Removal of hexavalent chromium in aqueous solutions using biochar: Chemical and spectroscopic investigations

Anushka Upamali Rajapaksha; Md Samrat Alam; Ning Chen; Daniel S. Alessi; Avanthi Deshani Igalavithana; Daniel C.W. Tsang; Yong Sik Ok

doi:10.1016/j.scitotenv.2017.12.195

Removal of hexavalent chromium in aqueous solutions using biochar: Chemical and spectroscopic investigations

Anushka Upamali Rajapaksha, Md Samrat Alam, Ning Chen, Daniel S. Alessi, Avanthi Deshani Igalavithana, Daniel C.W. Tsang, Yong Sik Ok

Research output: Journal article publication › Journal article › Academic research › peer-review

193 Citations (Scopus)

Abstract

Biochar is an emerging low-cost sorbent used for removing trace metals from water. In this study, we evaluated the removal potential of aqueous hexavalent chromium (Cr(VI)) by biochars produced from soybean (Glycine max L.) and burcucumber (Sicyos angulatus L.) residues. The highest Cr(VI) removal from solution occurred at low pH values (pH 2–5), and adsorption decreased approximately tenfold when the pH increased from 2 to 10. Synchrotron-based X-ray absorption spectroscopy (XAS) investigations showed that Cr(VI) species were reduced to trivalent chromium (Cr(III)) at the biochar surface following Cr(VI) adsorption. Linear combination fitting (LCF) of X-ray absorption near edge structure (XANES) data indicated that approximately 90% of the total Cr(VI) (962 μM) was reduced to Cr(III). Extended X-ray absorption fine structure (EXAFS) fitting results yielded interatomic chromium (Cr–Cr) distances consistent with the formation of Cr(III) precipitates as Cr(OH)3. Trivalent chromium is far less soluble than Cr(VI) and typically precipitates as amorphous Cr(III) solids. Thus, biochars produced by soybean and burcucumber residues are a promising technique for both adsorbing and reductively immobilizing Cr(VI) from aqueous solutions.

Original language	English
Pages (from-to)	1567-1573
Number of pages	7
Journal	Science of the Total Environment
Volume	625
DOIs	https://doi.org/10.1016/j.scitotenv.2017.12.195
Publication status	Published - 1 Jun 2018

Keywords

Advanced spectroscopic technique
Biosorption
Black carbon
Charcoal
Slow pyrolysis

ASJC Scopus subject areas

Environmental Engineering
Environmental Chemistry
Waste Management and Disposal
Pollution

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10.1016/j.scitotenv.2017.12.195

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abstract = "Biochar is an emerging low-cost sorbent used for removing trace metals from water. In this study, we evaluated the removal potential of aqueous hexavalent chromium (Cr(VI)) by biochars produced from soybean (Glycine max L.) and burcucumber (Sicyos angulatus L.) residues. The highest Cr(VI) removal from solution occurred at low pH values (pH 2–5), and adsorption decreased approximately tenfold when the pH increased from 2 to 10. Synchrotron-based X-ray absorption spectroscopy (XAS) investigations showed that Cr(VI) species were reduced to trivalent chromium (Cr(III)) at the biochar surface following Cr(VI) adsorption. Linear combination fitting (LCF) of X-ray absorption near edge structure (XANES) data indicated that approximately 90% of the total Cr(VI) (962 μM) was reduced to Cr(III). Extended X-ray absorption fine structure (EXAFS) fitting results yielded interatomic chromium (Cr–Cr) distances consistent with the formation of Cr(III) precipitates as Cr(OH)3. Trivalent chromium is far less soluble than Cr(VI) and typically precipitates as amorphous Cr(III) solids. Thus, biochars produced by soybean and burcucumber residues are a promising technique for both adsorbing and reductively immobilizing Cr(VI) from aqueous solutions.",

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author = "Rajapaksha, {Anushka Upamali} and Alam, {Md Samrat} and Ning Chen and Alessi, {Daniel S.} and Igalavithana, {Avanthi Deshani} and Tsang, {Daniel C.W.} and Ok, {Yong Sik}",

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AU - Alam, Md Samrat

AU - Chen, Ning

AU - Alessi, Daniel S.

AU - Igalavithana, Avanthi Deshani

AU - Tsang, Daniel C.W.

AU - Ok, Yong Sik

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AB - Biochar is an emerging low-cost sorbent used for removing trace metals from water. In this study, we evaluated the removal potential of aqueous hexavalent chromium (Cr(VI)) by biochars produced from soybean (Glycine max L.) and burcucumber (Sicyos angulatus L.) residues. The highest Cr(VI) removal from solution occurred at low pH values (pH 2–5), and adsorption decreased approximately tenfold when the pH increased from 2 to 10. Synchrotron-based X-ray absorption spectroscopy (XAS) investigations showed that Cr(VI) species were reduced to trivalent chromium (Cr(III)) at the biochar surface following Cr(VI) adsorption. Linear combination fitting (LCF) of X-ray absorption near edge structure (XANES) data indicated that approximately 90% of the total Cr(VI) (962 μM) was reduced to Cr(III). Extended X-ray absorption fine structure (EXAFS) fitting results yielded interatomic chromium (Cr–Cr) distances consistent with the formation of Cr(III) precipitates as Cr(OH)3. Trivalent chromium is far less soluble than Cr(VI) and typically precipitates as amorphous Cr(III) solids. Thus, biochars produced by soybean and burcucumber residues are a promising technique for both adsorbing and reductively immobilizing Cr(VI) from aqueous solutions.

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KW - Biosorption

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Removal of hexavalent chromium in aqueous solutions using biochar: Chemical and spectroscopic investigations

Abstract

Keywords

ASJC Scopus subject areas

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