Article

Highly Selective Adsorption of Vanadium (V) by Nano-Hydrous Zirconium Oxide-Modified Anion Exchange Resin

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Abstract

Adsorption is widely used in removal of toxic vanadium (V) [V(V)] from water streams, and a fit-for-purpose adsorbent plays a vital role in this process. Herein HZrO@D201, an adsorbent with decoration of nanosized hydrous zirconium oxide (HZrO) on anion exchange resin D201, is fabricated for efficient V(V) removal. Compared to pristine D201, HZrO@D201 excelled in V(V) removal with a maximum adsorption capacity of 118.1 mg/g, due to potential formation of inner sphere complexation between V(V) and HZrO. HZrO@D201 could also functioned well in a wide pH range (3.00 to 9.00) and exhibited outstanding selective V(V) adsorption under the presence of competing anions (chloride, nitrate, sulfate, and phosphate). The adsorption thermodynamics was in accordance with the Langmuir model, while adsorption kinetics followed the Pseudo-Second-Order model. When treating actual vanadium contaminated groundwater from Panzhihua region (China), HZrO@D201 indicated a satisfactory lifespan in the column experiment for V(V) removal (2.41 times longer than D201), and the treated groundwater could meet the vanadium standard of drinking water source in China (less than 50 μg/L). Regeneration of HZrO@D201 was easily achievable with negligible capacity loss. Results from this work suggests a promising application potential of HZrO@D201 in vanadium pollution control.

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... 1,2 As one of the most important catalytic metals in modern technology, vanadium is widely used in iron and steel industry, pharmaceutical engineering, ceramics, aviation, nuclear technology, and other fields. 3,4 Intensive production and application result in ever-growing vanadium contents in the environment. 5 For instance, about 10 mg/L vanadium has been detected in groundwater from a vanadium smelter in China. ...
... The XRD spectrum was cluttered, with hardly any obvious characteristic peaks (Figure 2c), indicating that the produced precipitates were amorphous. The possible products might be vanadyl phosphates, such as the bluish-green mineral, sincosite [CaV 2 (PO 4 ) 2 (OH) 4 ·3H 2 O]. 3 Digestion experiment results showed that Ca 2+ , dissolved V, and PO 4 3were all detected in the solution, confirming the formation of sincosite. Thermodynamics equilibrium calculation revealed that its formation occurred spontaneously (Text S1, Supporting Information). ...
... These results prove that bioaugmentation or accompanied biostimu-lation can be performed based on L. raf f inolactis to bioremediate the V(V)-contaminated environment satisfactorily in practice. 73−77 There are Ca 2+ and PO 4 3− in natural groundwater, 78 thus the produced V(IV) from V(V) reduction by L. raff inolactis can react with these ions to form insoluble sincosite in an actual groundwater environment during bioremediation. ...
Article
Whereas prospects of bioremediation for a vanadium(V) [V(V)]-contaminated environment are widely recognized, reported functional species are extremely limited, with the vast majority of Gram-negative bacteria in Proteobacteria. Herein, the effectiveness of V(V) reduction is proved for the first time by Lactococcus raffinolactis, a Gram-positive bacterium in Firmicutes. The V(V) removal efficiency was 86.5 ± 2.17% during 10-d operation, with an average removal rate of 4.32 ± 0.28 mg/L·d in a citrate-fed system correspondingly. V(V) was bio-reduced to insoluble vanadium(IV) and distributed both inside and outside the cells. Nitrite reductase encoded by gene nirS mainly catalyzed intracellular V(V) reduction, revealing a previously unrecognized pathway. Oxidative stress induced by reactive oxygen species from dissimilatory V(V) reduction was alleviated through strengthened superoxide dismutase and catalase activities. Extracellular polymeric substances with chemically reactive hydroxyl (−OH) and carboxyl (−COO–) groups also contributed to V(V) binding and reduction as well as ROS scavenging. This study can improve the understanding of Gram-positive bacteria for V(V) bio-detoxification and offer microbial resources for bioremediation of a V(V)-polluted environment.
... The PSO model was the best for modelling the experimental data (R 2 > 0.99) of vanadium adsorption by nanosized TiO 2 and ZnO oxides and the rate removal process rate was dominated by chemical adsorption [49]. Vanadium adsorption on nanosized hydrous zirconium dioxide (HZrO) using the anion exchange resin D201 (HZrO@D201) [50] and polypyrrole coated magnetized natural zeolite [21] follows also the PSO model. ...
... The desorption of vanadium is possible due to an increase of repulsion forces between the vanadium cations and the positive surface of the adsorbent in the HCl medium. Li et al. [50] applied the mixture of 5% NaOH + 10% NaCl for vanadium ions desorption from the nano-hydrous zirconium dioxidemodified anion exchange resin obtaining the 91.2% desorption. Elution of vanadium ions from aluminum and zirconium dioxides was also made by Kosta et al. [55]. ...
Article
It is well known that removal of vanadium ions from the natural environment has become a great challenge in recent years. Due to this fact, the present study concerns the application of binary oxides such as TiO2-ZrO2 (molar ratio 9:1) and TiO2-ZnO (molar ratio 7:3) synthesized by the sol-gel method with calcination at 873 K (TZ1 sample) or by the hydrothermal method at 433 K (TZ2 and T7Zn3 samples), respectively. The fabricated adsorbents were subjected to the detailed physicochemical analysis including: dispersive properties, morphology, crystalline and textural properties as well as chemical composition. The vanadium(V) ions adsorption on the binary oxides was optimized by the experimental conditions such as pH (2-10), adsorbent dose (0.01-0.1 g), vanadium concentration (10-500 mg/L), agitation time (1 min-24 h) and temperature (293-333 K). The pseudo-first-order (PFO), pseudo-second-order (PSO) and intraparticle diffusion (IPD) kinetic models as well as the Langmuir, Freundlich, Temkin and Dubinin-Raduskievich isotherm models were applied for the description of V(V) adsorption. The adsorption capacities were found to be 129.3 mg/g for TZ1, 170.8 mg/g for TZ2 and to 195.9 mg/g for T7Zn3. The endothermic and spontaneous character of V(V) adsorption on the binary oxides was confirmed by the values of thermodynamic parameters. The best fitting of kinetic experimental data to the pseudo-second-order model was obtained. The maximum desorption yield (%D) was achieved using the 1 mol/L NaOH (97.96%-T7Zn3, 75.81%-TZ2, 62.88%-TZ1) solution. Applicability of the inorganic oxides in V(V) and Fe(III) removal from spent catalyst leaching solutions was proved.
... This might be because, in alkaline conditions, there is competition between OH − and PO 4 3− ions for attaching to the surface of the sorbent, leading to reduced sorption of phosphate. Li et al. [384] fabricated an anion exchange resin D201, with nanosized hydrous zirconium oxide (HZrO) for successful removal of vanadium(V). Favorable sorption capacity of 118.1 mg/g was achieved for the removal of V(V), confirming the excellent capability of the prepared HZrO@D201HZrO@D201 sorbent. ...
Article
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Nanotechnology has emerged as an extraordinary and rapidly developing discipline of science. It has remolded the fate of the whole world by providing diverse horizons in different fields. Nanomaterials are appealing because of their incredibly small size and large surface area. Apart from the naturally occurring nanomaterials, synthetic nanomaterials are being prepared on large scales with different sizes and properties. Such nanomaterials are being utilized as an innovative and green approach in multiple fields. To expand the applications and enhance the properties of the nanomaterials, their functionalization and engineering are being performed on a massive scale. The functionalization helps to add to the existing useful properties of the nanomaterials, hence broadening the scope of their utilization. A large class of covalent and non-covalent functionalized nanomaterials (FNMs) including carbons, metal oxides, quantum dots, and composites of these materials with other organic or inorganic materials are being synthesized and used for environmental remediation applications including wastewater treatment. This review summarizes recent advances in the synthesis, reporting techniques, and applications of FNMs in adsorptive and photocatalytic removal of pollutants from wastewater. Future prospects are also examined, along with suggestions for attaining massive benefits in the areas of FNMs.
... Acute vanadium poisoning can lead to the damage of heart, kidney, gastrointestinal and central nervous system Liu et al. 2017;Xu et al. 2015). Once the vanadium concentration in the groundwater is rose, it will be a threat to the living organisms when such groundwater is used as a main drinking water source (Hao et al. 2021;Li et al. 2020b). Compared with other heavy metals, vanadium is more toxic due to its strong oxidative damage to the cells. ...
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Vanadium chemicals, known as the “vitamins of the modern industry,” are major resources widely used in the petroleum, steel, batteries and catalyst industry. Vanadium is also essential in biological systems. Here we review vanadium properties, mineral sources and recovery methods such as blank, sodium and calcium roasting, water, acidic and alkaline leaching, hydrolysis, ammonium precipitation, adsorption, solvent extraction and ion exchange. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
... Vanadium resources occur worldwide in mineral and hydrocarbon deposits, with China, South Africa, and Russia the largest producers of vanadium products (Moskalyk and Alfantazi, 2003;Yu et al., 2019). Increasing demand for vanadium has promoted intensive mining and smelting activities Li et al., 2020). For example, hundreds of vanadium smelters at different scales are distributed throughout the provinces of China . ...
Article
Whereas there is broad consensus that smelting causes serious soil contamination during vanadium production, little is known about the vanadium content of soil near smelters and the associated health risk at continental scale. This study is the first to map the distribution of vanadium in farmland soil surrounding smelters throughout mainland China, and assess the associated health risk. Analysis of 76 samples indicated that the average vanadium content in such soil was 115.5 mg/kg – far higher than the 82 mg/kg background content in China (p < 0.05). Southwest China (198.0 mg/kg) and North China (158.3 mg/kg) possessed highest vanadium contents. Vanadium content was strongly related to longitude, altitude, and atmospheric temperature. The reducible fraction accounted for the largest percentages in vanadium speciation. The average Pollution Load Index for all samples was 1.51, denoting significant metal enrichment. The Children's hazard index was higher than unity, indicating elevated health risk. The relative contribution of vanadium to the total health risk ranged from 6.02% to 34.5%, while nickel and chromium were the two main contributors in most regions. This work may serve as a model providing an overview of continental vanadium contamination around smelters, and draw attention to their possible health risks.
... Vanadium becomes toxic that cause pneumonia, developmental abnormalities, lung bleeding and even death at high concentrations [5,6]. A minimum reporting level of 0.2 μg/L in drinking water for vanadium is proposed by US Environmental Protection Agency [7]. Chromium is another toxic metal with public health goal of 0.02 μg/L issued by Office of Environmental Health Hazard Assessment at California, USA. ...
Article
Vanadium and chromium co-exist commonly with elevated levels in groundwater at vanadium smelting sites. While bioremediation has been recognized promising for this co-contamination treatment in aquifer, interactions during vanadium (V) [V(V)] and chromium (VI) [Cr(VI)] bio-reductions under autotrophic condition remain largely unknown. In this study, efficient reductions of V(V) and Cr(VI) from synthetic groundwater were realized simultaneously in a continuous flow autotrophic sulfur-based biosystem, with more than 85% overall removals under hydrochemical and hydrodynamic fluctuations during 276-d operation. Soluble Cr(VI) was reduced to insoluble Cr(III) preferentially, while reduction of soluble V(V) to insoluble V(IV) was easily inhibited. Elemental sulfur [S(0)] was bio-oxidized to sulfate. Analyses of carbon isotope, microbial community and metabolic pathway revealed the synergetic mechanisms. Autotrophs (e.g., Sulfuricurvum) utilized energy released from S(0) oxidation to synthesize volatile fatty acids (VFAs), which were consumed by heterotrophic V(V) and/or Cr(VI) reducers (e.g., Geobacter). Functional genes responsible for S(0) oxidation and reduction of V(V) and Cr(VI) were detected. V(V) and Cr(VI) reductions were catalyzed by both cytochrome c and nicotinamide adenine dinucleotide. VFAs were also transformed to glycogen in cells to store energy. Robust remediation strategy is thereby proposed for aquifer co-contaminated by V(V) and Cr(VI).
