The dual effect of disodium anthraquinone-2,6-disulfonate (AQDS) on the Cr(VI) removal by biochar: The enhanced electron transfer and the inhibited adsorption

Xue Wang; Peng Zhang; Meixuan Wu; Ting He; Can Li; Lijuan Liu; Shunling Li; Zhaofeng Chang; Di Lang; Wei Du; Hao Li; Bo Pan

doi:10.1016/j.chemosphere.2023.140245

The dual effect of disodium anthraquinone-2,6-disulfonate (AQDS) on the Cr(VI) removal by biochar: The enhanced electron transfer and the inhibited adsorption

Chemosphere. 2023 Dec:343:140245. doi: 10.1016/j.chemosphere.2023.140245. Epub 2023 Sep 20.

Authors

Xue Wang¹, Peng Zhang², Meixuan Wu¹, Ting He¹, Can Li¹, Lijuan Liu¹, Shunling Li¹, Zhaofeng Chang¹, Di Lang¹, Wei Du¹, Hao Li¹, Bo Pan¹

Affiliations

¹ Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming, 650500, China.
² Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming, 650500, China. Electronic address: zhangpenviron@kust.edu.cn.

PMID: 37739129
DOI: 10.1016/j.chemosphere.2023.140245

Abstract

Due to large specific surface area, abundant surface functional groups, and stable chemical structure, biochar has been widely used in many environmental fields, including the remediation of Cr pollution. Alternatively, electrochemically active organic matter (e-OM), which is prevalent in both natural environments and industrial wastewater, exerts an inevitable influence on the mechanisms underlying Cr(VI) removal by biochar. The synergistic interplay between biochar and e-OM in the context of Cr(VI) remediation remains to be fully elucidated. In this study, disodium anthraquinone-2,6-disulfonate (AQDS) was used as a model for e-OM, characterized by its quinone group's ability to either donate or accept electrons. We found that AQDS sped up the Cr(VI) removal process, but the enhancement effect decreased with the increase in pyrolysis temperature. With the addition of AQDS, the removal amount of Cr(VI) by BC300 and BC600 increased by 160.0% and 49.5%, respectively. AQDS could release more electrons trapped in the lower temperature biochar samples (BC300 and BC600) for Cr(VI) reduction. However, AQDS inhibited the Cr(VI) removal by BC900 due to the adsorption of AQDS on biochar surface. In the presence of the small molecule carbon source lactate, more AQDS was adsorbed onto the biochar surface. This led to an inhibition of the electron transfer between biochar and Cr(VI), resulting in an inhibitory effect. This study has elucidated the electron transfer mechanism involved in the removal of Cr(VI) by biochar, particularly in conjunction with e-OM. Furthermore, it would augment the efficacy of biochar in applications targeting the removal of heavy metals.

Keywords: AQDS; Biochar; Chromium; Electron transfer.