Enhanced bacterial inactivation by activated carbon modified with nano-sized silver oxides: Performance and mechanism

Jianping Deng; Bing Li; Weizhao Yin; Huaitian Bu; Bo Yang; Ping Li; Xiangyu Zheng; Jinhua Wu

doi:10.1016/j.jenvman.2022.114884

Enhanced bacterial inactivation by activated carbon modified with nano-sized silver oxides: Performance and mechanism

J Environ Manage. 2022 Mar 11:311:114884. doi: 10.1016/j.jenvman.2022.114884. Online ahead of print.

Authors

Jianping Deng¹, Bing Li², Weizhao Yin³, Huaitian Bu⁴, Bo Yang⁵, Ping Li¹, Xiangyu Zheng¹, Jinhua Wu⁶

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
² School of Light Industry and Materials, Guangdong Polytechnic, Foshan, 528041, China.
³ School of Environment, Jinan University, Guangzhou, 510632, China.
⁴ SINTEF Industry, Department of Materials and Nanotechnology, Forskningsveien 1, 0373, Oslo, Norway.
⁵ School of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
⁶ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China. Electronic address: jinhuawu@scut.edu.cn.

PMID: 35287075
DOI: 10.1016/j.jenvman.2022.114884

Abstract

In this study, nano-sized silver oxides were loaded on activated carbon (nAg₂O/AC) through a facile impregnation-calcination method for enhanced bacterial inactivation from drinking water, in which Escherichia coli (E. coli) was used as target bacteria. XRD and SEM characterization confirmed that nano-sized Ag₂O particles (50-200 nm) were successfully prepared and uniformly distributed on the surfaces and pores of AC. Due to the structural reducing groups of AC, surface-bound Ag(I) was partially converted to Ag in the nAg₂O matrix and the resulted Ag could sterilize E. coli directly. More importantly, surface-bound Ag could catalyze O₂ and H₂O to generate reactive oxygen species (ROS) for oxidation sterilization, thus significantly enhanced the inactivation efficiency from 0.8 log₁₀ CFU/mL (nAg₂O control) and 0.2 log₁₀ CFU/mL (AC control) to 6.0 log₁₀ CFU/mL in the nAg₂O/AC system. The inactivation process was highly pH-dependent, and neutral pH was favorable for sterilization. A sterilization efficiency of 5.2 log₁₀ CFU/mL could still be achieved after 5 running cycles, indicating stable sterilization performance of nAg₂O/AC. In addition, the nAg₂O/AC also exhibited excellent renewability since a sterilization efficiency of 5.8 log₁₀ CFU/mL was obtained after nAg₂O being stripped and reloaded on the AC. These results demonstrated that nAg₂O-modified AC is an efficient material for sterilization in water treatment.

Keywords: Activated carbon; Modification; Silver oxide; Sterilization.