Elevated efficiency in tartrazine removal from wastewater through boron-doped biochar: enhanced adsorption and persulfate activation

Abstract Boron-doped biochar (B-BC) was synthesized by pyrolysis using solid waste of sorghum straw as raw material. The specific surface area of B-BC increased significantly by 2.38 times compared to that of pure BC. This enhancement allowed B-BC (0.3 g L−1) to achieve complete adsorption of 10 mg L−1 tartrazine (TTZ) within 40 min. Moreover, acidic conditions were more favorable for TTZ adsorption, achieving complete removal of TTZ in only 15 min at a pH of 3.0. Interestingly, the adsorption rate of TTZ by B-BC in the presence of 0.05 M Cl− was approximately 2.12 times higher than that in the absence of Cl−. When other background electrolytes were present, excluding PO4 3−, complete adsorption of TTZ could also be achieved within 60 min. Thermodynamic analysis and DFT calculations described the parameters of B-BC for TTZ adsorption, including $$\Delta {\text{G}}^{\Theta }$$ Δ G Θ (