Highly Dispersed Magnetite Nanoparticles on Biochar with Sulfonation Modification for Simultaneous Removal of Arsenite and Tetracycline from Aqueous Solutions: Performance and Mechanistic Insight
Zhendong Zhao, BiHan Zhu, Wenjun Zhou, Ming Zhang
Abstract
The remediation of combined pollution of heavy metals and antibiotics in an aqueous environment remains challenging. Through magnetite (Fe 3 O 4 ) dispersion followed by sulfonation modification, we report a novel bifunctional biochar-based composite (labeled Fe 3 O 4 @BC – SO 3 H) for simultaneous removal of arsenite (As(III)) and tetracycline (TC) in aqueous solutions. Batch experiments in single-solute systems show that Fe 3 O 4 @BC – SO 3 H exhibits faster kinetic and higher adsorption capacity than raw biochar, Fe 3 O 4, and magnetite-dispersed biochar (Fe 3 O 4 @BC), thus leading to enhanced removal efficiency for either As(III) or TC. More notably, Fe 3 O 4 @BC – SO 3 H can simultaneously remove above 85% of As(III) and TC compared with less than 50% removal of As(III) and TC by biochar, Fe 3 O 4, and Fe 3 O 4 @BC. Combining the spectroscopic analyses, the co-removal process of As(III) and TC indicates a unique mechanism with two-stage reactions, which involves As(III) redox transformation in the first stage and TC adsorption in the second stage. This study proposes a new strategy to design biochar-based composites for the decontamination of As(III) and TC. Overall, the excellent performance and stability of Fe 3 O 4 @BC – SO 3 H show its substantial potential as a low-cost, highly efficient, and eco-friendly material for the remediation of combined pollution in water.