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Lixiang Zhou - One of the best experts on this subject based on the ideXlab platform.
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Co-adsorption of As(III) and phenanthrene by Schwertmannite and Fenton-like regeneration of spent Schwertmannite to realize phenanthrene degradation and As(III) oxidation
Environmental research, 2021Co-Authors: Xiaoqing Meng, Xiaomeng Wang, Chunmei Zhang, Su Yan, Guanyu Zheng, Lixiang ZhouAbstract:ABSTRACT Co-contamination of arsenic and polycyclic aromatic hydrocarbons (PAHs) in groundwater is frequently reported, and it is thus necessary to develop efficient techniques to tackle this problem. Here, we evaluated the feasibility of utilizing Schwertmannite to co-adsorb As(III) and phenanthrene from water solution and regenerating spent Schwertmannite via a heterogeneous Fenton-like reaction to degrade adsorbed phenanthrene and meanwhile oxidize adsorbed As(III). The results suggested that Schwertmannite with a hedgehog-like morphology was superior to that with a smooth surface for the adsorption removal of As(III) or phenanthrene because of the much higher BET surface area and hydroxyl proportion of the former one, and Schwertmannite formed at 72 h incubation effectively co-adsorbed As(III) and phenanthrene from water solution. The adsorption of As(III) and phenanthrene on Schwertmannite did not interfere with each other, while the acidic initial solution pH delayed the adsorption of As(III) on Schwertmannite but enhanced the adsorption capacity for phenanthrene. The adsorption of As(III) on Schwertmannite mainly involved its exchange with SO42- (outer-sphere or inner-sphere) and its complexation with iron hydroxyl surface groups, and phenanthrene adsorption mainly occurred through cation-π bonding and OH-π interaction. During the adsorption-regeneration processes, Schwertmannite absorbed As(III) and phenanthrene firstly, and then it can be successfully regenerated via Fenton-like reaction catalyzed by itself to effectively degrade the adsorbed phenanthrene and meanwhile oxidize the adsorbed As(III) to As(V). Therefore, schwertmanite is an outstanding environmental adsorbent to decontaminate As(III) and phenanthrene co-existing in groundwater.
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Hydroxyl, Fe2+, and Acidithiobacillus ferrooxidans Jointly Determined the Crystal Growth and Morphology of Schwertmannite in a Sulfate-Rich Acidic Environment.
ACS omega, 2021Co-Authors: Kun Feng, Xiaomeng Wang, Bo Zhou, Jianru Liang, Lixiang ZhouAbstract:Schwertmannite, ubiquitously found in iron and sulfate-rich acid mine drainage, is generated via biological oxidation of ferrous ions by Acidithiobacillus ferrooxidans (A. ferrooxidans). However, little information on the mechanisms of biogenic Schwertmannite formation and crystal growth is available. This study deliberately investigated the relationships among mineral morphology, solution chemistry, and phase transformation of Schwertmannite in A. ferrooxidans-containing ferrous sulfate solutions. The formation of Schwertmannite could be divided into three stages. In the first nucleation stage, crystallites are presented as nonaggregative or aggregative forms via a successive polymerization process. In the second stage, ellipsoidal aggregates, which are identified as ferrihydrite and/or Schwertmannite, are formed. In the third stage, needles appear on the surface of ellipsoidal aggregates, which is caused by the phase transformation of ferrihydrite or Schwertmannite to lepidocrocite and goethite through a Fe2+ (aq) catalysis-driven pathway. After three stages, a typical characteristic "hedgehog" morphology finally appears. In addition, A. ferrooxidans could significantly speed up the mineral transformation. Solution pH affects the morphology of Schwertmannite by acid leaching. The experimental results also reveal that the formation of Schwertmannite depend on the content of hydroxyl complexes or the transformation of the monomers to polymers, which are greatly affected by the solution pH.
