Adsorptive Removal of Azo Dye New Coccine Using High-Performance Adsorbent-Based Polycation-Modified Nano-Alpha Alumina Particles

Abstract

The azo dyes new coccine (NCC) were successfully removed through the adsorption onto PVBTAC-modified α-Al2O3 particles. The optimal conditions of both the surface modification by PVBTAC adsorption and the NCC adsorption were thoroughly investigated. Formerly, polycations PVBTAC were adsorbed onto the nanosized α-Al2O3 particles at pH 8, NaCl 100 mM, with a contact time of 2 h, and initial concentration of 1000 ppm to modify the α-Al2O3 surface. Latterly, the NCC adsorptive removal was conducted at pH 8, NaCl 10 mM, α-Al2O3 adsorbent dosage of 3 mg mL−1, and a contact time of 45 min. Interestingly, the optimal pH of 8 potentially applies to treat real wastewater as the environmental pH range is often about 7–8. High removal efficiency and adsorption capacity of the NCC azo dyes were, respectively, found to be approximately 95% and 3.17 mg g−1 with an initial NCC concentration of 10 ppm. The NCC adsorption on the modified α-Al2O3 particles was well fitted with a Freundlich model isotherm. A pseudo-second kinetic was more suitable for the NCC adsorption on the PVBTAC-modified α-Al2O3 surface than a pseudo-first kinetic. The NCC adsorptive removal kinetic was also affirmed by the FT-IR spectra, based especially on the changes of functional group stretch vibrations of −SO3− group in the NCC molecules and −N+(CH3)3 group in the PVBTAC molecules. The high reusability of the α-Al2O3 particles was proved to be higher than 50% after four generation times.