Adsorption behavior of biochar pyrolyzed from barracuda grass for cadmium ions

Yan Shao; Zhiliang Chen; Zhonglei Zhang; Jun Pang; Yinyin Li; Jia Zhu; Gen Zhang; Xiaoshu Wang; Ming Chang; Lei Wang

doi:10.3389/fchem.2022.971540

Adsorption behavior of biochar pyrolyzed from barracuda grass for cadmium ions

Front Chem. 2022 Aug 17:10:971540. doi: 10.3389/fchem.2022.971540. eCollection 2022.

Authors

Yan Shao^{1

2}, Zhiliang Chen³, Zhonglei Zhang⁴, Jun Pang⁵, Yinyin Li⁶, Jia Zhu⁶, Gen Zhang⁷, Xiaoshu Wang⁶, Ming Chang⁸, Lei Wang⁶

Affiliations

¹ Institute for Thermal Power Engineering, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, China.
² Wuhan City Environment Protection Engineering Limited Company, Wuhan, China.
³ Guangdong Engineering Technology Research Center of Heavy Metal Pollution Control and Restoration in Farmland Soil, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, China.
⁴ China North Energy Conservation and Environment Protection Co, Ltd, Beijing, China.
⁵ College of Arts, Shandong Agricultural University, Taian, China.
⁶ School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen, China.
⁷ School of Ecology and Environment, Anhui Normal University, Wuhu, China.
⁸ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.

Abstract

This work investigated the removal of cadmium ions (Cd²⁺) by using biochar derived from Barracuda Grass. The biochars derived from the pyrolysis of roots (BGR), stems (BGS) and leaves (BGL) were characterized and their performance for cadmium adsorption was studied at varying parameters of temperature, time, and alkali (earth) metal concentrations. The maximum adsorption amount at equilibrium of BGR, BGS and BGL was determined experimentally as 8.38 mg/g, 42.12 mg/g, and 30.39 mg/g. Adsorption fitting results revealed that Cd2+ adsorbed on BGR and BGS preferred to be multilayer-covered, and BGL was more likely to have monolayer-covered functions. The kinetic data fitted well to the pseudo-second-order model (R ² > 0.99), revealing the adsorption process was a spontaneous monolayer chemisorption process. The results of alkaline (earth) metals leaching of biochar revealed that the inherent alkaline (earth) metals in biochar made inhibitory functions on the Cd²⁺ adsorption behavior by occupying the active sites. And in the process of wastewater treatment, the leaching of alkaline earth metals might enhance the complexation reaction between surface groups and Cd²⁺. This study provides a feasible strategy for the resource utilization of abundant hydrophytic plants in waste management.

Keywords: adsorption model; barracuda grass biochar; cadmium; mechanism; soluble cations.