Abstract
Today, water pollution by polycyclic aromatic hydrocarbons (PAHs) has gained attention due to their widespread prevalence in the environment and the associated adverse health effects. Naphthalene must be removed from aquatic environments as one of the most significant and hazardous pollutants. The adsorption method is considered promising for eliminating various mineral and organic pollutants, regarded as economical and environmentally friendly. In this study, Organobentonite (OBt) was synthesized through the intercalation of cetyltrimethylammonium bromide (CTAB) as a cationic surfactant into Sodium Bentonite (SBt) with different cation exchange capacities (CEC). OBt and SBt were characterized by X-ray diffraction (XRD), Surface analysis, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) before and after the adsorption process. Various parameters, including CEC (0.5-2.0), contact time (0–90 minutes), and contaminant concentration, were investigated to understand adsorption behavior of naphthalene. After determining the equilibrium time, isotherm experiments were conducted. The results demonstrated that CTAB as a modifier enhances the adsorption capacity of OBt. Adsorption isotherms indicated that the partitioning mechanism predominantly governs the adsorption process and exhibited a better fit with the Freundlich isotherm model, with a correlation coefficient of determination (R2 > 0.97). The maximum adsorption of naphthalene was achieved at 2.0 CEC. A contact time of 15 minutes was identified as the optimal time to reach maximum adsorption capacity. The maximum adsorption capacity for Naphthalene on OBt was 14.05 mg/g, while for SBt, it was 5.22 mg/g. These findings indicate that modified bentonite can be employed as a suitable natural adsorbent for removing PAHs from aqueous solutions. This is due to its efficiency, simplicity, and cost-effectiveness compared to conventional methods.