Adsorption of naphthalene onto high-surface-area nanoparticle loaded activated carbon by high performance liquid chromatography: response surface methodology, isotherm and kinetic study

Naphthalene removal from aqueous solution was investigated using zinc sulfide nanoparticle loaded activated carbon (ZnS-NPs-AC). The concentration of naphthalene was determined using high performance liquid chromatography (HPLC). The prepared ZnS-NPs-AC was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), particle size distribution (PSD), transmission electron microscopy (TEM) and BET surface area. A four-factor central composite design (CCD) combined with response surface modeling (RSM) was employed for the maximization of naphthalene adsorption in the batch mode of operation. Four independent variables viz. pH (1.0-9.0), initial naphthalene concentration (5-45 mg L-1), adsorbent dose (0.005-0.025 g) and contact time (5-25 min) were coded in a quadratic model to predict the response. The ZnS-NPs-AC was found to have a Langmuir monolayer adsorption capacity of 142.68 mg g(-1), while the pseudo-second-order kinetic model in combination with the Elovich equation described the said process (R-2 > 0.998) successfully.