A green approach towards simultaneous remediations of chromium(VI) and arsenic(III) in aqueous solution

Jiang, Bo; Guo, Jianbo; Wang, Zhaohui; Xing, Zheng; Zheng, Jingtang; Wu, Wenting; Wu, Mingbo; Xue, Qinzhong

doi:10.1016/j.cej.2014.10.064

Cited by 59 publications

(28 citation statements)

References 38 publications

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“…The pathway of As(III) being oxidized into As(V) is proposed as follows (eqs 10-13): [37,38] As(III) + •OH → As(IV) + OH¯ k = 9×10 9 M -1 s -1 (10) As(III) + •O2¯ + H + → As(IV) + HO2¯ k = 3.6×10 6 M -1 s -1 (11) As(IV) → As(III) + As(…”

Section: The Effects Of •O2¯ and •Oh On Arsenic Oxidationmentioning

confidence: 99%

“…During the oxidation process, As(IV) is the intermediated arsenic species, which will finally transform to As(V) via a As(IV) disproportionation reaction (eq 12) or by further oxidizing with the dissolved O2 (eq 13) [38]. From eq 10 and 11, it can be seen that the oxidation rate of As(III) by •OH is much higher than •O2¯.…”

Section: The Effects Of •O2¯ and •Oh On Arsenic Oxidationmentioning

confidence: 99%

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Visible-light photocatalysis accelerates As(III) release and oxidation from arsenic-containing sludge

Liu

et al. 2019

Applied Catalysis B: Environmental

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Arsenic containing sludge, a product of the treatment of acid smelting 2 wastewater, is susceptible to temperature, pH, co-existing salt ions and organic matter, which might lead to the release of arsenic ions into the environment. Here, we studied the effect of visible light on the dissolution and oxidation of arsenic sulfide sludge (ASS) sampled from a smelting plant. Results show that by exposure to visible light, both the release of As(III) ions from ASS and the oxidation of As(III) into As(V) were markedly accelerated. Electron paramagnetic resonance (EPR) and free radical quenching experiments revealed that ASS acts as a semiconductor photocatalyst to produce hydroxide and superoxide free radicals under visible light. At pH 7 and 11, both the dissolution and the oxidation of the sludge are directly accelerated by •O2¯. At pH 3, the dissolution of the sludge is promoted by both •O2¯ and •OH, while the oxidation of As(III) is mainly controlled by •OH. In addition, the solid phase of ASS was transformed to sulfur (S8) which favored the aggregation and precipitation of the sludge. The transformation was affected by the generation of intermediate sulfur species and sulfur-containing free radicals, as determined by ion chromatography and low-temperature EPR, respectively. A photocatalytic oxidation-based model is proposed to underpin the As(III) release and oxidation behavior of ASS under visible light conditions. This study helps to predict the fate of ASS deposited in the environment in a range of natural and engineered settings.

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Section: The Effects Of •O2¯ and •Oh On Arsenic Oxidationmentioning

confidence: 99%

Section: The Effects Of •O2¯ and •Oh On Arsenic Oxidationmentioning

confidence: 99%

Visible-light photocatalysis accelerates As(III) release and oxidation from arsenic-containing sludge

Liu

et al. 2019

Applied Catalysis B: Environmental

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“…However, the direct redox between Cr(VI) and As(III) under standard conditions is not possible due to the fact that the theoretical Gibbs free energy (Δ r G m ) of the reaction is 468 J· mol −1 ·K −1 . 13 Although some works have devised strategies to overcome the thermodynamic restriction of Cr(VI)/As(III) redox conversion, 14,15 these attempts are still far from meeting the demands of practical application.…”

Section: ■ Introductionmentioning

confidence: 99%

Redox Conversion of Chromium(VI) and Arsenic(III) with the Intermediates of Chromium(V) and Arsenic(IV) via AuPd/CNTs Electrocatalysis in Acid Aqueous Solution

Sun

Zhang

Qin

et al. 2015

Environ. Sci. Technol.