... Vanadium is a strategically important metal in modern world (Crans et al., 2004;Liu et al., 2017;Shaheen et al., 2019). Long record of anthropogenic activities has raised its environmental concerns, mainly attributed to intensive mining and smelting operation to meet the industrial demand (Chai et al., 2010;Li et al., 2020a). Chronical exposure under excessive vanadium level may lead to adverse health impact such as asthma, rhinitis, and increased possibility in lung cancer Rinklebe et al., 2019). ...
Article
Whereas the adverse effects of vanadium released from smelting activities on soil microbial ecology have been widely recognized, little is known about spatiotemporal vanadium distribution and microbial community dynamics in typical contaminated sites. This study describes vanadium contents associated with health risk and microbial responses in both topsoil and subsoil during four consecutive seasons around an ongoing-production smelter in Panzhihua, China. Higher levels of vanadium concentration exceeding soil background value in China (82 mg/kg) were found close to the smelter. Vanadium concentrations decreased generally with the increase in distance to the smelter and depth below surface, as soil vanadium pollution is induced mainly by atmospheric deposition of vanadium bearing dust during smelting. Residual fraction was the predominated vanadium form in soils, with pronounced increase in bioavailable vanadium during rainfall period due to frequent drought-rewetting process. Topsoil close to the smelter exhibited significant contamination, inducing high probability of adverse health effects. Spatiotemporal vanadium distribution creates filtering effects on soil microorganisms, promoting metal tolerant genera in topsoil (e.g. Microvirga) and subsoil (e.g. Bacillus, Geobacter), which is the key in maintaining the community structure by promoting cooperative relation with other taxa. Our results reveal spatiotemporal vanadium distribution in soils at site scale with potential health risk and microbial responses, which is helpful in identifying severe contamination and implementing bioremediation.
... Vanadium (V) is widely used in modern society because of its excellent properties (Li et al., 2020a;Watt et al., 2018;Zhang et al., 2012). V smelting activities are ever-growingly intensive, releasing large amounts of toxic metals such as V, zinc (Zn), copper (Cu) into air concurrently through high-temperature volatilization (Lv et al., 2018;Schlesinger et al., 2017), which is also the main source of surrounding soil contamination (Xiao et al., 2017;Zhang et al., 2019a). ...
Article
Heavy metals (HMs) such as vanadium (V), zinc (Zn), arsenic (As), chromium (Cr), copper (Cu) and nickel (Ni) are released into atmosphere during V smelting activities, resulting in their co-existence with airborne microbes. However, little is known about HMs distributions and associated microbes in aerosols from such industrial districts. This study reveals seasonal dynamics of HMs and microbes in ambient aerosols from V smelter in Panzhihua, China. Multiple HMs were detected, while V concentration was the highest, maximizing at 228.0 ± 10.3 ng/m³ in Spring. Health risks displayed similar trends to HMs distributions, and children were posed much higher risks than adults due to their more sensitivity to HMs. V and As contributed dramatically to total health risks among all examined HMs. High-throughput 16S rRNA gene sequencing analysis revealed microbes tolerant to V, Zn, As, Cr, Cu and Ni. Acinetobacter widely existed with function of detoxifying V(V) and more species as Bacillus, Gobacter and Thauera tolerating V, Zn, As, Cr, Cu and Ni appeared in Summer. These findings shed light on understandings of HMs dynamics and associated microbial community in aerosols from smelting regions.
... per each gram at a saturation state. The data presented in Table 4 shows that the synthesized nanocomposite has an acceptable and comparable ability to other adsorbent suggested for vanadium separation from aqueous solution (Namasivayam and Sangeetha 2006;Mthombeni et al. 2016;Manohar et al. 2005;Cadaval Jr et al. 2016;Naeem et al. 2007;Bhatnagar et al. 2008;Liao et al. 2008;Erdem et al. 2011;Gan et al. 2020;Sirvio et al. 2016;Padilla-Rodriguez et al. 2015;Anirudhan and Radhakrishnan 2010;Anirudhan et al. 2009;Gupta et al. 2017;Fan et al. 2020;Ghanim et al. 2020;Zhu et al. 2020;Chen et al. 2020;Li et al. 2020;Zhu et al. 2018;Shahat et al. 2019;Zhang and Leiviska 2020;Kong et al. 2020;Salehi et al. 2020). As the data presented in Table 4 shows, the adsorption capacity of SiO 2 /CH/Fe nanocomposite is higher than the other adsorbents proposed for adsorption of vanadium, except for 5 adsorbents. ...
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The husk of brown rice, as a source of silica, was applied to synthesize natural SiO2 nanoparticles via sonochemical method. SiO2/CH/Fe nanocomposite was synthesized from SiO2, chitosan (prepared from shrimp shells via sonochemical method), and iron functional groups and detected using BET, EDX-SEM, and FTIR techniques. These natural-based nanostructures (SiO2 and SiO2/CH/Fe) have been applied for vanadium adsorption. The influences of initial pH, initial concentration, and adsorption time were studied via a batch process. The analysis of the kinetics data indicated that the chemical adsorption is predominant. The analysis of the equilibrium data indicated the single layer and exothermic adsorption process. The mono-layer adsorption capacity of SiO2/CH/Fe was 199.540 mg g⁻¹. The performance of SiO2/CH/Fe in a continuous column system was investigated in four adsorption and desorption cycles. Results showed that SiO2/CH/Fe nanocomposite synthesized with the sonochemical method is a candidate with high adsorption ability for use as an industrial adsorbent.
... The effect of initial pH on the sorption of Hg(II) ions onto utilized nano particles was evaluated within the pH range of 2.6-9.53. The metal removal from solution at pH beyond 10 would not give accurate results because precipitation of the ions as hydroxides took place, that was the reason the removal curve became high as there were not mercury ions to be removed (the solution seems to be clear because of the metal precipitation)[79]. The effect of different pH values ranged from 2.6 to 9.53 on the adsorption of Hg(II) by Al 2 O 3 (E 800 ) and PANAA / (E 800 ) nanocomposites (1 g/L) for 24h contact time was investigatedFig. ...
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The synthesis, characterization and capacity studies of co-polymerized Al 2 O 3 nanocomposites capable of adsorbing with Hg(II) ions are reported. Al 2 O 3 nanoparticles was fabricated with combustion synthesis using inexpensive mixed fuels. Nanocomposite of poly (aniline-CO-O-anthranilic acid) (PANAA/ Al 2 O 3 ) was synthesized by chemical oxidative polymerization of anthranilic acid and aniline co-monomers at equimolar ratios (1:1) with the Al 2 O 3 nanostructure. The product was characterized by FT-IR, XRD, SEM and TEM techniques. The adsorption behaviors of the toxic Hg(II) were studied. The equilibrium isotherm, kinetics parameters and the thermodynamics investigations of the adsorption process were calculated. Thermodynamics investigations also confirmed that the adsorption capacity of Hg(II) on each adsorbent was spontaneous and exothermic.
... Vanadium resources occur worldwide in mineral and hydrocarbon deposits, with China, South Africa, and Russia the largest producers of vanadium products (Moskalyk and Alfantazi, 2003;Yu et al., 2019). Increasing demand for vanadium has promoted intensive mining and smelting activities Li et al., 2020). For example, hundreds of vanadium smelters at different scales are distributed throughout the provinces of China . ...
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Heavy metal contamination, particularly vanadium contamination in mining and smelting areas, is a worldwide serious problem threatening the ecological system and human health. The contamination level of vanadium, arsenic, cadmium, chromium, mercury, and lead in sediments and waters in a vanadium mining area in China was investigated in the present study. The behavior of heavy metal uptake by 12 native aquatic macrophytes was evaluated, including 5 species of emergent aquatic plants (Acorus calamus, Scirpus tabernaemontani, Typha orientalis, Phragmites australis, and Bermuda grass), 3 species of floating plants (Marsilea quadrifolia, Nymphaea tetragona, and Eleocharis plantagineiformis), and 4 species of submerged plants (Hydrilla verticillata, Ceratophyllum demersum, Myriophyllum verticillatum, and Potamogetom crispus). Different heavy metal accumulation abilities were found across these macrophytes. Generally, they tended to accumulate higher contents of chromium, and C. demersum showed a particularly higher accumulation capacity for vanadium. The heavy metals were preferentially distributed in roots, instead of translocation into leaves and stems, indicating an internal detoxification mechanism for heavy metal tolerance in macrophytes. In 24-day laboratory hydroponic experiments, the macrophytes had a satisfied phytoremediation performance for heavy metals, when their concentrations were at the microgram per liter level. Particularly, vanadium was effectively removed by P. australis and C. demersum, the removal efficiencies of which were approximately 50%. In addition, a combination of terrestrial plant (Bermuda grass) and aquatic macrophytes (P. australis, M. quadrifolia, and C. demersum) exhibited high uptake capacity of all the six heavy metals and their residual concentrations were 95 (vanadium), 39.5 (arsenic), 4.54 (cadmium), 17.2 (chromium), 0.028 (mercury), and 7.9 (lead) μg/L, respectively. This work is of significant importance for introducing native macrophytes to remove low-level heavy metal contamination, particularly vanadium, and suggests phytoremediation as a promising and cost-effective method for in situ remediation at mining sites.
... 16 The acid leaching solution containing vanadium was obtained by sulfuric acid leaching or hydrochloric acid leaching, which could also contain a certain amount of metal impurity ions needing to be separated and purified. 1,17,18 At present, the solvent extraction process was a usual mature method for the separation and purification of vanadium from acidic solution. 19−21 There are many studies on the extraction and separation of vanadium from the sulfuric acid leaching solution system, in which extractants such as P204, P507, Cyanex272, TOMAC, TOMAC, Aliquat 336, and other ionic liquids were used for the extraction and separation of vanadium from iron, aluminum, and other impurity ions, in which the extraction mechanism was also reasonably analyzed. ...
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Hydrochloric acid leaching has been widely used in the recovery process of vanadium due to its efficient selectivity. It was necessary to further separate vanadium from hydrochloric acid leaching solution. Four extractants of P204, P507, Cyanex272, and N1923 were compared for extraction of vanadium from a simulated hydrochloric acid solution, and it is concluded that N1923 was an effective extractant suitable for the extraction and separation of V (V) in the medium. The single-stage extraction efficiency of vanadium reached more than 90% with a pH value of 2.0, extraction time of 5 min, and X N1923 of 0.2 at 30 °C. The functional group characteristics of the extraction complex were analyzed by means of an extraction slope method, FT-IR, and 1H NMR to judge the extraction mechanism of vanadium with N1923 as an extractant. The extraction of V (V) by using N1923 was in the coordination form of a molar ratio of 2:1, and the extraction process was an endothermic reaction. The N-H vibrational absorption peak in the -NH2 group still appeared in the loaded N1923, in which the chemical shift of 1H in the primary amine and secondary carbon still existed. This technology was a more efficient process for extraction of vanadium from hydrochloric acid solution.
... Moreover, the reduction in the speed of the process is clearly visible. The reason for such changes in the adsorption process is the fact that all tested interfering ions and V(V) are anions at the tested pH, which results in competition for active sites on the adsorbent [34]. ...
