Simultaneous reduction of Cr(VI) and oxidation of As(III) by Bacillus firmus TE7 isolated from tannery effluent

Bachate, Sachin P.; Nandre, Vinod S.; Ghatpande, Niraj S.; Kodam, Kisan M.

doi:10.1016/j.chemosphere.2012.10.081

Cited by 89 publications

(28 citation statements)

References 34 publications

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“…However, the optimum tolerance for these cells could be found at 70 mg/L and 40 mg/L of Cr(VI) and As(III). These observations are in agreement with previous studies where Cr(VI) reduction was simultaneously achieved with As(III) oxidation (Bachate et al, 2013).…”

Section: Cr(vi) Reduction At Different As(iii) Concentrationssupporting

confidence: 83%

“…respectively. These suggests that Cr(VI) reduction was mediated by electron transfer from oxidation of As(III) to As(V), catalysed by membrane bound arsenite oxidase enzyme (Bachate, 2013). In the present study, As(III) concentrations were not quantified, and therefore, more studies is required to evaluate As(III) oxidation.…”

Section: Cr(vi) Reduction At Different As(iii) Concentrationsmentioning

confidence: 80%

“…Previously, it was established that microorganisms exposed to toxic metals/metalloid ions developed diverse resistance mechanisms to tolerate the toxicity of toxic metal ions (Bachate et al, 2013). These resistance mechanisms involve specific − 4 − biochemical pathways that can alter chemical properties of toxic metal ions, resulting in their detoxification (Silver and Phung, 2005).…”

Section: Methodsmentioning

confidence: 99%

“…Bachate et al, (2013) reported simultaneous Cr(VI) reduction and As(III) oxidation by Bacillus firmus TE7.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

Tony¹,

Chirwa²

2014

proc water environ fed

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Degree:Master of Engineering (Chemical Engineering)An indigenous mixed culture of bacteria collected from a Wastewater Treatment Plant (Brits, North West Province, South Africa), biocatalytically reduced Cr(VI) in the presence of As(III). Both the reduced chromium (Cr(III)) and the oxidised arsenic (As(V)) readily form amorphous hydroxides that can be easily separated or precipitated from the aqueous phase as part of the treatment process. Treatment of Cr(VI) and As(III) before disposal of wastewater is critical since both compounds are known to be carcinogenic and mutagenic at very low concentrations, and acutely toxic at high concentrations.Batch experiments were conducted to evaluate the rate of Cr(VI) reduction under anaerobic condition in the presence of its co-contaminant As(III) typically found in the groundwater and mining effluent. Results showed near complete Cr(VI) reduction under initial Cr(VI) concentrations up to 70 mg/L in a batch amended with 20 mg/L As(III). However, increasingCr(VI) concentrations up to 100 mg/L resulted in the inhibition of Cr(VI) reduction activity.Further investigation was conducted in a batch reactor amended with 70 mg/L Cr(VI) concentration at different As(III) concentrations ranging from 5-70 mg/L to evaluate the effect of varying As(III) concentration on Cr(VI) reduction efficiency. Results showed that Cr(VI) reduction efficiency increased as As(III) concentrations increased from 5-40 mg/L.However, further increase in As(III) concentration up to 50 mg/L resulted in incomplete Cr(VI) reduction and decrease in Cr(VI) reduction efficiency. These results suggest that the rate of Cr(VI) reduction depends on the redox reaction of As(III) and As(V) with Cr(VI).Moreover, the inhibitory effect observed at high Cr(VI) and As(III) concentration may also − ii − be attributed to the dual toxicity effect of Cr(VI) and As(III) on microbial cell. From the above batch kinetic studies lethal concentration of Cr(VI) and As(III) for these strains was evaluated and established.Initial evaluation of the bacteria using 16S rRNA partial sequence method showed that cells in the mixed culture comprised predominantly of the Gram-positive species: Staphylococcus sp., Enterobacter sp., and Bacillus sp. The biokinetic parameters of these strains were estimated using a non-competitive inhibition model with a computer programme for simulation of the Aquatic System "AQUASIM 2.0". Cr(VI) reduction efficiency along the longitudinal column was also evaluated in this study.Results showed that Cr(VI) efficiency increased as Cr(VI) concentration travels along the longitudinal column. Other important factors such as oxygen and pH during biological Cr(VI) reduction in the presence of As(III) oxidation were also evaluated.

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Section: Cr(vi) Reduction At Different As(iii) Concentrationssupporting

confidence: 83%

Section: Cr(vi) Reduction At Different As(iii) Concentrationsmentioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

“…Bachate et al, (2013) reported simultaneous Cr(VI) reduction and As(III) oxidation by Bacillus firmus TE7.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

Tony¹,

Chirwa²

2014

proc water environ fed

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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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Aspects of Mordants and Metal Complex Dyes

Vajpeyee

Singh

Maity

et al. 2022

Textile Dyes and Pigments

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Simultaneous reduction of Cr(VI) and oxidation of As(III) by Bacillus firmus TE7 isolated from tannery effluent

Cited by 89 publications

References 34 publications

Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

Kinetic Studies of Cr(VI) Reduction in an Indigenous Mixed Culture of Bacteria in the Presence of As(III)

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

Aspects of Mordants and Metal Complex Dyes

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