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Simultaneous reduction of Cr(VI) to Cr(III) and oxidation of As(III) to As(V) is a promising pretreatment process for the removal of chromium and arsenic from acid aqueous solution. In this work, the synergistic redox conversion of Cr(VI) and As(III) was efficiently achieved in a three-dimensional electrocatalytic reactor with synthesized AuPd/ CNTs particles as electrocatalysts. The AuPd/CNTs facilitated the exposure of active Pd{111} facets and possessed an approximate two-electrontransfer pathway of oxygen reduction with the highly efficient formation of H 2 O 2 as end product, resulting in the electrocatalytic reduction of 97.2 ± 2.4% of Cr(VI) and oxidation of 95.7 ± 4% of As(III). The electrocatalytic reduction of Cr(VI) was significantly accelerated prior to the electrocatalytic oxidation of As(III), and the effectiveness of Cr(VI)/As(III) conversion was favored at increased currents from 20 to 150 mA, decreased initial pH from 7 to 1 and concentrations of Cr(VI) and As(III) ranging from 50 to 1 mg/L. The crucial intermediates of Cr(V) and As(IV) and active free radicals HO• and O 2 •− were found for the first time, whose roles in the control of Cr(VI)/As(III) redox conversion were proposed. Finally, the potential applicability of AuPd/CNTs was revealed by their stability in electrocatalytic conversion over 10 cycles. ■ INTRODUCTIONThe combined pollution of heavy metals in acid wastewater has become a formidable problem to environmental scientists and engineers for decades. As a consequence of improper treatment, effluents containing abundant heavy metal ions such as lead, nickel, copper, arsenic, or chromium may inflow into surface water or seep into groundwater, which pose great threats to aquatic life and drinking water sources.1,2 Thus, it is urgent to remove the heavy metals prior to their discharge into the environment.Arsenic and chromium, as priority pollutants, are highly toxic and frequently coexist with highly acidic wastewater (e.g., acid mine drainage).3 The valence states of arsenic or chromium have decisive impacts on their environmental fate and toxic effect.4,5 For example, As(III) is the most prevalent form of arsenic in the natural environment, which is more toxic than As(V) to mammals. 6 Additionally, As(III) is also more mobile than As(V), because As(III) is quite easier originated from the oxidative weathering or reductive dissolution of As-containing minerals, suggesting the immobilization of As(III) in acid solution more strictly depends on the redox conditions. 7 Therefore, it is advisible to preoxidize As(III) to As(V), coupled with a following adsorption or coprecipitation of the As(V) by using adsorbents or coagulants, to finally enhance the removal of arsenic species in acid aqueous solution. 8,9 Similarly, Cr(VI) is quite soluble and mobile in acid wastewater, 10 whileCr(III) is less toxic and insoluble, and can be effectively immobilized as the hydroxide in a wide pH range. 11,12 Thus, the prereduction of Cr(VI) to Cr(III) is conducive to the complete removal of ch...

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“…However, the formation of the colloid phase on the solution surface can be used for developing new methods for removing metal ions from wastewaters. Growing interest to this is reflected in recent publications . Authors have used the direct current (DC) atmospheric pressure glow discharge for removal chromium(VI) as a model compound from aqueous solutions.…”

Section: Introductionmentioning

confidence: 99%

“…Growing interest to this is reflected in recent publications. [7][8][9][10][11][12][13] Authors have used the direct current (DC) atmospheric pressure glow discharge for removal chromium(VI) as a model compound from aqueous solutions. Using alternating current (AC) electrical discharges and radio frequency microplasmas are more appropriate for application because they do not require complicated equipment.…”

Section: Introductionmentioning

confidence: 99%

Plasma‐induced precipitation of metal ions in aqueous solutions

Khlyustova

Sirotkin

Титов

2019

J of Chemical Tech & Biotech

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BACKGROUND This work focuses on removing metal ions (Fe3+, Cu2+, and Zn2+) from aqueous solutions and real wastewater by underwater plasma. RESULTS Results show that the joint presence of Fe3+, Cu2+, and Zn2+ are needed for effective precipitation of these ions from aqueous solutions. The short‐time underwater plasma treatment leads to more effective removal of metal ions from real wastewater compared to treatment facilities of a factory. CONCLUSIONS Removing metal ions from aqueous solutions of their mixture by underwater plasma occurs via formation of non‐dissolved substances on the base of metal oxide/hydroxide. Efficient removal of metal ions from real wastewater allows the creation of a prototype setup as one of the blocks of treatment facilities at a chemical factory. © 2019 Society of Chemical Industry

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A green approach towards simultaneous remediations of chromium(VI) and arsenic(III) in aqueous solution

Cited by 59 publications

References 38 publications

Visible-light photocatalysis accelerates As(III) release and oxidation from arsenic-containing sludge

Visible-light photocatalysis accelerates As(III) release and oxidation from arsenic-containing sludge

Redox Conversion of Chromium(VI) and Arsenic(III) with the Intermediates of Chromium(V) and Arsenic(IV) via AuPd/CNTs Electrocatalysis in Acid Aqueous Solution

Plasma‐induced precipitation of metal ions in aqueous solutions

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