present investigation is focused to develop a new type of solid waste based biosorbent, derived from the Cassia fistula pod biomass. The prepared biosorbent has been characterized through different techniques including field emission scanning electron microscopy, fourier transform infrared spectroscope and X-ray diffraction to investigate the physiochemical properties which are potential for the bioadsorbent application. The experiments have been performed considering four parameters namely; pH, biosorbent dose, initial concentration of As⁺³ and duration in the batch reactor. The experimental results have been analyzed using the design-expert software for the optimization of different parameters. The maximum removal of arsenic could be achieved ∼91% whereas monolayer adsorption capacity is found to be 1.13 mg g⁻¹ in 80 min at pH 6.0 and 30 °C by using 60 mg dose of bioadsorbent. The arsenic adsorption behavior of the bio-adsorbent has been well interpreted in terms of pseudo-first order and Freundlich model.
Being a fundamental issue regarding the sewage treatment, the heavy metals removal from industrial effluents has been subject to intense scrutiny in both of academic and practical worlds. The removal of pentavalent arsenic (As (V)), one of the most poisonous pollutants, was investigated using sodium persulfate and iron powder system activated by ferrous ions (Fe2+-ZVI-PS). As (V) could be effectively removed by Fe2+-ZVI-PS system in a timely fashion (minute scale) with high removal rates (more than 90.0%) over a wide range of pH (1–9) and concentration (20–100 mg/L). The removal of As (V) by Fe2+-ZVI-PS system integrated favorably with the pseudo-second-order reaction kinetics. Researches on X-ray photoelectron spectroscopy (XPS) demonstrated that the Fe2+-ZVI-PS system enables the removal of As (V) through the process of co-precipitation and adsorption. Our findings thus emphasized that Fe2+-ZVI-PS system should be an effective trigger to purifying arsenic from the environment. Our results indicated that Fe2+-ZVI-PS system could be an effective candidate for remediation of arsenic in the environment.
Arsenic contaminated ground water is a serious public health issue, and recent estimates place 150 million people worldwide at risk. Current chemical field test kits do not reliably detect arsenic at the lower end of the relevant range, and may generate toxic intermediates and waste. Whole-cell biosensors potentially provide an inexpensive, robust and analyte-specific solution to this problem. The second generation of a Bacillus subtilis -based arsenic biosensor, designated Bacillosensor-II, was constructed using the native chromosomal ars promoter, arsR and the reporter gene xylE encoding catechol-2,3-dioxygenase. Within four hours, Bacillosensor-II can detect arsenic in the form of arsenate (AsO 4³⁻ ) at levels more than one order of magnitude below the recommended safe limit for drinking water suggested by the World Health Organisation (10 μg/L). Detection is reported by the enzymatic conversion of the inexpensive substrate catechol to 2-hydroxy- cis,cis -muconic semialdehyde, a bright yellow product visible by eye. We hope that this work will aid in developing a simple inexpensive field test kit for screening of drinking water for arsenic contamination.
Large-scale groundwater contamination by arsenic (As) requires economical yet reliable analytical procedures to monitor the quality of well water and the effluent of As elimination processes. The silver diethyldithiocarbamate (AgDDTC) method provides the basis of a series of colourimetric tests used as a compromise between semi-quantitative field-test kits and expensive instrumental analytics. This study aimed at understanding the significant As overestimation by the AgDDTC method observed in landfill leachate samples. Results of the AgDDTC test were up to threefold the levels obtained by reference analyses. Overestimation broadly agreed with the time course of chemical oxygen demand and total phosphorus in the leachate. We hypothesised that the interference was caused by reduced P species or humic acid (HA), respectively. To test this, As-AgDDTC determinations from As standards were conducted with phosphonic (H3PO3) and phosphinic acid (H3PO2) as well as two commercial HA as matrix components. While H3PO3 showed no effect, H3PO2 in concentrations of 0.06 to 28 mg P L−1 yielded As recoveries of up to 130%. This was probably due to the evolution of phosphine (PH3) as suggested by the absorption spectra recorded after reacting pure PH3 with AgDDTC in pyridine. The HA in concentrations of 0.6–320 mg dissolved organic carbon L−1 gave As recoveries of up to 600%, possibly due to a chromophoric reaction of volatile HA digestion products formed during the reduction step. Significant As overestimation in the presence of the above-named compounds may require pre-oxidation of the samples. To recognise interference effects, the acquisition of full absorbance spectra may be recommendable in lieu of fixed wavelength analyses.
Arsenic in soil and groundwater 9 Bio-geochemical interactions, health effects and remediation Elsevier
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- A B Mukherjee
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- Welch