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Synthesis and assessment of Schwertmannite/few-layer graphene composite for the degradation of sulfamethazine in heterogeneous Fenton-like reaction
Royal Society open science, 2020Co-Authors: Dianzhan Wang, Zhaoshun Yang, Lixiang ZhouAbstract:Schwertmannite (sch), an iron oxyhydrosulfate mineral, can catalyse a Fenton-like reaction to degrade organic contaminants, but the reduction of Fe(III) to Fe(II) on the surface of Schwertmannite i...
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heterogeneous fenton like degradation of phenanthrene catalyzed by Schwertmannite biosynthesized using acidithiobacillus ferrooxidans
RSC Advances, 2017Co-Authors: Xiaoqing Meng, Su Yan, Guanyu Zheng, Lixiang ZhouAbstract:Heterogeneous Fenton-like degradation of phenanthrene in aqueous solution was investigated using Schwertmannite biosynthesized by Acidithiobacillus ferrooxidans LX5 as a catalyst. The effects of different reaction parameters including catalyst loading, H2O2 concentration, initial solution pH and inorganic anions on the Fenton-like degradation of phenanthrene were studied. Results showed that the biosynthesized Schwertmannite had an effective catalytic ability on phenanthrene degradation. The degradation efficiency of phenanthrene was 99.0% within 3–5 h reaction under conditions of H2O2 200 mg L−1, Schwertmannite 1 g L−1, phenanthrene 1 mg L−1 and pH 3.0–4.5. The degradation was mainly via a surface mechanism, in which phenanthrene was readily adsorbed on the surface of Schwertmannite and then oxidized by ˙OH produced from H2O2 decomposition. The XPS results of Schwertmannite before and after Fenton-like degradation of phenanthrene revealed the change of Fe2+/Fe3+ species on the surface of Schwertmannite. Moreover, phthalates, octadecanoic acid and 9,10-phenanthraquinone were identified by GC-MS analyses as the main intermediate compounds during phenanthrene degradation, and all the intermediates were finally mineralized. The repeated use of biosynthesized Schwertmannite for phenanthrene degradation illustrated its stability and reusability as a Fenton-like catalyst. Therefore, Schwertmannite biosynthesized using A. ferrooxidans is an excellent catalyst for the degradation of phenanthrene in heterogeneous Fenton-like reactions.
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Schwertmannite synthesis through ferrous ion chemical oxidation under different h2o2 supply rates and its removal efficiency for arsenic from contaminated groundwater
PLOS ONE, 2015Co-Authors: Fenwu Liu, Lixiang Zhou, Jun Zhou, Shasha Zhang, Lanlan Liu, Wenhua FanAbstract:Schwertmannite-mediated removal of arsenic from contaminated water has attracted increasing attention. However, Schwertmannite chemical synthesis behavior under different H2O2 supply rates for ferrous ions oxidation is unclear. This study investigated pH, ferrous ions oxidation efficiency, and total iron precipitation efficiency during Schwertmannite synthesis by adding H2O2 into FeSO4·7H2O solution at different supply rates. Specific surface area and arsenic (III) removal capacity of Schwertmannite have also been studied. Results showed that pH decreased from ~3.48 to ~1.96, ~2.06, ~2.12, ~2.14, or ~2.17 after 60 h reaction when the ferrous ions solution received the following corresponding amounts of H2O2: 1.80 mL at 2 h (treatment 1); 0.90 mL at 2 h and 14 h (treatment 2); 0.60 mL at 2, 14, and 26 h (treatment 3); 0.45 mL at 2, 14, 26, and 38 h (treatment 4), or 0.36 mL at 2, 14, 26, 38, and 50 h (treatment 5). Slow H2O2 supply significantly inhibited the total iron precipitation efficiency but improved the specific surface area or arsenic (III) removal capacity of Schwertmannite. For the initial 50.0 μg/L arsenic (III)-contaminated water under pH ~7.0 and using 0.25 g/L Schwertmannite as an adsorbent, the total iron precipitation efficiency, specific surface area of the harvested Schwertmannite, and Schwertmannite arsenic(III) removal efficiency were 29.3%, 2.06 m2/g, and 81.1%, respectively, in treatment 1. However, the above parameters correspondingly changed to 17.3%, 16.30 m2/g, and 96.5%, respectively, in treatment 5.