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This study investigated the adsorption behaviors of chlorate and chlorite by MIEX resin, and the optimal conditions of removal rate using the response surface methodology. Chemical properties of the solution, such as pH, coexistent anions and ion strength, has great influence on adsorption of chlorate and chlorite. When pH tends to neutral, the removal rate of chlorate and chlorite on MIEX is the best. Sulfate radical has a damaging influence on the adsorption of chlorate and chlorite on MIEX for the low adsorption capacity. The initial adsorption kinetics of chlorate and chlorite adsorption on MIEX follows the intra-particle diffusion-controlled adsorption. Box-Behnken design method is successfully used to establish a quadratic polynomial mode for predicting the removal efficiency of chlorate and chlorite, which is composed of three variables (absorbent dosage, reaction time and initial concentration). According to the results, the adsorbent dosage had a strong interaction with chlorate or chlorite concentration and reaction time, which has a significant impact on the optimization of chlorate and chlorite removal process by MIEX. From the FTIR, the adsorption mechanisms is anion exchange in the chlorate and chlorite.
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The influence of silicate on the structural memory effect of layered double hydroxides (LDHs) has been rarely reported. In this study, five kinds of calcined LDHs (CLDHs) were synthesized and used as adsorbents for the sorption of selenium with or without silicate, under the initial pH 10 and 13, respectively, characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption isotherm. The results indicated that silicate can significantly affect the phase transformation of CLDHs, and the sorption amounts of selenite and selenate dramatically decreased in the presence of silicate. Specifically, silicate can react with MgO and Al2O3 in CLDHs to generate magnesium silicate hydrate and geopolymer-like substance which were covered on the surface of particles, blocking the hydroxylation of metal oxides. However, higher pH suppressed the interaction between MgO and silicate and enhanced the formation of geopolymer-like substance, which promoted the regeneration of LDHs. Al in CLDHs plays a critical role in the regeneration of LDHs. Besides, the ternary oxides (CLDH-2, Mg2Fe0.33Al0.67-oxide; CLDH-3, Mg2Fe0.5Al0.5-oxide) possessed larger specific surface areas (127.7 and 158.2 m²/g) and consequently presented more resistance to the effect of silicate.
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This work demonstrates that floccules of hydroxides and zinc oxides (Zn(OH)2 and ZnO) can be produced with an optimal surface electrical charge to adsorb vanadium complexes, when using zinc anodes and selecting appropriate electrocoagulation process conditions. It was found that the electrical charge of the floccules was mainly controlled by chemical and complex species that are a function of the pH and ionic strength in the suspension. At a pH of 7.0 and a concentration of 0.01 M NaCl, the floccules got a positive electric charge (+24.75 mV) and readily adsorbed negatively charged vanadium complexes. The highest adsorption capacity of floccules produced with zinc anodes was 112.08 mg/g (for V(III)) and 158.76 mg/g (for V(V)) with an equilibrium time of 20 minutes. The floccules, before and after the adsorption of vanadium complexes, were characterized to identify the formation of oxyhydroxides (Zn3(OH)2(V2O7)*2H2O) and zinc oxides (Zn3(VO4)2*3H2O). The optimal vanadium removal was obtained under the following experimental conditions: pH = 7.0, 50 mg/L of vanadium, 0.10 g/L of floccules, 25 °C, and 40 min of contact time between the floccules and the contaminated water. The percentage of vanadium removal were 97.4%, 89.76% and 66.08% for V(III) and 99.9%, 90.6% and 76.54% for V(V) while the concentration in the polluted water was 10, 30 and 50 mg/L, respectively. A pseudo–second–order model describes the vanadium adsorption kinetics. At 25 °C, the experimental data were well represented by the Freundlich isotherm, and the maximal vanadium adsorption capacity was 158.76 mg/g.
Article
The poly (methyl methacrylate) (PMMA)-based nanoparticle was synthesized by surfactant-free emulsion polymerization method and then post modified with Calixarene using (3-Aminopropyl)triethoxysilane organo-silane as a linker after OH-treatment. The prepared structure was applied for efficient adsorption of Vanadium ions in the aqueous solution after characterization by FT-IR, SEM, TEM, DLS, and EDX. Additional investigations discovered that the prepared adsorbent has a good capacity to adsorb vanadium ions. The effect of key experimental factors was studied to find the optimal point of adsorbent efficiency including the initial concentration of analyte, sorbent dosage, pH of the solution, contact time, and type/quantity of the eluents. It was specified, the maximum adsorption capacity for the synthesized nanoparticles was obtained about 322 mg g⁻¹. The adsorption mechanism was revealed that the model of Langmuir isotherm well-matched compared to the others due to the calculated equilibrium data. Besides, the kinetics of the adsorption process was fitted with pseudo-second-order. Eventually, the prepared adsorbent was successfully applied in vanadium adsorption from real water media.
Article
Groundwater vanadium (V) (V(V)) contamination is ubiquitous in vanadium mining/smelting region and development of novel strategy for its remediation is of particular significance. Herein woodchip-sulfur packed biological permeable reactive barrier (bio-PRB) is established towards successful V(V) bio-detoxification. V(V) removal was accelerated under such mixotrophic condition, compared with heterotrophic and autotrophic V(V) reductions. The performance of bio-PRB was relatively steady with V(V) removal efficiency of 68.5-98.2% in fluctuant geochemical and hydrodynamic environments. Microbial community analysis indicated that heterotrophic Geobacter was the main reducer to convert V(V) to insoluble V(IV), by employing organics from woodchip hydrolysis and sulfur anabolism of autotrophs (e.g., Sulfuricurvum and Thiobacillus). V(V) reduction and elemental sulfur oxidation were regulated by genes as omcA, omcB and mtrC and soxB, respectively. The elevated contents of cytochrome c and nicotinamide adenine dinucleotide implied the improved electron transfer, facilitating V(V) reduction. This study provides a cost-effective, robust and sustainable route to V(V)-polluted aquifer remediation.
Article
The novel hybrid adsorbents, which were composed of nanozeolite and nanochitosan ([email protected]) and nanozeolite-multi walled carbon nanotube and nanochitosan ([email protected]) were produced by simple method. The adsorption capacity of synthesized nanocomposites towards vanadium (V) was compared with that of a clinoptilolite-nanochitosan nanocomposite ([email protected]) obtained from natural zeolite. Zirconium (Zr) was employed to modify prepared nanocomposites because Zr (IV) has a strong affinity towards oxyanions such as V. Zr-modified nanocomposites and their pristine nanocomposites were comparatively characterized by different techniques. Batch experiments were conducted to find out the influence of different experimental factors. The adsorption capacities of all prepared materials towards V ions decreased with temperature increasing from 298 to 348 K. The calculated values of the thermodynamic parameters ΔH and ΔG demonstrated that the adsorption was exothermic and spontaneous. The adsorption process was described by the Freundlich isotherm and pseudo-second order model. The V species loaded nanocomposites could be regenerated by 0.5 M HCl–1.0 M thiourea solution. The adsorption performance was not considerably influenced by the coexistence of the nickel ( Ni²⁺) but nitrate (NO3⁻) and sulfate (SO4²⁻) revealed slightly greater negative effects. The as-prepared nanocomposites can be used in three adsorption cycles without specific changing its adsorption efficiency.
Article
Vanadium (V) in soils exerts toxic effects on human health. To develop a plant-microorganism combined remediation strategy for V-contaminated soil, pot experiments were conducted with alfalfa (Medicago sativa L.) and V-resistant bacterial strain Arthrobacter sp. 5k4-8-1 in different levels of V-contaminated soil. At 500 mg kg−1 spiked V(V), alfalfa survived only in the soils inoculated with high-level bacterial strain (10¹⁰ CFU mL−1, 15 mL), indicating that strain 5k4-8-1 worked effectively on alleviating the stress of V on plant growth. Compared with non-inoculated controls, the V accumulation in alfalfa plants was increased conspicuously by inoculation of strain 5k4-8-1. After the remediation process by the combination of strain 5k4-8-1 and alfalfa, the proportion of V(V) in total V decreased in all soils, indicating that the strain may possess a mechanism of reducing V(V) to V(IV). Moreover, the strain 5k4-8-1 led to an obvious reduction of soil V bioavailability and mobility in inoculation treatments. These results provide insights into the plant-microorganism combined bioremediation of V-contaminated soil.
Article
Vanadate [V(V)] and phenanthrene (PHE) commonly coexist in groundwater aquifer, posing potential threats to ecological environment and public health. However, little is known about the complicated biogeochemical processes involving microbial V(V) reduction coupled with co-metabolic PHE biodegradation. Herein we demonstrated that synchronous removal of V(V) and PHE could be realized under anaerobic condition. Complete V(V) removal and PHE degradation efficiency of 82.0 ± 0.8% were achieved in 7-d operation in batch experiment. 250-d continuous column experiment implied that hydrochemical condition affected V(V) and PHE removals. V(V) was reduced to insoluble vanadium (IV) and PHE was degraded into small molecule organics (e.g. salicylic acid). Geobacter and Acetobacterium used methanol and intermediates from PHE degradation as electron donors for V(V) reduction. PHE was decomposed by Mycobacterium and Clostridium with methanol as co-metabolic substrate and V(V) as electron acceptor. Genes encoding proteins for V(V) reduction (omcA, omcB and mtrC) and PHE degradation (phnAc) were upregulated. Cytochrome c and nicotinamide adenine dinucleotide promoted electron transfer for V(V) and PHE detoxification. Extracellular polymeric substances could bind V(V) and improve the bioavailability of PHE. Our findings provide a robust strategy for remediation of V(V) and PHE co-contaminated groundwater.
Article
The work demonstrates the effective utilization of hybrid Polyurethane - palladium doped zirconium oxide (Pd–ZrO2) as innovative carriers for corrosion protection coatings on steel materials. ZrO2 and Pd–ZrO2 nanoparticles were successfully synthesized using Photodeposition followed by the hydrothermal synthesis method. The synthesized nanoparticles were then incorporated into the polyurethane matrix and characterized using Fourier-transform infrared spectroscopy and scanning electron microscopy (SEM). The FTIR and SEM confirm the presence of ZrO2 and Pd–ZrO2 nanoparticles and their morphologies in polyurethane composites material. The thermogravimetric analysis (TGA) results indicated that the polyurethane matrix remained stable up to 250 °C. At 800 °C, >50% of residues are observed for Pd–ZrO2 – polyurethane in the TGA analysis, which confirms that the primer and nanoparticles addition enhances the thermal stability of the composite. The water contact angle measurement explains the hydrophobic behavior of nanocomposite modified coatings on a mild steel substrate. It indicates that Pd–ZrO2 and primer significantly increase the hydrophobicity of polyurethane. The major advantages of developing water-repellent or hydrophobic surfaces open up a world of possibilities for metals and alloys in terms of corrosion prevention. Electrochemical impedance spectroscopy (EIS) and a salt spray test were used to determine the anti-corrosion behavior of the prepared polymer nanocomposites. The polymer nanocomposite coatings have better anti-corrosive capabilities when compared to pure polyurethane. The corrosion protection efficiency increased from 76.63% to 97.57% upon incorporating 2 wt % of Pd–ZrO2 in the polyurethane matrix. The results confirmed that the modifications on the polyurethane enhanced the hydrophobicity and anti-corrosion properties of the polymer nanocomposite coatings.
