Facile single-step synthesis of ZnFe2O4@biochar for synergistic adsorption and photo-Fenton degradation of RB and RBR binary dyes

Background

Biochar ferrite composites have attracted widespread interest in adsorption and photocatalysis.

Methods

ZnFe₂O₄@biochar (ZnFe₂O₄@C) photo-Fenton catalyst was synthesized by single-step pyrolysis strategy and characterized by SEM-EDS, FT-IR, XRD, BET, XPS, VSM, UV–vis DRS. The activity of ZnFe₂O₄@C was investigated via rhodamine B (RB) and reactive brilliant red X-3B (RBR) binary dyes photo-Fenton degradation.

Significant Findings

ZnFe₂O₄ was uniformly anchored on biochar and formed magnet-separable ZnFe₂O₄@C. ZnFe₂O₄@C exhibited synergistic adsorption and photo-Fenton activity. Combination ZnFe₂O₄ with biochar reduced the recombination rate of photo-generated carriers, and effectively accelerated the degradation of RB and RBR binary dyes. Under the optimal conditions, the removal efficiency of RB and RBR were both more than 99.00%, and the reaction rate constants were 0.1276 min^–1 and 0.0928 min^–1, respectively. The photo-generated holes and •OH were the main active species. The possible degradation pathways were involved in cleavage of C–N, N-de-ethylation, chromophore cleavage and benzene ring opening for RB, and deionization, cleavage of N = N and C–N, oxidization and benzene ring opening for RBR. This work provided a facile single-step synthesis strategy for ZnFe₂O₄@biochar photo-Fenton catalyst, which was magnet-separable, environment-friendly, pH adaptability-widely, and there was the potentiality for organic dyes wastewater treatment.