Yeqing Lan - One of the best experts on this subject based on the ideXlab platform.
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Biogenic synthetic Schwertmannite photocatalytic degradation of acid orange 7 (AO7) assisted by citric acid
Separation and Purification Technology, 2015Co-Authors: Jing Guo, Chao Dong, Jing Zhang, Yeqing LanAbstract:Abstract Schwertmannite was synthesized through the oxidation of FeSO 4 by Acidithiobacillus ferrooxidans LX5 cell suspension and characterized using X-ray diffraction spectroscopy (XRD) and scanning electron microscope (SEM). Schwertmannite photocatalytic degradation of acid orange 7 (AO7) assisted by citric acid was further investigated at different initial pH values and different concentrations of Schwertmannite or citric acid. The results showed that it was difficult for AO7 to be discomposed by Schwertmannite or citric acid alone under UV irradiation. However, the removal of AO7 was significantly enhanced when biogenic Schwertmannite and citric acid coexisted in the reaction system. Low pH and high initial concentrations of citric acid and Schwertmannite were beneficial to the degradation of AO7. Hydroxyl radical ( OH) and Fe(II), the intermediates, were investigated during the reactions to reveal their correlation with the degradation of AO7. A possible mechanism for biogenic Schwertmannite photocatalytic decomposition of AO7 in the presence of citric acid was proposed.
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Facilitating role of biogenetic Schwertmannite in the reduction of Cr(VI) by sulfide and its mechanism.
Journal of hazardous materials, 2012Co-Authors: Peng Zhou, Yeqing Lan, Yuxiao Shen, Lixiang ZhouAbstract:The efficient conversion of Cr(VI) to Cr(III) has attracted an increasing concern in recent years owing to its threat to the environment. In the present paper, the catalytic role of biogenetic Schwertmannite in the reduction of Cr(VI) by sulfide and its mechanism were investigated under different conditions through batch experiments. The results demonstrated that Schwertmannite markedly accelerated the removal of Cr(VI) by sulfide, and the rates of the reaction were enhanced by 11, 8 and 6 times, respectively at pH 7.5, 8.0 and 8.8 as compared with control (no Schwertmannite). In addition, the conversion of Cr(VI) into Cr(III) increased with Schwertmannite loading and temperature. However, the facilitating role of Schwertmannite in the reduction of Cr(VI) by sulfide was markedly suppressed by an introduction of F(-), a complex agent for Fe(III). It is concluded that the catalysis of Schwertmannite results from the activated Fe(III) on the surface of Schwertmannite, serving as a "bridge" in the transportation of electrons between sulfide and Cr(VI), and leading to the improving reduction of Cr(VI) by sulfide.
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Photocatalytic reduction of Cr(VI) by small molecular weight organic acids over Schwertmannite.
Chemosphere, 2012Co-Authors: Danjun Jiang, Yeqing Lan, Pei Zhou, Lixiang ZhouAbstract:In this study, a series of bath experiments was carried out to investigate the photoreduction of Cr(VI) by small molecular weight organic acids (SOAs) over Schwertmannite, a mineral found in acid mine drainage (AMD). The results demonstrated that Schwertmannite or SOAs alone was unable to effectively transform Cr(VI) to Cr(III) even if exposed to an illumination of mimic solar light. However, an addition of Schwertmannite significantly enhanced the reduction of Cr(VI) by SOAs under the same condition. For example, 100μM Cr(VI) was almost completely removed within 50min in the presence of both Schwertmannite (0.6gL(-1)) and oxalic acid (300μM) at pH 3.0. The photocatalytic reduction of Cr(VI) was strongly influenced by pH, the initial concentrations and the structures of SOAs. Of the tested three SOAs, the reaction rates of photocatalytic reduction of Cr(VI) were in the order of oxalic acid>citric acid>tartaric acid. The reaction obeyed to zero-order kinetics with respect to Cr(VI) with excess SOAs. A possible mechanism for photoreduction of Cr(VI) by SOAs over Schwertmannite was proposed. Fe(III) on the surface of Schwertmannite was dissolved by SOAs, and then Fe(III)-SOA complexes with high photochemical activity formed. Further, Fe(II) together with organic acid radicals, CO(2)(-) and O(2)(-), was generated through a metal-ligand-charge-transfer pathway (MLCT), leading to a rapid reduction of Cr(VI).
