Performance Evaluation of Carbonized Vermiculite–Polycarbonate Nanofibrous Adsorbent for Congo Red Removal

Today, the removal of dyes as one of the most important pollutants in water resources using polymeric nanofibers and silicate-based materials has received a great deal of attention owing to their high specific surface area and active surface, respectively. This study aims to develop a polycarbonate (PC) nanofibrous adsorbent modified with 10 (%w/v) of carbonized vermiculite (CVMT) for elimination of Congo red (CR) from aqueous solutions. The field-emission scanning electron microscopy results show the electrospun nanofibrous sample with an average diameter of 235.8 nm. Prior to CVMT incorporation into PC nanofibers, the specific surface area of the sample is 6.4 m²/g and this value shows a slight increase up to 8.5 m²/g after the addition of CVMT. By adjusting the operational parameters such as pH of 3, adsorbent amount of 0.08 g, and CR initial concentration of 100 ppm, the adsorption capacity is about 42 mg/g. In the following, the pseudo-first-order kinetic equation besides the Freundlich model confirms that the adsorption process of CR is controlled by physisorption onto the heterogeneous surface of the nanofibrous adsorbent. Eventually, thermodynamic studies reveal the enthalpy of 14.92 kJ/mol and entropy of 0.055 kJ/mol, thereby suggesting endothermic and random adsorption process.