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Acid leaching is an effective method to extract vanadium from polymetallic black shale. However, a large amount of metal impurities, especially iron and aluminum, which accompany vanadium, are released during this process. In this study, a aminophosphonic acid chelating resin was used for the differential adsorption and desorption of vanadium (V), iron (Fe), and aluminum (Al) ions to achieve deep separation and concentration of V ions present in the acid leaching solution of polymetallic black shale. Results showed that V adsorption efficiency reached 90.17% at a pH of 1.8. After differential adsorption and desorption, the V:Fe and V:Al concentration ratios increased from 1.84 to 64.53 and from 0.24 to 37.92, respectively. When a 2.5 mol/L NaOH solution was used as desorbent, the separation factors β(V/Fe) and β(V/Al) reached values of 694.22 and 452.29, realizing the selective separation and concentration of V. It was found that the V, Fe and Al ions were selectively adsorbed on the phosphonic acid functional groups (‐PO(OH)2) and amino functional groups (‐NH). The V ions existed in the form of the polyvanadate H2V10O284−, which can be directionally adsorbed on ‐PO(OH)2 under P‐OH bond cleavage and coordination of H2V10O284− to the unsaturated P atom and then desorbed through the exchange between hydroxide anions OH− and H2V10O284−. The Fe and Al ions cannot be desorbed by OH− because the Fe and Al sulfate moieties FeSO4+ and AlSO4+ were capable of coordinating to the nitrogen atom of the N‐H group via its lone electron pair. This article is protected by copyright. All rights reserved.
Article
Herein, hazardous solid particulate waste collagenic fibers (SWCFs) of leather industries were incorporated into apple pomace pectin (APPN)-grafted-pentapolymer, i.e., APPN-g-[sodium 2-methylidenebutanedioate (SMBD)-co-N-((3-(isopropylamino)-3-oxopropoxy)methyl)butyramide (CM1)-co-N-(hydroxymethyl)prop-2-enamide (NHMPE)-co-N-(hydroxymethyl)-4-(N-isopropylbutyramido)butanamide (CM2)-co-N-(propan-2-yl)prop-2-enamide NPYPE)/ PENP1], i.e., APPN-g-PENP1/ PENP2, prepared via one-pot facile polymerization of APPN and synthetic monomers, i.e., SMBD, NHMPE, and NPYPE, in aqueous medium, to fabricate an optimum multifunctional hybrid biocomposite adsorbent/ HCOM3. In PENP1, PENP2, and HCOM3, fourth/ CM1 and fifth/ CM2 multifunctional comonomers were anchored in situ. The structures of PENP1, PENP2, HCOM3, CM1, CM2, and metal-ion adsorbed HCOM3; APPN-grafting; SWCF incorporation; and surface properties were analyzed through NMR, XPS, FTIR, XRD, and SEM. The elevated adsorption efficiencies (AEs), reusability, thermostability, swelling, network durability, and crosslink density of HCOM3 were attributed to variable functionalities of SWCF/ APPN, explored by DLS and TGA, swelling, network, and thermodynamic parameters. Compared to SWCF, APPN, PENP1 and PENP2, the elevated AEs and reusability compelled HCOM3 as more suitable for scalable waste management. The maximum AEs, i.e., 171.79, 180.47, and 177.27 mg g–1, for Ti(IV), As(V), and V(V) at pHop = 7.0, 3.0, and 5.0, respectively, within 5–100 mg L–1 and at 298 K for 25 mg HCOM3 deteriorated during ternary adsorption by the antagonistic effects.
Article
The sulfuric acid leachate from vanadium-bearing shale (SALV) has high acidity with pH around 0.5, and contains several different elements. The chelating extractant Mextral 984H was proposed to extract vanadium from said leachate. In this study, the effects of pH, temperature, extraction time, phase ratio and Mextral 984H concentration on the vanadium extraction efficiency were investigated. Moreover, this has been appraised as well in regards to other impurities such as iron, aluminum, magnesium, potassium, phosphorus, and calcium. The results show that 99.55% of vanadium was extracted through a three-stage extraction, while concentration of extracted impurities was lower than 3%. These experiments were carried out at pH=0.53, temperature of 25℃, extraction time of 12 min, phase ratio (A/O) equal to 2:1, Mextral 984H concentration of 20 vol% and sulfonated kerosene as diluent. The extraction mechanism of vanadium was investigated using FT-IR, ¹H-NMR, ESI and quantitative calculations. It has been observed that the O atom on the phenolic hydroxyl and the N atom on the oximido were coordinated with V(V) to form an extraction complex composed of a six-membered ring with 1:1 (metal:ligand) mole ratio; interestingly, the H atom on the phenolic hydroxyl was dissociated. According to the reported results, the Mextral 984H extraction system can be used to extract vanadium from the SALV with no need to adjust pH, which can simplify the extraction process and reduce the consumption of chemicals.
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The presence of aromatic compounds with multiple functional groups such as 5-sulfosalicylic acid (SSA) in water bodies is a threat to aquatic organisms and human health. Phenol (PH) with the -OH group, benzoic acid with -COOH and benzenesulfonic acid (BSA) with -SO3H can be considered as SSA structural unit. In this study, three functional monomers, namely, N-methylallylamine, diallylamine, and triallylamine, with strong affinity for PH, BA, and BSA, respectively, were selected from 16 monomers by using density functional theory (DFT). Molecularly imprinted resin (MIP-4) with tri-functional groups and excellent selectivity for SSA was synthesized using a macroporous polystyrene resin (NDA-1800) as the carrier. In binary systems, MIP-4 exhibited excellent imprinting effect and adsorption selectivity for SSA. X-ray spectroscopy data and DFT calculations illustrated that that the adsorption of SSA on MIP-4 was mainly dependent on the strong electrostatic interaction between the protonated amine group on the resin and -SO3⁻ of SSA, as well as, the hydrogen bond between the neutral amine group and -OH and -COOH of SSA; the order of the three functional groups in identification was -OH > -COOH > -SO3H. In addition, the adsorption performance of MIP-4 was retained after five adsorption–desorption cycles.
Chapter
Vanadium is widely found in nature in various minerals. The weathering of these sources has resulted in its elevated concentration in natural waters in some areas. Vanadium is an important element in industry and its use has also resulted in vanadium-rich effluents. Because of the toxicity of vanadium and its valuable applications, the removal and recovery of vanadium from water streams is crucial. Sorption studies have shown that vanadium removal can be done with a variety of materials. This chapter deals with vanadium(V) sorption from aqueous solutions on different materials and recent achievements in material development.
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With the rapid development of extraction technology of vanadium from black shale, more and more attention has been paid to its mechanism of vanadium separating. Among them, the release and oxidation process of vanadium separating from lattice and the ionic state of vanadium in the solution under the fluorine-containing system need to be revealed urgently to guide and improve the separation and purification of vanadium from black shale. In this study, the migration and coordination of vanadium leaching is preliminarily explored through experiments and simulation studies. Leaching kinetics analysis show that the release of vanadium from black shale is mainly controlled by chemical reaction under the direct acid leaching process. DFT simulations further confirm that the remove of structural oxygen atoms is the control step of vanadium release. Meanwhile, the destruction of V-O octahedron depends on the synergy of H⁺ and F⁻ in turn, which pull vanadium away from mica interfaces in the form of six-coordinated [VF6]. The oxidation process of vanadium is mainly caused by the breaking of V-O bonds and the formation of V-F bonds. After transferring into a fluorine-containing solution, the ionic state of vanadium transforms constantly with the change of the concentration of H⁺ and F⁻, wherein the main reversible coordination process of V(IV) is: VF6²⁻ ⇄ VF5⁻ ⇄ VF4 ⇄ VF3⁺ ⇄ VF3(OH) ⇄ VOF2 ⇄ VOF⁺ ⇄ VO²⁺, and the main reversible coordination process of V(V) is: VF6⁻ ⇄ VF5 ⇄ VF4⁺ ⇄ VF4(OH) ⇄ VOF3 ⇄ VOF2⁺ ⇄ VOF2(OH) ⇄ VO2F ⇄ VO2⁺. Above, the basic theory of vanadium separation from shale at atomic level has been studied systematically.
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Thiourea-modified chitosan-imprinted resin (IM-TUCS) and a corresponding nonimprinted resin (NIM-TUCS) were synthesized and characterized using adsorption experiments. The adsorption results showed that adsorption reached equilibrium within 4 h. The adsorption data were better fitted using the Langmuir model (R² >0.99), and the gold adsorption capacities of IM-TUCS and NIM-TUCS were 933.2 and 373.7 mg·g⁻¹, respectively. The IM-TUCS adsorbent was more suitable for gold than other coexisting anions and cations. The possible mechanism underlying Au(Ⅲ) adsorption on IM-TUCS was further investigated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction analyses. The protonation of the amino group on the resin under low pH conditions promoted Au(Ⅲ) adsorption; O, N and S in the C-OH, C=S and C-NH2 groups contained in the IM-TUCS coordinated with Au(III) ions. The cross-linking of the imprinted resin provided holes that could hold Au(III), thus the imprinted resin supported more Au(III). The adsorption capacity of the IM-TUCS for Au(III) was significantly higher than that of the NIM-TUCS, which is attributed to the cross-linking of the imprinted resin. Moreover, the IM-TUCS showed specific recognition capabilities for Au(III). After elution with the eluent, IM-TUCS was reused for four cycles with a gold recovery rate of approximately 93%, revealing its high potential economic value.
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Black shale-hosted vanadium deposit is an important species of nontraditional mineral resources. The green efficient separation of black shale-hosted vanadium has attracted lots of researchers’ attention. In the paper, two-stage pressurized acid leaching coupled with lixivium recycling was investigated and clarified. Results showed that this coupling technics endowed selective leaching of vanadium under the optimized conditions that were liquid to solid ratio of 1.5 mL/g, leaching time of 120 min, sulfuric acid addition of 12.5 vol%, the first-stage temperature of 180 °C and second-stage temperature of 150 °C. From the first stage to the second stage, the muscovite has been almost dissolved, which guaranteed high vanadium recovery. Through recycling the second-stage lixivium, the first-stage pH value was controlled below pHTθ of Eq.5 (0.27, 180°C) and above pHTθ of Eq.6 (-0.88, 180°C) and Eq.7 (-2.83, 180°C), triggering the isomorphous precipitation of Fe and Al as kalunite-jarosite solid solution. Once fresh sulfuric acid solution touched the first-stage residue, the kalunite-jarosite solid solution can still be stably remained and discharged. The leached Fe and Al ions were directionally gathered to the first stage and precipitated as kalunite-jarosite solid solution. Recent data collected from this coupling technics suggests that the asynchronous dissolution-precipitation of V, Al and Fe was achieved during acid leaching of the black shale.
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In-situ immobilization is a fast soil remediation method that can recover the value of As-contaminated land quickly. Hydrous zirconium oxide was reported for its efficient arsenic adsorption properties in wastewater treatment, but has not been reported in soil remediation with As contamination. Herein, hydrous zirconium oxide modified biochar (BC-Zr) was synthesized along with hydrous ferric oxide modified biochar (BC-Fe) and hydrous titanium oxide modified biochar (BC-Ti). After comparing their As(III)/As(V) adsorption performance under diverse conditions, BC-Zr showed superior As-immobilization potential in both simulated water and real soil leachate environment. To evaluate its performance in soil remediation, pot experiments were conducted in real As-contaminated agricultural soil using cowpea (Vigna unguiculata L.) as an indicator plant. Although all these modified BC could improve the growth of cowpea, the shoot biomass treated by BC-Zr increased by 115.8% than CK, while the As concentration in the stem and leaves decreased by 30.8% and 42.6%, respectively. Interestingly, BC-Zr promoted the root nodule system of cowpea in real As-contaminated soil while BC-Fe and BC-Ti failed. The observation of improved root nodule symbiotic system is significant for further development of soil remediation using in-situ remediation technology. This first successful trial of Zr-based soil amendment indicates the superior As-immobilization property of hydrous zirconium oxide in in-situ remediation of As-contaminated soil, implying the great potential applications of BC-Zr in soil remediation.