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Heterogeneous photocatalytic degradation of methyl orange in Schwertmannite/oxalate suspension under UV irradiation
Environmental science and pollution research international, 2012Co-Authors: Jing Guo, Yeqing Lan, Danjun Jiang, Pei Zhou, Lixiang ZhouAbstract:Schwertmannite was synthesized through an oxidation of FeSO(4) by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28°C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The Schwertmannite photocatalytic degradation of methyl orange (MO) by oxalate was investigated at different initial pH values, concentrations of Schwertmannite, oxalate, and MO. The results demonstrated that photodegradation of MO in the presence of Schwertmannite or oxalate alone was very weak. However, the removal of MO was significantly enhanced when Schwertmannite and oxalate coexisted in the reaction system. Low pH (4 or less) was beneficial to the degradation of MO. The optimal doses of Schwertmannite and oxalate were 0.2 g L(-1) and 2 mM, respectively. Hydroxyl radicals (·OH) and Fe(II), the intermediate products, were also examined during the reaction to explore their correlation with the degradation of MO. A possible mechanism for the photocatalytic decomposition of MO in the study was proposed. The formation of Fe(III)-oxalate complexes on the surface of Schwertmannite was a precursor of H(2)O(2) and Fe(II) production, further leading to the yield of ·OH responsible for the decomposition of MO.
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heterogeneous photocatalytic degradation of methyl orange in Schwertmannite oxalate suspension under uv irradiation
Environmental Science and Pollution Research, 2012Co-Authors: Jing Guo, Yeqing Lan, Danjun Jiang, Pei Zhou, Lixiang ZhouAbstract:Introduction Schwertmannite was synthesized through an oxidation of FeSO4 by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28°C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The Schwertmannite photocatalytic degradation of methyl orange (MO) by oxalate was investigated at different initial pH values, concentrations of Schwertmannite, oxalate, and MO.
Edward D Burton - One of the best experts on this subject based on the ideXlab platform.
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Contrasting effects of phosphate on the rapid transformation of Schwertmannite to Fe(III) (oxy)hydroxides at near-neutral pH
Geoderma, 2019Co-Authors: Valerie A. Schoepfer, Edward D Burton, Scott G JohnstonAbstract:Abstract Schwertmannite is a metastable Fe(III)-bearing mineral that can rapidly transform to more stable Fe(III) oxides upon Fe(II) sorption, via a dissolution-reprecipitation pathway. Phosphate (PO43−) is a nutrient found in varying quantities in natural systems, but the influence of PO43− on the Fe(II) induced transformation of Schwertmannite is not well characterized. Here, we aim to quantify the aqueous and mineralogical effects of varied PO43− loading, and subsequent Fe(II) loading, to Schwertmannite at circumneutral pH. Phosphate was presorbed to Schwertmannite at loadings of 0, 80, 400 and 800 μmoles g−1 in anoxic artificial groundwater. Fe(II) was then added at a final concentration of 12.5 mM and aqueous and mineralogical products were observed over 10 days. No transformation occurred before Fe(II) addition in the zero PO43− treatment. In contrast, the three highest PO43− treatments partially transformed