Immobilization of Cr(III) and Cr(VI) from contaminated aqueous solution by using sewage produced biochar: Affecting factors and mechanisms

ABSTRACT

The present study focuses on adsorption of chromium (trivalent and hexavalent) by using sewage-produced biochar as well as reduction of the produced sewage. Biochar is produced from municipal sewage to examine the capability of two biochars i.e., prepared at 450°C SWB450 and 550°C SWB550 to sorb trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] using batch experiments. Brunauer Emmett Teller (BET) data indicated higher surface area of SWB550 compared to SWB450, which supports the field emission scanning electron microscope (FESEM) results. 4 g L⁻¹ biochar doses emerged as the optimum for Cr(III) and Cr(VI) removal for both biochars at pH 5.0. Performance of SWB550 was 92.9% for Cr(III) and <40% removal for Cr(VI). Energy dispersive X-ray (EDX) spectroscopy and Fourier transformation infrared (FTIR) study confirmed the Cr loading on both the biochars. Adsorption isotherm and kinetic models confirmed that the mechanisms behind the sorption of trivalent and hexavalent Cr on SWB450 and 550 biochar were physical sorption and chemical sorption processes. Adsorption via biochar is a cost-effective and simple process compared to electrodialysis, ion exchange, chemical precipitation, membrane filtration, electrocoagulation, bioremediation, photocatalysis, etc. Present study provides an effective biochar for Cr removal from wastewater as well as reduction in the generated waste through pyrolysis.

KEYWORDS:

• Chromium
• adsorption
• biochar
• sewage
• wastewater

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

Manash Gope: Conceptualization, Methodology, Validation, Data curation, Investigation, Formal analysis, Software, Visualization, Writing-original draft preparation, Reviewing and Editing. Anibrata Das: Software, Formal analysis. Sandip Mondal: Formal analysis, Supervision.

Apurba Ratan Ghosh: Supervision, Reviewing and Editing. Rajnarayan Saha: Supervision, Visualization, Validation, Reviewing and Editing.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2022.2088899

Additional information

Funding

The first author appreciates the financial assistance provided by the N-PDF scheme (Project No. PDF/2017/000530) of the DST-SERB.