Boosting Cr(VI) detoxification and sequestration efficiency with carbon nanotube electrochemical filter functionalized with nanoscale polyaniline: Performance and mechanism

Yanbiao Liu; Fuqiang Liu; Ning Ding; Chensi Shen; Fang Li; Liming Dong; Manhong Huang; Bo Yang; Zhiwei Wang; Wolfgang Sand

doi:10.1016/j.scitotenv.2019.133926

Boosting Cr(VI) detoxification and sequestration efficiency with carbon nanotube electrochemical filter functionalized with nanoscale polyaniline: Performance and mechanism

Sci Total Environ. 2019 Dec 10:695:133926. doi: 10.1016/j.scitotenv.2019.133926. Epub 2019 Aug 14.

Authors

Yanbiao Liu¹, Fuqiang Liu², Ning Ding³, Chensi Shen⁴, Fang Li⁴, Liming Dong³, Manhong Huang⁴, Bo Yang², Zhiwei Wang⁵, Wolfgang Sand⁶

Affiliations

¹ Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China; Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai 200092, China. Electronic address: yanbiaoliu@dhu.edu.cn.
² Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
³ Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China.
⁴ Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China; Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai 200092, China.
⁵ Shanghai Institute of Pollution Control and Ecological Security, 1239 Siping Road, Shanghai 200092, China; State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
⁶ Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China; Institute of Biosciences, Freiberg University of Mining and Technology, Freiberg 09599, Germany.

PMID: 31425976
DOI: 10.1016/j.scitotenv.2019.133926

Abstract

Being able to simultaneously reduce and adsorb highly toxic Cr(VI) from bodies of water would provide a significant advance in the treatment of water pollution. Herein, we report on the design of an electroactive filter consisting of nanoscale polyaniline modified carbon nanotubes (PANI-CNT). In an electric field, both Cr(VI) reduction kinetics and Cr(III) sorption capacity were enhanced as the flow rate and voltage increased. At pH 7, Cr(VI) removal efficiency increased from 29.3% at 0 V to 70.2% at 2.5 V. This can be ascribed to superior electrical conductivity, more available active sites and limited pore size of the PANI-CNT filter, further boosted by the flow-through operation. Due to convection-enhanced mass transport, the proposed continuous-flow PANI-CNT filter demonstrated an evidently enhanced kinetic process when compared to conventional batch system. Various advanced assessments and density functional theory calculations verified the essential role of the electric field during Cr(VI) removal. Scanning transmission electron microscopy (STEM) examinations showed that the Cr was mainly sequestered by the PANI. It was also confirmed that an exhausted PANI-CNT filter can be regenerated by chemical washing with an HCl solution. Experiments with actual Cr(VI)-contaminated electroplating wastewater further verified the effectiveness of the system, with complete Cr(VI) transformation and a 50% Cr_total removal efficiency at 2.5 V with a flow rate of 3 mL/min. This study provides new insights into practical continuous-flow solutions to the effective removal of highly toxic Cr(VI).

Keywords: Carbon nanotubes; Cr(VI); Detoxification; Electroactive filter; Polyaniline; Sequestration.