to a microcrystalline Fe(III) oxyhydroxide before Fe(II) addition, possibly due to exchange of sulfate with the added PO43−. Within 1 h of subsequent Fe(II) addition in the zero PO43−treatment, all Schwertmannite had transformed to goethite via the Fe(II)-induced transformation pathway. Increases in the level of PO43− loading attenuated goethite precipitation via Fe(II)-induced transformation of the precursor Schwertmannite and microcrystalline Fe(III) oxyhydroxide, with 65%, 34%, and 21% solid phase Fe as goethite at day 10 in the low (80 μmoles g−1), medium (400 μmoles g−1) and high (800 μmoles g−1) PO43− treatments. Under low PO43− loading, the addition of Fe(II) induced the transformation of the microcrystalline Fe(III) oxyhydroxide and Schwertmannite to a mixture of lepidocrocite and goethite. In the medium and high PO43− treatments, Schwertmannite and the microcrystalline Fe(III) oxyhydroxide were instead stabilized by surface-complexation of PO43− and did not extensively transform to more crystalline phases. Overall, the results show that PO43− loadings can both drive rapid Schwertmannite transformation to a new microcrystalline Fe(III) oxyhydroxide phase, and subsequently inhibit the Fe(II)-induced formation of lepidocrocite and goethite.
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Phosphate loading alters Schwertmannite transformation rates and pathways during microbial reduction.
The Science of the total environment, 2018Co-Authors: Valerie A. Schoepfer, Edward D Burton, Scott G Johnston, Peter KraalAbstract:Abstract Acid sulfate systems commonly contain the metastable ferric oxyhydroxysulfate mineral Schwertmannite, as well as phosphate (PO43−) - a nutrient that causes eutrophication when present in excess. However, acid sulfate systems often experience reducing conditions that destabilize Schwertmannite. Under such conditions, the long-term fate of both Schwertmannite and PO43− may be influenced by interactions during microbially-mediated Fe(III) and SO42− reduction. This study investigates the influence of PO43− on Fe(III) and SO42− reduction and the subsequent mineralogical transformation(s) in Schwertmannite-rich systems exposed to reducing conditions. To accomplish this, varied PO43− loadings were established in microbially-inoculated Schwertmannite suspensions that were incubated under anoxic conditions for 82 days. Increased PO43− attenuated the onset of microbial Fe(III) reduction. This delayed consequent pH increases, which in turn had cascading effects on the initiation of SO42− reduction and subsequent mineral species formed. Under zero PO43− loading, goethite (αFeOOH) formed first, followed by mackinawite (FeS) and siderite (FeCO3). In contrast, in higher PO43− treatments, vivianite (Fe3(PO4)2) and/or sulfate green rust (FeII4FeIII2(OH)12SO4) became increasingly important over time at the expense of goethite and mackinawite compared to PO43−-free conditions. The findings imply that PO43− loading alters the rates and onset of microbial Fe(III)- and SO42−- reduction and the subsequent formation of secondary Fe-bearing phases. In addition, Schwertmannite reduction and the associated mineralogical evolution under anoxic conditions appears to sequester large quantities of PO43− in the form of green rusts and vivianite.
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Chromium(III) substitution inhibits the Fe(II)-accelerated transformation of Schwertmannite.
