The effect on the zeta potential of surface modified Philippine natural zeolites (SM-PNZ) for the adsorption of anionic solutions

Abstract

This study investigates the effect of surface modification on the surface charge of the natural zeolites (PNZ) from SAILE Industries in the Philippines by utilizing the zeta-potential technique. The SM-PNZ is prepared to be utilized in the adsorption of anionic aqueous solutions like gold cyanide [Au(CN)2-] solutions from gold extractive companies. The experiment was designed by converting natural zeolites into its Na-form and modified using cetyl trimethylammonium bromide (CTAB), a micelles-forming surfactant, with dosages equal to 100% and 200% of ECEC (external cationic exchange capacity) of the PNZ. Further characterization of the adsorbents by SEM shows a plate-like morphology. The zeta-potential of the SM-PNZ material shows a decreased negative surface compared with the unmodified PNZ. The percentage recovery of gold cyanide to the PNZ, SM-PNZ (100) and SM-PNZ (200) was 22%, 45% and 40% respectively. Surface modification has shown to improve the adsorption of the PNZ by decreasing the negative potential of the PNZ and increasing the affinity of the SM-PNZ to anionic solutions.