Polyaniline@magnetic chitosan nanomaterials for highly efficient simultaneous adsorption and in-situ chemical reduction of hexavalent chromium: Removal efficacy and mechanisms

Chao Lei; Chunwei Wang; Wenqian Chen; Miaohua He; Binbin Huang

doi:10.1016/j.scitotenv.2020.139316

Polyaniline@magnetic chitosan nanomaterials for highly efficient simultaneous adsorption and in-situ chemical reduction of hexavalent chromium: Removal efficacy and mechanisms

Sci Total Environ. 2020 Sep 1:733:139316. doi: 10.1016/j.scitotenv.2020.139316. Epub 2020 May 11.

Authors

Chao Lei¹, Chunwei Wang², Wenqian Chen³, Miaohua He¹, Binbin Huang⁴

Affiliations

¹ School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410114, PR China.
² School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410114, PR China; College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
³ Department of Chemical Engineering and Technology, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
⁴ College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China. Electronic address: binbinhuang@hnu.edu.cn.

PMID: 32447080
DOI: 10.1016/j.scitotenv.2020.139316

Abstract

Devising new versatile nano-adsorbents for efficient capturing of heavy metals in water represents one important direction for environmental remediation. Here, the application of a novel polyaniline@magnetic chitosan (PANI@MCTS) composite consisting of numerous nitrogen-containing functional groups and magnetic Fe₃O₄ nanoparticles was reported for the efficient treatment of chromium-containing wastewater. This material exhibited a fast adsorption kinetics (80% removal efficiency within 15 min) and strong adsorption capacity (186.6 mg(Cr(VI))•g^-1(PANI@MCTS)) for removing Cr(VI) in water as well as an excellent magnetic separation ability. The adsorption of Cr(VI) was found to follow the Langmuir isotherm model and comply with the pseudo-second-order kinetics. More importantly, the PANI@MCTS could facilitate the in-situ chemical reduction of Cr(VI) to Cr(III) that enabled the detoxification treatment of Cr(VI) in water. XPS analysis revealed the simultaneous adsorption and in-situ chemical reduction of Cr(VI) on the PANI@MCTS, where the coordination and electrostatic interaction between Cr(VI) and the positively charged nitrogen containing functional groups contributed to the adsorption, and the = N-/-NH- groups served as active redox pair triggered the in-situ chemical reduction reaction. The recycle experiment showed an excellent stability of this material with >90% removal efficiency after five repeats of treatment. This work provides a promising alternative material for the effective treatment of chromium-containing wastewater.

Keywords: Adsorption; Cr(VI); In-situ chemical reduction; Magnetic chitosan; Polyaniline.