PloS one, 2018Co-Authors: Girish Choppala, Edward D BurtonAbstract:Schwertmannite is an Fe(III)-oxyhydroxysulfate which is common in acid mine drainage (AMD) and acid sulfate soil (ASS) environments. Natural Schwertmannite is often enriched in Cr(III), yet the effects of Cr(III) substitution on Schwertmannite transformation to more stable Fe(III) minerals has not been addressed. Here we examine, for the first time, the effects of Cr(III) substitution on the Fe(II)-accelerated transformation of Schwertmannite. X-ray diffraction (XRD) and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy shows that Cr(III) substitution inhibits Schwertmannite transformation. Substitution at a Cr(III):Fe(III) ratio of 0.025 decreased Schwertmannite transformation (at pH 6.5) by 18-49% (depending on Fe(II) concentrations) relative to that of Cr(III)-free Schwertmannite. Formation of crystalline secondary phases (predominantly goethite) caused associated decreases in solid-phase Fe and Cr extractability by 1 M HCl. The extractability of Cr was consistently greater than that of Fe, suggesting some accumulation of Cr(III) at the residual Schwertmannite surface-a phenomenon which passivates the surface against Fe(II)/Fe(III) electron transfer and atom exchange required for the Fe(II)-accelerated transformation process. The finding that Cr(III)-substitution inhibits Schwertmannite transformation implies that it may also significantly impact associated Fe, S and trace metal(loid) behaviour.
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Scanning electron micrographs (SEM) of zero Cr(III)- and Cr(III)-incorporated Schwertmannite.
2018Co-Authors: Girish Choppala, Edward D BurtonAbstract:(A1, A2) zero Cr(III)- Schwertmannite with large spheroids; (B) low; (C) medium and, (D1 and D2) high Cr(III)- incorporated Schwertmannite.
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HRTEM micrographs.
2018Co-Authors: Girish Choppala, Edward D BurtonAbstract:(A) Cr(III)-free Schwertmannite; (B) FFT pattern of area enclosed by dashed-line in (A); (C) TEM-EDX spectrum of zero Cr(III)-Schwertmannite; (D) high Cr(III)-Schwertmannite; (E) FFT pattern of the area enclosed by dashed-line in (D); (F) EDX spectrum of high Cr(III)-Schwertmannite; (G) high Cr(III)-Schwertmannite sample that was treated with 10 mM Fe(II) after 14 days, (H) corresponding FFT pattern of the area enclosed by dashed line in (G) and (I) elemental mapping of sample shows Cr distribution.
Honghan Chen - One of the best experts on this subject based on the ideXlab platform.
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Effects of hydrogen-peroxide supply rate on Schwertmannite microstructure and chromium(VI) adsorption performance.
Journal of hazardous materials, 2018Co-Authors: Zhuo Zhang, Guanlin Guo, Qianchen Zhao, Honghan ChenAbstract:Abstract Schwertmannite has attracted increasing interest for its excellent sorption for pollutants such as arsenite [As(III)] and arsenate [As(V)]. Limited studies were conducted with hexavalent chromium [Cr(VI)], especially for Schwertmannite synthesized through Fe2+ oxidation. The effect of the hydrogen-peroxide (H2O2) supply rate on the structural characteristics and Cr(VI) adsorption capacity of Schwertmannite is unclear. The morphology, crystallinity, specific surface area (SSA), pore volume and Cr(VI) adsorption of Schwertmannite through Fe2+ oxidation at different H2O2 supply rates were analyzed. A slow H2O2 supply could improve the Schwertmannite SSA and pore volume. Schwertmannite changed from nanoparticle aggregates (169.31 m2/g SSA, 0.20 cm3/g pore volume) to ball-with-whisker-shaped particles (228.75 m2/g SSA, 0.30 cm3/g pore volume) with a lower H2O2 supply rate. The Cr(VI) adsorption capacity increased by 6.25%–11.70% at different given Cr(VI) concentrations. The maximum Cr(VI) adsorption capacity of Schwertmannite was 1.89 mmol/g at pH 6.0. Cr(VI) adsorption onto Schwertmannite may be attributed mainly to ion exchange with the structural SO42–. More than 91% of the original Cr(VI) adsorption capacity was maintained after four recycles. This study provides novel insights into the effects of H2O2 supply rate on the microstructure of Schwertmannite and its adsorption capacity for Cr(VI) in aqueous medium.