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A high concentration of vanadium [V(v)] in groundwater is extremely harmful for humans. Weak movability and low toxicity after microbial V(v) reduction have attracted remarkable attention, especially for using solid carbon sources. However, the influencing factors remain unclear. In this study, the initial V(v) concentration, inocula amount and straw dosage were examined to ascertain the mechanisms behind them. Increasing the initial V(v) concentration led to the decrease of the V(v) removal efficiency, which was also positively correlated with the straw dosage within a certain range. The initial sludge amount was not a main factor affecting microbial V(v) removal in this study. With the initial amount of 10 mg L-1 V(v), 25 mL initial inocula and 5 g straw, 88.2% of V(v) was removed. According to the dissolved organic matter (DOM) analysis results, microbial activity prevailed in groups with higher V(v) removal efficiency, indicating that the V(v) bio-reduction was attributed to the microbial activity, which was considered a major factor. Functional species as unclassified_f_Enterobacteriaceae presumably contributed to the V(v) bioreduction, with upregulated ABC transporter genes and enzymes. This journal is
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In recent years, with the development of economy and industry, water contaminated with heavy metal has become a global environmental problem. Vanadium (V) is an emerging contaminant reported in wastewater along with the increasing mining, smelting and recovering of vanadium ores and application in many fields as a significant national strategy resource. The increasing attention has been paid to the separations of V from water due to its potential toxic to animals and human beings. In the present study, the most common V removal techniques including adsorption, microbiological treatment, chemical precipitation, solvent extraction, electrokinetic remediation, photocatalysis, coagulation and membrane filtration are presented with discussion of their advantages, limitations and the recent achievements. Several major influencing factors and mechanisms of various processes have been briefly analyzed. Some research perspectives are proposed for improving the capacities to remove V from water. The core objective of this review is to provide comprehensive information or database for the superior approach for V removal.
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Severe vanadium pollution in deep soil through surface infiltration during mining activities has been particularly concerned, but little is known about vanadium migration dynamics in vertical soil profile. Indigenous microorganisms widely exist in soil, however, their functions and suffered impacts during vertical vanadium migration have rarely been investigated. In this study, 100 cm height columns were constructed with undisturbed soil around vanadium tailing reservoir were constructed to describe vertical vanadium transport process and corresponding interactions between vanadium and indigenous microorganisms. 91 d continuous leaching with pentavalent vanadium [V(V)] showed that V(V) gradually downward migrated. Soil microorganisms slowed down vertical V(V) migration rate by transferring V(V) to insoluble tetravalent vanadium. Enriched Gemmatimonadaceae and Actinobacteria were identified to contribute to microbial V(V) transformation. Co-existing nitrate weakened the soil’s ability to intercept V(V) via electron competition. Microbial communities were reshaped by vanadium during leaching, while enzyme activities increased slightly due to vanadium stimulation. This work advances the understanding of vertical vanadium migration characteristics in soil, which is essential to risk management and effective remediation of vanadium-polluted sites.
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Due to their numerous effects on human health and the natural environment, water contamination with heavy metals (HMs) and metalloids, caused by their extensive use in various technologies and industrial applications, continues to be a huge ecological issue that needs to be urgently tackled. Additionally, within the circular economy management framework, the recovery and recycling of HMs-based waste as high value-added products (VAPs) is of great interest, owing to their high cost and the continuous depletion of their reserves and natural sources. This paper reviews the state-of-the-art technologies developed for the removal and recovery of HMs from wastewater by providing an in-depth understanding of their remediation mechanisms, while analyzing and critically discussing the recent key advances regarding these treatment methods, their practical implementation and integration, as well as evaluating their advantages and remaining limitations. Herein, various treatment techniques are covered, including adsorption, reduction/oxidation, ion exchange, membrane separation technologies, solvents extraction, chemical precipitation/co-precipitation, coagulation-flocculation, flotation, and bioremediation. A particular emphasis is placed on full recovery of the captured metal pollutants in various reusable forms as metal-based VAPs, mainly as solid precipitates, which is a powerful tool that offers substantial enhancement of the remediation processes’ sustainability and cost-effectiveness. At the end, we have identified some prospective research directions for future work on this topic, while presenting some recommendations that can promote sustainability and economic feasibility of the existing treatment technologies.
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Vanadium and tungsten ion adsorption and desorption characteristics and separation conditions were investigated using a simple porous anion-exchange resin.
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Indigenous microbial consortia are closely associated with soil inherent components including nutrients and minerals. Although indigenous microbial consortia present great prospects for bioremediation of vanadate [V(V)] contaminated soil, influences of some key components, such as available phosphorus (AP), on V(V) biodetoxification are poorly understood. In this study, surface soils sampled from five representative vanadium smelter sites were employed as inocula without pretreatment. V(V) removal efficiency ranged from 81.7 ± 1.4% to 99.5 ± 0.2% in batch experiment, and the maximum V(V) removal rates were positively correlated with AP contents. Long-term V(V) removal was achieved under fluctuant hydrodynamic and hydrochemical conditions in column experiment. Geobacter and Bacillus, which were found in both original soils and bioreactors, catalytically reduced V(V) to insoluble tetravalent vanadium. Phosphate-solubilizing bacterium affiliated to Gemmatimonadaceae were also identified abundantly. Microbial functional characterization indicated the enrichment of phosphate ABC transporter, which could accelerate V(V) transfer into intercellular space for efficient reduction due to the structural similarity of V(V) and phosphate. This study reveals the critical role of AP in microbial V(V) decontamination and provides promising strategy for in situ bioremediation of V(V) polluted soil.
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Vanadium mining activities can cause contamination of the surrounding geological environment. Vanadium may exist in multiple matrices due to its migration and transformation, forming interactive relationships; however, the connection between vanadium distributions in multiple matrices and microbial community responses remains largely unknown. Vanadium is a redox-sensitive metal that can be microbiologically reduced and immobilized. To date, bioremediation of vanadium-contaminated environments by indigenous microorganisms has rarely been evaluated. This paper reports a systematic investigation into vanadium distributions and microbial communities in soils, water, and sediment from Panzhihua, China. Large vanadium contents of 1130.1 ± 9.8 mg/kg and 0.13 ± 0.02 mg/L were found in surface soil and groundwater. Vanadium in surface water tended to precipitate. Microbial communities isolated from similar environments were alike due to similarity in matrix chemistry whereas communities were distinct when compared to different matrices, with lower richness and diversity in groundwater. Proteobacteria was distributed widely and dominated microbial communities within groundwater. Redundancy analysis shows that vanadium and nutrients significantly affected metal-tolerant bacteria. Long-term cultivation (240 days) suggests the possibility of vanadium bioremediation by indigenous microorganisms, within acid-soluble fraction. This active fraction can potentially release mobile vanadium with shifted redox conditions. Vanadium (V) was bio-reduced to less toxic, mobile vanadium (IV) primarily by enriched Bacillus and Thauera. This study reveals the biogeochemical fate of vanadium in regional geological environments and suggests a bioremediation pathway via native vanadium-reducing microbes.
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Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value qmax) was 27 mg V g−1 resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L−1 V through the column. When eluting the column 57–72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs.
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A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with <1% of the total vanadium readily mobilised. Column experiments revealed that only <0.1% of vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20μgL(-1) to 50-90μgL(-1), indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils.
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Here we fabricated a novel nanocomposite HZO-201, an encapsulated nanosized hydrous zirconium oxide (HZO) within a commercial porous polystyrene anion exchanger D201, for highly efficient defluoridation of water. HZO-201 exhibited much higher preference than activated alumina and D201 toward fluoride removal when competing anions (chloride, sulfate, nitrate, and bicarbonate) coexisted at relatively high levels. Fixed column adsorption indicated that the effective treatable volume of water with HZO-201 was about 7-14 times as much as with D201 irrespective of whether synthetic solution or groundwater was the feeding solution. In addition, HZO-201 could treat >3000 BV of the acidic effluent (around 3.5 mg F(-)/L) per run at pH 3.5, compared to only ∼4 BV with D201. The exhausted HZO-201 could be regenerated by NaOH solution for repeated use without any significant capacity loss. Such attractive performance of HZO-201 resulted from its specific hybrid structure, that is, the host anion exchanger D201 favors the preconcentration of fluoride ions inside the polymer based on the Donnan principle, and the encapsulated nanosized HZO exhibits preferable sequestration of fluoride through specific interaction, as further demonstrated by XPS spectra. The influence of solution pH, competitive anions, and contact time was also examined. The results suggested that HZO-201 has a great potential in efficient defluoridation of groundwater and acidic mine drainage.
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The defluoridation performance and adsorption mechanism of a high capacity hydrous zirconium oxide adsorbent were investigated. Fluoride adsorption on the hydrous zirconium follows a pseudo-second-order pattern. Maximum adsorption capacities of 124 and 68 mg-F−/g-adsorbent were obtained in batch studies at pH 4 and 7, respectively. The adsorption capacity showed a continuously increasing trend with decreasing pH. The hydrous zirconium oxide is superior to most Zr-containing adsorbents. Surface titration and zeta potential measurements defined this adsorbent’s surface charging behavior and proved electrostatic interactions existed between fluoride and surface charge of the hydrous zirconium oxide. Raman, FTIR and 19F solid-state NMR observations definitively confirmed that fluoride was adsorbed by chemical reactions which formed Zr–F bonds on the hydrous zirconium oxide. XPS analyses indicated that a seven-coordinate polyhedral zirconium oxyfluoride species, ZrO2F5, and possibly some ZrO3F4 formed on the adsorbent’s surface by exchange reactions between surface hydroxyl groups with fluoride. Based on Zr-oxyfluoride species analyses by XPS, fluoride adsorption reactions on the hydrous zirconium oxide were suggested, including both associative and dissociative mechanistic pathways for fluoride uptake. This hydrous zirconium oxide adsorbent is a promising modestly priced adsorbent for practical application and its fluoride adsorption mechanisms are now better understood.
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Aquifer co-contamination by vanadium (V) and pentachlorophenol (PCP) involves complicated biogeochemical processes that remain poorly understood, particularly from the perspective of microbial metabolism. Batch experiment results demonstrated that V(V) and PCP could be competitively bio-reduced, with 96.0 ± 1.8% of V(V) and 43.4 ± 4.6% of PCP removed during 7 d operation. V(V) was bio-transformed to vanadium (IV), which could precipitate naturally under circumneutral conditions, facilitating the removal of up to 78.2 ± 3.1% dissolved total V. The PCP reductive dechlorination products were mainly 2,4,6-trichlorophenol and 4-monochlorophenol with lower toxicity. High-throughput 16S rRNA gene sequencing indicated that Pseudomonas, Soehngenia, and Anaerolinea might be responsible for the two bio-transformations, with detected functional genes of nirS and cprA. Extracellular reduction by cytochrome c and intracellular conversion by nicotinamide adenine dinucleotide (NADH) occurred for both V(V) and PCP. Extracellular proteins in microbial-secreted extracellular polymeric substances (EPS) might also be involved in these enzymatic bioprocesses. EPS could protect microbial cells through V(V) binding by the chemically reactive carboxyl (COO⁻), and hydroxyl (–OH) groups. These findings elucidate the metabolic processes during anaerobic V(V) and PCP biotransformation, advance understanding of their biogeochemical fates, and provide a foundation on which to develop novel strategies for remediation of co-contaminated aquifers.
