The environmental impact of untreated dye effluent is a concern due to potential mutagenic and allergic effects. This study aims to develop a cost-effective selenium-doped biochar as an adsorbent material to remove acid red (AR) and crystal violet (CV) dyes from water. Selenium nanoparticles (SeNPs) were produced using chemical and biological synthesis methods. The SEM, EDX, XRD, FTIR, and BET surface analysis methods were used to characterize the biochar and selenium-doped biochar (Se-AC and BSe-AC) samples. Surface modification with SeNPs resulted in an increase in surface area to 14.560m2/g for Se-AC and 85.456m2/g for BSe-AC. Different adsorption isotherms (Langmuir, Freundlich, and Temkin) and adsorption kinetic models (pseudo-firstorder, pseudo-secondorder, and intra-particle diffusion kinetics) were investigated to understand the adsorption patterns of biochar, Se-AC, and BSe-AC. The maximum adsorption capacities of biochar, Se-AC, and BSe-AC for AR and CV dye were found to be between 0.48mgg−1 and 7.51mgg−1, 2.31mgg−1 and 7.86mgg−1, and 6.88mgg−1 and 9.09mgg−1, respectively, at 313K. The obtained negative ΔG∘ indicates effective adsorption, while a positive ΔH∘ suggests an endothermic reaction for both dyes. BSe-AC is an eco-friendly alternative to biochar for removing AR and CV.