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Schwertmannite: occurrence, properties, synthesis and application in environmental remediation
RSC Advances, 2018Co-Authors: Zhuo Zhang, Qiancheng Zhao, Honghan ChenAbstract:Schwertmannite is a typical iron-derived mineral, which was originally discovered in acid mine drainings and subsequently synthesized in the laboratory. Increasingly, it is seen as having considerable potential as an adsorbent material, which could be used for environmental remediation (such as the treatment/remediation of arsenic, chromium, antimony, fluoride, and organic contaminants). This study reviews current developments, mainly in the preparation, structure, and water treatment of Schwertmannite. Several key issues are discussed in detail, such as synthetic strategy, the structure–property relationships, potential environmental applications, and related mechanisms. Soil remediation by Schwertmannite is compared to water treatment, and its application is further evaluated. Finally, the methodologies for water treatment and soil remediation using Schwertmannite are also taken into consideration from an environmental point of view.
Jing Guo - One of the best experts on this subject based on the ideXlab platform.
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Biogenic synthetic Schwertmannite photocatalytic degradation of acid orange 7 (AO7) assisted by citric acid
Separation and Purification Technology, 2015Co-Authors: Jing Guo, Chao Dong, Jing Zhang, Yeqing LanAbstract:Abstract Schwertmannite was synthesized through the oxidation of FeSO 4 by Acidithiobacillus ferrooxidans LX5 cell suspension and characterized using X-ray diffraction spectroscopy (XRD) and scanning electron microscope (SEM). Schwertmannite photocatalytic degradation of acid orange 7 (AO7) assisted by citric acid was further investigated at different initial pH values and different concentrations of Schwertmannite or citric acid. The results showed that it was difficult for AO7 to be discomposed by Schwertmannite or citric acid alone under UV irradiation. However, the removal of AO7 was significantly enhanced when biogenic Schwertmannite and citric acid coexisted in the reaction system. Low pH and high initial concentrations of citric acid and Schwertmannite were beneficial to the degradation of AO7. Hydroxyl radical ( OH) and Fe(II), the intermediates, were investigated during the reactions to reveal their correlation with the degradation of AO7. A possible mechanism for biogenic Schwertmannite photocatalytic decomposition of AO7 in the presence of citric acid was proposed.
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Heterogeneous photocatalytic degradation of methyl orange in Schwertmannite/oxalate suspension under UV irradiation
Environmental science and pollution research international, 2012Co-Authors: Jing Guo, Yeqing Lan, Danjun Jiang, Pei Zhou, Lixiang ZhouAbstract:Schwertmannite was synthesized through an oxidation of FeSO(4) by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28°C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The Schwertmannite photocatalytic degradation of methyl orange (MO) by oxalate was investigated at different initial pH values, concentrations of Schwertmannite, oxalate, and MO. The results demonstrated that photodegradation of MO in the presence of Schwertmannite or oxalate alone was very weak. However, the removal of MO was significantly enhanced when Schwertmannite and oxalate coexisted in the reaction system. Low pH (4 or less) was beneficial to the degradation of MO. The optimal doses of Schwertmannite and oxalate were 0.2 g L(-1) and 2 mM, respectively. Hydroxyl radicals (·OH) and Fe(II), the intermediate products, were also examined during the reaction to explore their correlation with the degradation of MO. A possible mechanism for the photocatalytic decomposition of MO in the study was proposed. The formation of Fe(III)-oxalate complexes on the surface of Schwertmannite was a precursor of H(2)O(2) and Fe(II) production, further leading to the yield of ·OH responsible for the decomposition of MO.
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heterogeneous photocatalytic degradation of methyl orange in Schwertmannite oxalate suspension under uv irradiation
Environmental Science and Pollution Research, 2012Co-Authors: Jing Guo, Yeqing Lan, Danjun Jiang, Pei Zhou, Lixiang ZhouAbstract:Introduction Schwertmannite was synthesized through an oxidation of FeSO4 by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28°C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The Schwertmannite photocatalytic degradation of methyl orange (MO) by oxalate was investigated at different initial pH values, concentrations of Schwertmannite, oxalate, and MO.