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The coexistence of arsenic (As) and fluoride (F) in drinking water is an urgent environmental issue that causes increasing public concerns. The need for effective simultaneous removal of As and F has motived great research efforts. Herein, a novel {201}TiO2-ZrO2 composite was synthesized and its application mechanism was explored. Batch adsorption experiments show that the As(III), As(V), and F adsorption followed the pseudo-second-order kinetics with the Langmuir adsorption capacity at 58.5, 21.6, and 13.1 mg/g, respectively. EXAFS and in situ ATR-FTIR results suggested that TiO2 surface sites were occupied by As(III) and As(V) in bidentate binuclear structures, and ZrO2 sites preferentially adsorbed As(III) and F in monodentate mononuclear configurations. This molecular structure obtained in the mono-adsorption system was integrated with the charge distribution multisite surface complexation model to accurately predict the As and F co-existing adsorption behaviors. The results in competitive adsorption, regeneration, and application evidenced that the {201}TiO2-ZrO2 composite is a promising adsorbent for simultaneous As and F removal.
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In this work, Mg(OH)2 was incorporated into ZrO2 to obtain a novel Mg(OH)2/ZrO2 composite (MZ) by a simple co-precipitation method for phosphate adsorption. For comparison purpose, pure ZrO2 and Mg(OH)2 were also fabricated. The as-prepared MZ, ZrO2 and Mg(OH)2 were characterized by SEM, EDS, N2 adsorption/desorption and pHPZC, and their phosphate adsorption properties were comparatively investigated in batch mode. The MZ samples before and after phosphate adsorption were characterized by XPS, and the phosphate-adsorbed MZ was characterized by ³¹P NMR. The results showed that MZ was mainly composed of ZrO2 and Mg(OH)2. In addition, MZ had a larger specific surface area than single-component ZrO2 and Mg(OH)2. MZ exhibited a much higher affinity towards phosphate in aqueous solution than pure ZrO2 and Mg(OH)2. The Langmuir maximum phosphate adsorption capacity of MZ was 87.2 mg PO4/g at initial pH 7, which was 84% and 4.3 times higher than those of single-component ZrO2 and Mg(OH)2, respectively. Phosphate was adsorbed onto the MZ surface mainly via a ligand exchange between the ZrO2 phase and phosphate forming inner-sphere phosphate complexes as well as the reaction between the Mg(OH)2 phase and phosphate forming Mg-P compounds such as MgHPO4 and Mg3(PO4)2. The enhanced phosphate adsorption by the incorporation of Mg(OH)2 into ZrO2 could be attributed to: (i) the increase in the specific surface area of the adsorbent material; and (ii) the enhanced adsorption of phosphate on the ZrO2 component by the presence of Mg²⁺ that was dissolved from the Mg(OH)2 component. Results of this work indicate that MZ is a more promising adsorbent for the removal of phosphate from wastewater than Mg(OH)2 and ZrO2.
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Groundwater co-contaminated by vanadium (V) (V(V)) and nitrate requires efficient remediation to prevent adverse environmental impacts. However, little is known about simultaneous bio-reductions of V(V) and nitrate supported by gaseous electron donors in aquifers. This study is among the first to examine microbial V(V) reduction and denitrification with hydrogen as the sole electron donor. V(V) removal efficiency of 91.0 ± 3.2% was achieved in test bioreactors within 7 d, with synchronous, complete removal of nitrate. V(V) was reduced to V(IV), which precipitated naturally under near-neutral conditions , and nitrate tended to be converted to nitrogen, both of which processes helped to purify the groundwater. Volatile fatty acids (VFAs) were produced from hydrogen oxidation. High-throughput 16S rRNA gene sequencing and metagenomic analyses revealed the evolutionary behavior of microbial communities and functional genes. The genera Dechloromonas and Hydrogenophaga promoted bio-reductions of V(V) and nitrate directly coupled to hydrogen oxidation. Enriched Geobacter and de-nitrifiers also indicated synergistic mechanism, with VFAs acting as organic carbon sources for hetero-trophically functional bacteria while reducing V(V) and nitrate. These findings are likely to be useful in revealing biogeochemical fates of V(V) and nitrate in aquifer and developing technology for removing them simultaneously from groundwater.
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Resin D201, D314 and 717 were compared for their efficiency to extract vanadium from hydrochloric acid leaching solution of red mud. The adsorption parameters were investigated in details by using the three resins. The separation characteristics and mechanism of vanadium were analyzed with infrared spectroscopy and adsorption kinetics. More than 99% of vanadium was selectively adsorbed by using resin D201 at pH value of 2.0, flow speed of 6 m³/h·m³ resin, resin D314 at pH value of 3.0, flow speed of 4.8 m³/h·m³ resin, and resin 717 at pH value of 5.0, flow speed of 7.92 m³/h·m³ resin, respectively. The maximum loading of vanadium by using resin D201 was more than resin 717 and D314. The vibration peak of functional group on the resins increased after adsorption of vanadium from the leaching solution. The adsorption process of vanadium was according with the pseudo-second adsorption kinetic model.
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Vanadium(V) is an emerging contaminant in the most recent EPA’s candidate contaminant list (CCL4). The redox chemistry of vanadium controls its occurrence in the aquatic environment, but the impact of vanadium(V) speciation on its redox properties remains largely unknown. This study developed electrochemical techniques with a rotating ring disk electrode to examine the reduction kinetics of four pH-dependent vanadium(V) species in the presence and absence of phosphate. Results showed that the reduction of VO2+, HxV4O12+x(4+x)- (V4) and HVO42- proceeded via a one-electron transfer, while the reduction of NaxHyV10O28(6-x-y)- (V10) underwent a two-electron transfer process. Koutecky-Levich and Tafel analyses showed that the intrinsic reduction rate constants followed the order of V10 > VO2+ > V4 > HVO42-. Ring electrode collection efficiency indicated that the reduction product of V10 was stable, while those of VO2+, HVO42- and V4 were short lived with half-lives between milliseconds and seconds. With molar ratios of phosphate to vanadium(V) varying from 0 to 1, the presence of phosphate accelerated the reduction kinetics of V10 and V4, and enhanced the stability of the reduction products of VO2+, V4 and HVO42-. This study suggests that phosphate complexation significantly impacts the efficiency of reductive vanadium(V) removal in water treatment.
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Vanadium (V) pollution in groundwater has posed serious risks to the environment and public health. Anaerobic microbial reduction can achieve efficient and cost-effective remediation of V(V) pollution, but its interactions with coexisting common electron acceptors such as NO3(-), Fe(3+), SO4(2-) and CO2 in groundwater remain unknown. In this study, the interactions between V(V) reduction and reduction of common electron acceptors were examined with revealing relevant microbial community and identifying dominant species. The results showed that the presence of NO3(-) slowed down the removal of V(V) in the early stage of the reaction but eventually led to a similar reduction efficiency (90.0% ± 0.4% in 72-h operation) to that in the reactor without NO3(-). The addition of Fe(3+), SO4(2-), or CO2 decreased the efficiency of V(V) reduction. Furthermore, the microbial reduction of these coexisting electron acceptors was also adversely affected by the presence of V(V). The addition of V(V) as well as the extra dose of Fe(3+), SO4(2-) and CO2 decreased microbial diversity and evenness, whereas the reactor supplied with NO3(-) showed the increased diversity. High-throughput 16S rRNA gene pyrosequencing analysis indicated the accumulation of Geobacter, Longilinea, Syntrophobacter, Spirochaeta and Anaerolinea, which might be responsible for the reduction of multiple electron acceptors. The findings of this study have demonstrated the feasibility of anaerobic bioremediation of V(V) and the possible influence of coexisting electron acceptors commonly found in groundwater.
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Natural water with a high specific ultraviolet absorbance (SUVA) value (4.3) and high vanadium concentration (1.2–1.9 mg/l) was investigated for vanadium(V) removal through sorption using solid sorbents and co-precipitation with a ferric sulphate coagulant. Although there are studies on vanadium removal by sorption and co-precipitation, the removal of vanadium in the presence of natural organic matter has not been adequately addressed. In the sorption method, hexadecyltrimethylammonium bromide (HDTMA) modified clinoptilolite (Cp) and synthetic zeolite (Na-P1), and ferric oxyhydroxide (CFH-12) were tested as sorbents. In the co-precipitation method, vanadium removal may occur simultaneously with the coagulation process of humic substances. Co-precipitation with iron was proven to be more efficient than sorbent-based processes. A ferric sulphate coagulant dosage (as product) of 75 mg/l resulted in a residual vanadium concentration of 70–80 μg/l and vanadium removal closely followed the removal of humic substances. This might be related to the binding of vanadium by the humic substances. Regarding sorbents, 1–2 g/l dosages of Na-P1 (at pH ∼6) and CFH-12 (pH 3.7–4.7) were required to reach a low vanadium concentration. A much higher dosage was required for Cp, which can be explained by the lower loading of HDTMA on the zeolite surface. Na-P1 increased the pH of the treated water whereas CFH-12 decreased the pH. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the pH change was due to the leaching of hydroxides and calcite from the Na-P1 and jarosite from the CFH-12. The organo-zeolites exhibited fast kinetics. The surface binding of vanadium and vanadium-humic substances can be regarded as the main mechanism. For CFH-12, the diffusion of vanadium into pores was a significant, albeit slow mechanism, in addition to the sorption on the external surface. The humic substances present in natural water significantly affected the mechanism of vanadium uptake. The XPS data confirmed the strong binding of organic matter on CFH-12 whereas organic matter was only weakly bound to the organo-zeolites.
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A novel resource utilization of the calcium-based semi-dry flue gas desulfurization ash is investigated. In the present study, the semi-dry desulfurization ash is used as a reductant for chromium and vanadium removal by chemical reduction precipitation, the byproduct gypsum and chromium-contained sludge are obtained. Besides, the effects of main operational parameters (reaction pH, desulfurization ash dosage and reaction time) on the heavy metal removal are investigated, and the main reaction mechanism for this treatment technology is also proposed. Under the optimal conditions, the residual concentrations of Cr(VI), total Cr and V are 0.163mg/L, 0.395mg/L and 0.155mg/L, respectively. Additionally, byproduct gypsum and chromium-contained sludge are characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and thermogravimetry differential scanning calorimetry (TG-DSC), respectively. Finally, the resource utilization methods of the byproduct gypsum and chromium-contained sludge from this technology are also submitted. The byproduct gypsum can be utilized to produce hemihydrate calcium sulfate whisker, and the roasted heavy metal precipitation can be used as a primary chromium raw material (Cr2O3 content is about 83%).
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Spatial distribution of vanadium in surface soils from different processing stages of vanadium-bearing titanomagnetite in Panzhihua mining and smelting area (China) as well as responses of microbial communities including bacteria and fungi to vanadium were investigated by fieldwork and laboratory incubation experiment. The vanadium contents in this region ranged from 149.3 to 4793.6 mg kg(-1), exceeding the soil background value of vanadium in China (82 mg kg(-1)) largely. High-throughput DNA sequencing results showed bacterial communities from different manufacturing locations were quite diverse, but Bacteroidetes and Proteobacteria were abundant in all samples. The contents of organic matter, available P, available S and vanadium had great influences on the structures of bacterial communities in soils. Bacterial communities converged to similar structure after long-term (240 d) cultivation with vanadium containing medium, dominating by bacteria which can tolerate or reduce toxicities of heavy metals. Fungal diversities decreased after cultivation, but Ascomycota and Ciliophora were still the most abundant phyla as in the original soil samples. Results in this study emphasize the urgency of investigating vanadium contaminations in soils and provide valuable information on how vanadium contamination influences bacterial and fungal communities.
