Effective removal of fluoride and lead ions from aqueous solutions using water treatment residue and rice straw co-pyrolysis biochar composites
Kai Ning, Hansong Chen, Di Wang, Yun Hu, Yuting He, Shiyou Hao, Qingliang Cui, Zheng Shaocheng
Abstract
The coexistence of fluoride and lead in the waste water often leads to compound pollution, and finding effective and cost-effective solutions remains a significant issue. In this study, water treatment residues biochar (WTR-BC) was synthesized for the first time through the co-pyrolysis of water treatment residues and agricultural wastes to remove fluoride and lead. The results indicated that WTR-BC demonstrated remarkable efficacy in adsorbing fluoride and lead, achieving a maximum capacity of 15.2 mg/g and 83.8 mg/g, respectively. The adsorption mechanism adhered to a pseudo-second-order kinetic model, which illustrated that it was primarily driven by chemisorption. Moreover, X-ray photoelectron spectroscopy analysis indicated the formation of new complexes, F-Al and F-C with F on the WTR-BC surface, and X-ray absorption fine structure spectroscopy showed that the lead in the WTR-BC samples mainly existed as lead ferrihydrite (64.7%) and Pb(C2H3O2)2 (35.3%). These results revealed that the binding of lead and fluorides to the WTR-BC surface was attributed to Fe-O-Pb, C-O-Pb-O-C, and Al-F bond structures. The successful preparation of WTR-BC provides a new approach for the treatment of complex fluoride and lead pollution and holds promise as a novel material for environmental remediation. Furthermore, it broadens the scope of reuse possibilities for both WTR and agricultural wastes.