Enhanced Adsorption of Xylenol Orange by CTAB-Functionalized Tomato-Derived Biochar: Mechanisms and Performance Evaluation

In this work, a tomato biochar composite modified with cetyltrimethylammonium bromide (CTAB@TBC) was successfully synthesized using an ethanol solution method. It was comprehensively characterized to evaluate its morphology (SEM), crystal structure (XRD), chemical bonding (FT-IR and Raman spectroscopy), surface area (BET analysis), and thermal stability (TGA). The adsorption performance of the composite for xylenol orange (XO) was subsequently evaluated in detail. The findings revealed that CTAB@TBC exhibited a maximum adsorption capacity of 150.59 mg/g for XO. Kinetic analysis indicated that the adsorption process conformed to a pseudo-second-order model, implying that chemisorption was the step limiting the rate. The Langmuir model accurately described the adsorption isotherm data, suggesting monolayer adsorption on a uniform surface. Thermodynamic evaluation further revealed a negative Gibbs free energy (ΔG) change, confirming the spontaneity of the adsorption process. In summary, the results suggest that CTAB@TBC is a highly effective adsorbent for eliminating dyes from wastewater and offers considerable promise for treating industrial effluents.