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In this work, we report a feasible approach to synthesize a ternary nanocomposites, Pt/lanthanum doped mesoporous zirconium oxide (Pt/La2O3-ZrO2), via an effective two-step method. Ordered mesoporous La2O3-ZrO2 composites were firstly fabricated with mesoporous silica KIT-6 as a hard template. Subsequently, uniform Pt nanoparticles encapsulated by 4 hydroxyl-terminated poly (amidoamine) (G4-OH PAMAM) dendrimers were deposited on the La2O3-ZrO2 composites. The as-prepared samples were characterized by transmission electron microscope (TEM), N2 adsorption–desorption isotherm analysis, energy dispersion X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (H2-TPR). The average size of PtDENs was found to be 1.48nm in diameter. Furthermore, the introduction of La could improve the structure of the supports which was confirmed by XRD and H2-TPR analysis. The reduction of p-nitrophenol to p-aminophenol by NaBH4 was utilized to evaluate the catalytic performances of catalysts. Results indicated that the Pt/La2O3-ZrO2 catalyst calcined in nitrogen at 550°C exhibited the highest catalytic performance and still kept the high catalytic activity even after six cycles. This phenomenon suggests that synergistic effect among Pt-Zr-La could enhance the catalytic efficiency. Finally, reaction mechanism was proposed for the reduction of p-nitrophenol.
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A novel treatment for chromium, vanadium and ammonium from vanadium industrial wastewater using a byproduct of magnesium-based wet flue gas desulfurization is investigated. In the present study, the byproduct is used as a reductant for chromium and vanadium removal by chemical precipitation, and the residual magnesium ion can also be used to remove ammonium in the present of phosphate by struvite crystallization. Besides, the effects of main operational parameters (reaction pH, byproduct dosage and reaction time) on the heavy metal removal and ammonium removal (reaction pH, Mg²⁺:NH4⁺:PO4³⁻ molar ratio and reaction time) are investigated, and the reaction mechanism for this treatment technology is also proposed. Under the optimal conditions, the residual concentrations of chromium(IV), total chromium and vanadium are 0.046 mg/L, 0.468 mg/L and 0.06 mg/L, respectively. The removal efficiency of ammonium is 95.72% and the residual concentrations of ammonium and phosphorus are 137.12 mg/L and 5.49 mg/L, respectively. Additionally, the precipitations are characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and thermogravimetry differential scanning calorimetry (TG-DSC), respectively. Finally, a resource utilization method of the precipitation sludge from this technology is also presented.
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D201 resin and P507 extractant diluted with sulfonated kerosene were used to respectively separate vanadium and scandium, and impurity ions from hydrochloric acid leaching solution of red mud. More than 99% of vanadium was selectively adsorbed from the hydrochloric acid leaching solution under the conditions of pH value of 1.8, volume ratio of leaching solution to resin of 10, and flow rate of 3.33 mL/min. Maximum extraction and separation of scandium was observed from the acid leaching solution at an aqueous pH value of 0.2. More than 99% of scandium can be selectively extracted using 15% P507, 5% TBP at the aqueous solution/organic phase (A/O) ratio of 10:1 for 6 min. The loaded organic phase was washed with 0.3 mol/L sulfuric acid, wherein most impurities were removed. After the process of desorption or stripping, precipitation, and roasting, high-purity V2O5 and Sc2O3 were obtained. Finally, a conceptual flow sheet was established to separate and recover vanadium and scandium from red mud hydrochloric acid leaching solution.
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Various organic acids in wastewater effluent could significantly influence the performance of phosphate adsorbent. This study focused on the effects of organic acids of different-molecular-size on phosphate adsorption by a novel nanocomposite HZO-201. Three organic acids (gallic acid (GA), tannic acid (TA) and humic acid (HA)) with distinct molecular size (HA > TA > GA) were chosen for this purpose. Both isotherm and kinetic tests of phosphate adsorption were conducted in the single-phosphate and binary system, and a series of microscopic techniques (i.e., XPS, FT-IR and SEM-EDX) and N2 adsorption-desorption test were employed to explore the underlying mechanism. It was found that GA could greatly weaken phosphate adsorption capability of HZO-201 by directly competing for ammonium group on the nanocomposite, TA exhibited significant inhibition on phosphate adsorption rate mainly through pore constriction/blockage, while HA posed negligible impact on phosphate adsorption because of the size exclusion effect. It was also observed that although GA, TA and HA showed substantial influence on bulky HZO due to complexation, their impact on the nano-HZO loaded inside HZO-201 was little. The covalently bounded ammonium group and the networking pore structure of HZO-201 may play important roles in it.
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Mg/Al ratio plays a significant role for anion adsorption by Mg/Al-layered double hydroxides (Mg/Al-LDHs) modified biochar. In this study, Mg/Al-LDHs biochar with different Mg/Al ratios (2, 3, 4) were prepared by co-precipitation for phosphate removal from aqueous solution. Factors on phosphate adsorption including Mg/Al ratio, pH, and the presence of other inorganic anions were investigated through batch experiments. Increasing Mg/Al ratio in the Mg/Al-LDHs biochar composites generally enhanced phosphate adsorption with Langmuir adsorption maximum calculated at 81.83mg phosphorous (P) per gram of 4:1Mg/Al-LDHs biochar at pH3.0. The adsorption process was best described by the pseudo-second-order kinetic model. Solution pH had greater effects on the phosphate adsorption by Mg/Al LDHs biochar composites with lower Mg/Al ratios. The presence of other inorganic anions decreased the phosphate adsorption efficiency in the order of F(-) > SO4(2-) > NO2(-) >Cl(-). Phosphate adsorption mechanism involves ion exchange, electrostatic attraction and surface inner-sphere complex formation. Overall, Mg/Al-LDHs biochar composites offer a potential alternative of carbon-based adsorbent for phosphate removal from aqueous solution.
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Vanadium (V) and chromium (Cr) co-exist in the whole process of V extraction from the vanadium titano-magnetite ore in China. It remains a challenge to remove trace V(V) from Cr(VI) in a simple way. Based on facile pretreatment of transforming Cr(VI) selectively, a novel method to remove V(V) from Cr(VI) by anion exchange resin Dex-V has been established. The influence of operation parameters including pH, contact time and temperature on adsorption ratio has been investigated. The Langmuir model and Henry model were successfully applied to describe the adsorption behavior of V by the Dex-V resin. It is shown that V is adsorbed chemically in monolayer and the Dex-V resin presents a homogeneous nature. Kinetics of V adsorption was analyzed with the pseudo-second order model, the Richenberg model and the Weber–Morris model. Results show that the rate of V adsorption is controlled by film diffusion in initial 70 min and the intra-particle diffusion contributes to the rate-controlling after 70 min. The proposed method was applied to remove V from real waste water and the removal ratio as high as 96% was obtained, with Cr recovery of 95%, which validates the effectiveness and efficiency of the novel method. This work has thus provided new insights into separation and recovery of analog metals in aqueous.
Article
Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.
Article
In this present study, a new chitosan bead modified with titanium ions (TiCB) was prepared and employed for the adsorption of vanadium ions from aqueous solutions. Batch adsorption experiments were performed to research the effect of various factors, including pH, temperature, contact time and initial concentration of vanadium(V) ions. The adsorption of vanadium was followed by the pseudo second-order kinetic and the Langmuir isotherm model, with a remarkable maximum adsorption capacity of 210mg/g. The analysis of thermodynamic parameters (△G(o), △H(o) and △S(o)) revealed that the nature of adsorption was feasible, spontaneous (△G(o) <0) and endothermic (△H(o) >0) process. FTIR, EDS, EMI and XPS studies suggested that the mechanisms of adsorption were possibly attributed to electrostatic attraction, ligand-exchange and redox reaction between TiCB and vanadium ions. Copyright © 2015. Published by Elsevier B.V.
Article
Bioelectricity generated from the microbial fuel cell (MFC) is applied to the bioelectrical reactor (BER) directly to enhance microbial reduction of vanadium (V) (V(V)) in groundwater. With the maximum power density of 543.4 mW m−2 from the MFC, V(V) removal is accelerated with efficiency of 93.6% during 12 h operation. Higher applied voltage can facilitate this process. V(V) removals decrease with the increase of initial V(V) concentration, while extra addition of chemical oxygen demand (COD) has little effect on performance improvement. Microbial V(V) reduction is enhanced and then suppressed with the increase of conductivity. High-throughput 16S rRNA gene pyrosequencing analysis implies the accumulated Enterobacter and Lactococcus reduce V(V) with products from fermentative microorganisms such as Macellibacteroides. The presentation of electrochemically active bacteria as Enterobacter promotes electron transfers. This study indicates that application of bioelectricity from MFCs is a promising strategy to improve the efficiency of in-situ bioremediation of V(V) polluted groundwater.
Article
In the present paper, zirconium immobilized cross-linked chitosan (Zr-CCS) was reported for the adsorption of fluoride. Zr-CCS was synthesized by methods of membrane- forming and subsequent cross-linking reaction. Zr-CCS was characterized by FT-IR, XRD, and SEM technologies. Batch adsorption experiments were performed to evaluate the adsorption capacity of Zr-CCS towards fluoride. The adsorption of fluoride onto the Zr-CCS favored at low pH values, and reduced in the presence of other co-anions. The adsorption equilibrium data had a good agreement with the Langmuir isotherm model, and the maximum adsorption capacity was calculated as 48.26mg/g for fluoride at 303K and natural pH (6.0). Thermodynamic parameters indicate that the nature of fluoride adsorption was spontaneous and endothermic. The adsorption mechanism of fluoride onto the Zr-CCS was controlled by chemical ion-exchange and electrostatic attraction between Zr-CCS and fluoride. Copyright © 2015. Published by Elsevier B.V.
Article
This study was investigated for the trace phosphate removal at high feed flow rate by ligand exchange fibrous adsorbent. The zirconium(IV) loaded bifunctional fibers containing both phosphonate and sulfonate were used as a highly selective ligand exchange adsorbent for trace phosphate removal fromwater. The precursory fiber of the bifunctional fibers was co-grafted by polymerization of chloromethylstyrene and styrene onto polyethylene coated polypropylene fiber and then bifunctional fibers were prepared by Arbusov reaction followed by phosphorylation and sulfonation. Phosphate adsorption experimental work was carried out in column approach. Phosphate adsorption increased with decreasing the pH of feed solutions. An increase in the feeds flow rate brings a decrease in both breakthrough capacity and total adsorption. The effect of competing anions on phosphate adsorption systems was investigated. The experimental findings reveal that the phosphate adsorption was not affected in the presence of competing anions such as chloride and sulfate despite the enhancement of the breakthrough points and total adsorption. Due to high selectivity to phosphate species, low concentration level of phosphate (0.22 mg/L) was removed at high feed flow rate of 450 h�1 in space velocity. The adsorbed phosphate on the Zr(IV) loaded fibrous column was quantitatively eluted with 0.1 M NaOH solution and then the column was regenerated by 0.5 M H2SO4 for the next adsorption operation. During many adsorptioneelutioneregeneration cycles, no measurable Zr(IV) was found in the column effluents. Therefore, the Zr(IV) loaded bifunctional fibrous adsorbent is to be an effective means to treat wastewater to prevent eutrophication in the receiving water bodies for long time without any deterioration.
Article
Hydrous zirconium oxide (HZO)-originated nanocomposite adsorbent of excellent stability against pH variation and organic ligands was fabricated for efficient arsenic removal from water. The nanocomposite adsorbent HZO-201 was obtained by encapsulating nanosized HZO particles inside a polystyrene anion exchanger D201. Negligible metal dissolution was observed from HZO-201 in solution of acidic pHs (to similar to 1) and oxalate at high levels, while significant metal leaching occurred from a similar hydrated ferric oxide-based nanocomposite HFO-201of the same host. Arsenate adsorption by HZO-201 is a pH-dependent process with maximum capacity of 88.74 mg/g at pH 7.0 +/- 0.1, comparable to HFO-201 under similar conditions. As compared to sulfate, chloride, and bicarbonate, silicate and phosphate could inhibit arsenic uptake more strongly by HZO-201. Fixed-bed adsorption indicated that arsenate in simulated groundwater could be effectively captured from 100 gg/L to <10 mu g/L within 2600 BV (bed volume), and that in a real acidic mining effluent could be removed from 750 mu g/L to <50 mu g/L within 2900 By. The exhausted HZO-201 was also amenable to efficient regeneration with a binary NaCI-NaOH solution for repeated use without any significant capacity loss.
