Quaternary ammonium salts targeted regulate the surface charge distribution of activated carbon: A study of their binding modes and modification effects

Dingcheng Liang; Fengqin Yu; Keping Zhu; Zhijun Zhang; Jiawei Tang; Qiang Xie; Jinchang Liu; Fei Xie

doi:10.1016/j.envres.2022.114103

Quaternary ammonium salts targeted regulate the surface charge distribution of activated carbon: A study of their binding modes and modification effects

Environ Res. 2022 Nov;214(Pt 4):114103. doi: 10.1016/j.envres.2022.114103. Epub 2022 Aug 18.

Authors

Dingcheng Liang¹, Fengqin Yu², Keping Zhu², Zhijun Zhang², Jiawei Tang³, Qiang Xie², Jinchang Liu², Fei Xie⁴

Affiliations

¹ School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing, 100083, PR China. Electronic address: liangdc@cumtb.edu.cn.
² School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing, 100083, PR China.
³ State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, Beijing, 102299, PR China.
⁴ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui Province, 230029, PR China.

PMID: 35987375
DOI: 10.1016/j.envres.2022.114103

Abstract

Activated carbon (AC) is negatively charged in aqueous solution, which seriously restricts its application range. Quaternary ammonium salt as a common cationic surfactant was utilized to modify the surface charge distribution of materials. The evolution of the surface charge distribution of AC modified by benzalkonium chloride (BAC), diallyl dimethyl ammonium chloride (DDA) and 3-chloro-2-hydroxypropyl tri-methyl ammonium chloride (CTA) was investigated. Results showed that the surface charge of AC modified by CTA does not change significantly. BAC has a high molecular weight, low surface electrostatic potential and large steric hindrance due to its hydrophobic long-chain alkyl. The diffusion of BAC molecules from solution to AC changed its charge distribution. But these molecules were difficult to combine with AC surface, and most of them were adsorbed into the pores of AC to form aggregates, resulting in a significant reduction in the surface area. BAC modified AC could enhance the adsorption capacity of F^- in aqueous solution through electrostatic attraction, but the improvement effect was limited due to the reduction of surface area, and the maximum adsorption capacity was only increased from 1.18 to 3.31 mg/g. DDA has a small molecular weight and high surface electrostatic potential and easily binds to the surface of AC. Some CC bonds in DDA combined with the ionized hydrogen ions derived from phenolic hydroxyl groups in AC to form carbonium-ions. Then, they could react with AC to form ether bonds, causing DDA to be closely bonded with the surface of AC. DDA realizes the targeted regulation of the surface charge distribution of AC, it has little effect on the porous structure of AC. The modified AC still maintained strong adsorption capacity, and the maximum adsorption capacity for F^- was 54.98 mg/g. Meanwhile, a large number of zeolites were loaded on the modified AC and formed coating structures.

Keywords: Activated carbon; Binding mode; Modification effect; Quaternary ammonium salt; Surface charge distribution; Targeted regulation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Ammonium Chloride
Ammonium Compounds*
Charcoal / chemistry
Salts
Water / chemistry
Water Pollutants, Chemical* / chemistry

Substances

Ammonium Compounds
Salts
Water Pollutants, Chemical
Ammonium Chloride
Water
Charcoal