Green synthesize of CdS@Ben-Chitosan nanocomposite and its application for adsorption and photocatalysis of xylene

In the present study, a CdS@Ben–Chitosan nanocomposite was successfully synthesized via a green and facile approach and applied for the adsorption and photocatalytic degradation of xylene in aqueous solutions. The structural and surface properties of the synthesized nanocomposite were comprehensively characterized using XRD, SEM–EDX, FTIR, and BET–BJH analyses. The BET results revealed a mesoporous structure with a specific surface area of 128.3 m2 g⁻1 and an average pore diameter of 10 nm, which is favorable for adsorption and photocatalytic applications. Batch adsorption experiments indicated that the optimal pH for xylene removal was 6, which is consistent with the determined point of zero charge (pHpzc ≈ 6.1) of the nanocomposite. The adsorption performance was enhanced at lower initial xylene concentrations, with an optimum concentration of 5 mg L⁻1. Adsorption equilibrium was reached within 120 min, and the equilibrium data were best described by the Langmuir isotherm model, with a maximum adsorption capacity of approximately 60 mg g⁻1, suggesting monolayer adsorption on a homogeneous surface. Photocatalytic degradation experiments were conducted under UV irradiation (15 W), and the degradation efficiency increased with irradiation time, reaching a plateau after 120 min. Mineralization studies based on TOC analysis revealed that approximately 93% of xylene mineralization was achieved after 240 min of irradiation. Furthermore, the CdS@Ben–Chitosan nanocomposite exhibited good reusability and structural stability, maintaining high removal efficiency after multiple consecutive cycles. These findings indicate that the synthesized nanocomposite is a promising and efficient material for the removal of xylene from contaminated water through combined adsorption and photocatalytic processes.