Article
In this present study, an inorganic-biopolymer composite based on chitosan-zirconium(IV) was prepared and investigated as a biosorbent for the removal of vanadium(V) ions from aqueous solution. The resulting composite before and after adsorbed V(V) were characterized by using FT-IR, XRD, SEM and EDS, respectively. Various relevant parameters affecting the adsorption capacity such as pH, initial concentration, contact time, temperature and co-existing ions were evaluated. The results demonstrated that the optimum pH was found to be 4.0 and the equilibrium was achieved after 4h for V(V) adsorption. The Langmuir isotherm model could be well described the adsorption of V(V), with the maximum adsorption capacity of 208mgg(-1) at 30°C. The kinetics data were well fitted to pseudo-second-order equation, indicating that chemical sorption as the rate-limiting step of adsorption mechanism. The calculated thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated that the adsorption process was feasible, spontaneous and endothermic in nature. Moreover, co-existing ions including nitrate, chloride and sulfate had a certain effect on the uptake of V(V). The V(V) loaded chitosan-zirconium(IV) composite could be regenerated by 0.01molL(-1) sodium hydroxide, with efficiency greater than 95%.
Article
For highly efficient removal of Cr(VI) from aqueous solutions, amino-functionalized titanate nanotubes (NH2-TNTs) with excellent adsorption performance have been synthesized by covalently grafting [1-(2-amino-ethyl)-3-aminopropyl]trimethoxysilane (AAPTS) onto protonated titanate nanotubes (HTNTs) with great amounts of surface hydroxyl groups. TEM and XRD results confirmed that the nanotubular morphology and crystal structure of HTNTs and NH2-TNTs were preserved. FTIR spectra demonstrated that AAPTS was covalently bonded on the surface of HTNTs. Batch adsorption experiments showed that pseudo-second-order kinetics model and Langmuir isotherm model fitted the adsorption data very well for both materials, and the Cr(VI) adsorption capacity on NH2-TNTs calculated by Langmuir model was up to 153.85 mg g−1 at initial pH 5.4 and 30 °C, much larger than that on HTNTs (26.60 mg g−1). Moreover, uptake of Cr(VI) ions onto NH2-TNTs could be completed within only 5 min for 95% adsorption of the maximum. Influence of different species of Cr(VI) under varying pH was also considered. FTIR and XPS analysis indicated that Cr(VI) ions were first exchanged with NO3- linked on the positively charged amino groups and then partially reduced to Cr(III). Afterwards, Cr(III) were then totally chelated with amino groups and no Cr(III) was detected in the solution after Cr(VI) adsorption at pH range of 1–12.
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Vanadium (V) and chromium (VI) are the main metals found in vanadium containing wastewater with large amount and great toxicity. In present study, reduction of V(V) and Cr(VI) together with electricity generation is successfully achieved in double chamber microbial fuel cells (MFCs) by employing vanadium containing wastewater as the cathodic electron acceptor. The V(V) and Cr(VI) reduction efficiencies for 240 h operation approach up to 67.9 ± 3.1% and 75.4 ± 1.9%, respectively, with a maximum power density of 970.2 ± 20.6 mW m−2. The power output is enhanced, compared with the results from MFCs with V(V) as the sole electron acceptor, while the decrease of the cathode efficiency caused by deposits from Cr(VI) reduction process can also be mitigated. After reduction, chromium is mainly deposited on the cathode surface in the form of Cr(III), while most of vanadium can be precipitated from the exhausted catholyte by adjusting pH, thus treating vanadium containing wastewater successfully with energy harvest based on MFC technology. The operating principles of MFCs with two different electron acceptors are also reported for the first time.
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Leaching of roasted stone coal with sulfuric acid results in a mixed vanadium solution containing Fe(III), Fe(II), Al(III) and Mg(II). Separation of V from synthetic sulfate solution containing these impurities has been investigated by ion exchange and solvent extraction. In ion exchange experiments, anion exchange resin ZGA414 was tested as its optimum adsorption capacity compared with D202, D453, D301FC and ZGA351 resins, and D2EHPA and TBP diluted with kerosene were employed in solvent extraction. Ion exchange tests indicated that only V(V) was loaded from the synthetic solution at pH > 1.5, while it was difficult to separate V(V) from Fe(III), which also made resin toxic. Solvent extraction experiments revealed that V(IV) had a better extraction ratio than that of V(V), while Fe(III) had a serious effect on the extraction of V(IV). The co-extraction ratio of Al(III) and Mg(II) can be decreased by controlling their concentrations lower than 10 g/L. Counter-current experiments with D2EHPA presented that 99% of V(IV) was extracted from the real leach solution after reduction process, leaving most of Fe(II), Al(III) and Mg(II) in the raffinate.
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The species of vanadium extracted by a weak base anion resin D314 from sulphuric acid leach solution of stone coal was investigated. The saturated adsorption capacity of vanadium on the resin was found to be up to 501mg/mL wet resin with a distribution ratio of 950 at pH=3–4 and 15°C using static adsorption method. Vanadium was adsorbed in the form of V10O286− and HV10O285−. The study provides the theory and fundamental basis for the industrial application of weak base resins for extraction of vanadium from acid leach solution of stone coal.
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The metal anions of vanadium (V) and chromium (VI) in aqueous solution can be effectively adsorbed by Zr(IV)-impregnated collagen fiber (ZrICF). The maximum adsorption capacity of V(V) takes place within the pH range of 5.0 to8.0, while that of Cr(VI) is within the pH range of 6.0 to 9.0. When the initial concentration of metal ions was 2.00mmol L−1 and the temperature was 303K, the adsorption capacity of V(V) on Zr-ICF was 1.92mmol g−1 at pH5.0, and the adsorption capacity of Cr(VI) was 0.53mmol g−1 at pH7.0. As temperature increased, the adsorption capacity of V(V) increased, while that of Cr(VI) was almost unchanged. The adsorption isotherms of the anionic species of V(V) and Cr(VI) can be fit by the Langmuir equation. The adsorption rate of V(V) follows the pseudo-first-order rate model, while the adsorption rate of Cr(VI) follows the pseudo-second-order rate model. Furthermore, ZrICF shows high adsorption selectivity to V(V) in the mixture solution of V(V) and Cr(VI). Practical applications of ZrICF could be expected in consideration of its performance in adsorption of V(V) and Cr(VI).
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Activated carbon fibers (ACFs) were used for the adsorption of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (DNP) from aqueous solutions, and the adsorption capacities followed the order of TCP > DNP ≈ DCP > 4-NP > 4-CP > 2-CP > phenol. Adsorption isotherms at different temperatures were determined and modeled with Langmuir, Freundlich and Redlich–Peterson equations. Thermodynamic parameters were calculated and correlated with the adsorption behaviors. The effects of solution pH on the adsorption were also studied. The adsorption mechanism was discussed based on the experimental results, and the π–π interactions, solvent effects, hydrophobic interactions and molecular dimensions were considered to be important in the adsorption. Kinetic studies showed rapid adsorption kinetics of the phenols, due to the open pore structure of the ACFs. The kinetics was fitted with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Steric effects on adsorption kinetics were observed for TCP, 4-NP and DNP, but serious impact on the ultimate uptake was only found for DNP. The relationship between the steric effects and the molecular dimension was also proposed.
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A simple and facile preconcentration procedure based on the coprecipitation of trace heavy metal ions with copper(II)-rubeanic acid complex has been developed. The analytical parameters including pH, amounts of rubeanic acid, sample volume, etc. was investigated for the quantitative recoveries of Pb(II), Fe(III), Cd(II), Au(III), Pd(II) and Ni(II). No interferic effects were observed from the concomitant ions. The detection limits for analyte ions by 3 sigma were in the range of 0.14 microg/l for iron-3.4 microg/l for lead. The proposed coprecipitation method was successfully applied to water samples from Palas Lake-Kayseri, soil and sediment samples from Kayseri and Yozgat-Turkey.
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Vanadium is listed on the United States Environment Protection Agency (USEPA) candidate contaminant list # 2 (CCL2), and regulatory guidelines for vanadium exist in some US states. The USEPA requires treatability studies before making regulatory decisions on CCL2 contaminants. Previous studies have examined vanadium adsorption onto some metal hydroxides but not onto commercially available adsorbents. This paper briefly summarizes known vanadium occurrence in North American groundwater and assesses vanadium removal by three commercially available metal oxide adsorbents with different mineralogies. GTO (Dow) is TiO2 based and E-33 (Seven Trents) and GFH (US Filter) are iron based. Preliminary vanadate adsorption kinetics onto GFH, E-33 and GTO has been studied and the homogenous surface diffusion model (HSDM) is used to describe the adsorption kinetics data. The effects of pH, vanadium concentration, and volume/mass ratio are assessed. Vanadium adsorption decreases with increasing pH, with maximum adsorption capacities achieved in at pH 3-4. Results indicate that all adsorbents remove vanadium; GFH has the highest adsorption capacity, followed by GTO and E-33. Data are best fit with the Langmuir model rather than Freundlich isotherms. Both the sorption maxima (Xm) and binding energy constant (b) follow the trend GFH>GTO>E-33. Naturally occurring vanadium is also removed from Arizona ground water in rapid small-scale column tests (RSSCTs). Metal oxide adsorption technologies currently used for arsenic removal may also remove vanadium but not always with the same effectiveness.
Article
A composite sorbent (GAC-QPVP) was prepared by coating poly(4-vinylpyridine) onto a granular activated carbon, followed by cross-linking and quaternization processes. The sorbent was characterized by scanning electron microscopy, point of zero charge measurement, and BET analysis. Batch experiments with variable pH, ionic strength, and concentrations of Cr(VI), sorbent, and competing anions were conducted to evaluate the selective sorption of Cr(VI) from aqueous solutions. The results showed that Cr(VI) sorption rates could be described by a reversible second-order kinetics, and equilibrium uptake of Cr(VI) increased with decreasing pH, decreasing ionic strength, and increasing sorbent concentration. The estimated maximum equilibrium uptake of chromium was 53.7 mg/g at pH = 2.25, 30.7 mg/g at pH = 3.65, and 18.9 mg/g at pH = 6.03, much higher than the maximum capacity of PVP-coated silica gel, an adsorbent for Cr examined previously. When compared with the untreated granular activated carbon, sorption onto GAC-QPVP resulted in much less Cr(VI) reduction and subsequent release of Cr(III). The effect of phosphate, sulfate, and nitrate was minor on the selective sorption of Cr(VI). An ion exchange model that was linked with aqueous speciation chemistry described Cr(VI) sorption reasonably well as a function of pH, ionic strength, and Cr(VI) concentration. Model simulations suggested that sorbed Cr(VI) was partially reduced to Cr(III) on the sorbent when pH was less than 4. The presence of Cr(III) on the sorbent was confirmed by the X-ray photoelectron spectroscopic analysis. Overall, the study has demonstrated that GAC-QPVP can effectively remove Cr(VI) from aqueous solutions under a wide range of experimental conditions, without significant Cr(III) release associated with the virgin GAC treatment.
  • M Li
M. Li, et al. Journal of Hazardous Materials 384 (2020) 121386