Carboxyl and hydroxyl groups enhance ammonium adsorption capacity of iron (III) chloride and hydrochloric acid modified biochars

• Published in: Bioresource technology 2020-08, Vol.309 (C), p.123390-123390, Article 123390
• Main Authors: Wang, Siyuan, Ai, Shaoying, Nzediegwu, Christopher, Kwak, Jin-Hyeob, Islam, Md Shahinoor, Li, Yichun, Chang, Scott X.
• Format: Article
• Language: English
• Subjects: Adsorption; Adsorption mechanism; Ammonium; Ammonium Compounds; Biochar; Charcoal; Chemical modification; Electron shuttle; Hydrochloric Acid; Iron
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2020.123390

[Display omitted] •Wheat straw biochar was modified by FeCl3 and HCl.•Large surface area contributed abundant adsorption sites on modified biochars.•Ammonium adsorption by biochar was controlled by chemisorption.•Fe3+/Fe2+ redox coupling contributed to ammonium adsorption.•OCO groups in FeCl3 and HCl modified biochars enhanced ammonium adsorption. The effectiveness of the modification of wheat straw biochar using FeCl3 and HCl, alone or combined, on ammonium adsorption was evaluated using kinetic and isotherm models. The adsorption mechanisms were studied by comparative analysis of the surface properties of the biochars before and after ammonium adsorption. The results indicate that the modification methods enhanced the ammonium adsorption capacity by at least 14%, due to the increased OH and OCO functional groups and specific surface area, and increased Fe3+/Fe2+ redox coupling serving as an electron shuttle. It can be concluded that chemical modification of wheat straw biochars using FeCl3 and HCl increased the effectiveness of biochars for the treatment of ammonium-contaminated wastewater.