Key factors and microscopic mechanisms controlling adsorption of cadmium by surface oxidized and aminated biochars

Ling Zhu; Lihong Tong; Nan Zhao; Xiang Wang; Xixiang Yang; Yizhong Lv

doi:10.1016/j.jhazmat.2019.121002

Key factors and microscopic mechanisms controlling adsorption of cadmium by surface oxidized and aminated biochars

J Hazard Mater. 2020 Jan 15:382:121002. doi: 10.1016/j.jhazmat.2019.121002. Epub 2019 Aug 17.

Authors

Ling Zhu¹, Lihong Tong², Nan Zhao³, Xiang Wang², Xixiang Yang⁴, Yizhong Lv⁵

Affiliations

¹ Key Laboratory of Conservation of Cultivated Land in North China, Ministry of Agriculture and Rural Affairs, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
² Key Laboratory of Conservation of Cultivated Land in North China, Ministry of Agriculture and Rural Affairs, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, China.
³ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
⁴ Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motook, Nishi-ku, Fukuoka, 819-0395, Japan.
⁵ Key Laboratory of Conservation of Cultivated Land in North China, Ministry of Agriculture and Rural Affairs, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, China. Electronic address: lyz@cau.edu.cn.

PMID: 31450208
DOI: 10.1016/j.jhazmat.2019.121002

Abstract

Modified biochar has great potential for adsorbing cadmium (Cd) in the aquatic environment, but the micro-immobilization mechanisms, driven by surface modifications, remain unclear. There has been no attempt to determine the key adsorption factors by integrating the numerous physiochemical indicators. In this study, surface oxidized biochar (OPBC) and surface aminated biochar (APBC) were prepared from porous biochar (PBC), and the Cd adsorption mechanisms by the modified biochars at the molecular and electronic scales were investigated. The adsorption capacity of APBC and OPBC for Cd was 23.54 and 19.04 mg g^-1, respectively, which was about three times higher than that of PBC. Macroscopically, physicochemical adsorption and intraparticle diffusion dominated the Cd adsorption, and surface properties, such as functional groups, were identified as key factors controlling adsorption. Microscopically, the adsorption of Cd mainly occurred in regions rich in π electrons, lone pair electrons and electron donor groups. The interaction between carboxyl and Cd dominated the adsorption performance of OPBC, while the Cd²⁺-π interaction was weakened by increasing the π electron electrostatic potential of aromatic rings. The lone pair electrons of the amino groups dominated the complexation of APBC with Cd, and the π electron electrostatic potential was almost unaffected.

Keywords: Cadmium; Microscopic adsorption mechanism; Porous biochar; Surface modification.

Publication types

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

MeSH terms

Adsorption
Amination
Amines / chemistry*
Cadmium / chemistry*
Charcoal / chemistry*
Oxidation-Reduction
Porosity
Surface Properties
Water Pollutants, Chemical / chemistry*

Substances

Amines
Water Pollutants, Chemical
biochar
Cadmium
Charcoal