Abstract
A novel polymeric composite resin, based on sepiolite and polyacrylonitrile (Sep/PAN), was synthesized and characterized using Fourier transform infrared spectrometry (FTIR), X-ray diffraction spectrometry (XRD), thermogravimetric analysis (TGA), and scanning electron microscope-energy dispersive X-ray (SEM-EDX). The thermal, morphological, and surface properties of the composite were improved by the presence of Sep. Furthermore, the prepared composite was applied for the removal of water hardness using both batch and column techniques. The effects of parameters, such as Sep content ratio, contact time, composite dosage, and hardness concentration, were studied. The Sep/PAN composite increased the removal efficiency of water hardness by 26% when compared to the pure Sep. For synthetic water samples, the Sep/PAN showed 100% removal efficiency within 60 min, with an optimum composite resin dosage of 3 g per 1 L of hard water and a corresponding experimental adsorption capacity of 316 mg/g. The adsorption results were observed to fit a pseudo-second-order kinetic model and a Freundlich adsorption isotherm model. Correspondingly, the column breakthrough capacity of the prepared composite resin was studied under various operating conditions. The composite performance for hardness removal from natural water samples, with a total hardness of 237-680 mg CaCO
3
/L, was assessed. The results demonstrated an efficiency range of 81-100%. These results suggested potential applications of the Sep/PAN composite for water softening, circumventing some of the difficulties in using clay alone while providing higher levels of efficiency.