Adsorptive removal of pollutants from industrial wastewater using mesoporous kaolin and kaolin/TiO2 nanoadsorbents.

Abstract

This study evaluated the adsorption of some pollutants and water quality indicator parameters from tannery wastewater using natural kaolin and synthesized kaolin-TiO2 nanocomposites. Natural kaolin, TiO2 and kaolin with TiO2 were characterized by X-ray diffraction (XRD), nitrogen gas adsorption-desorption Brunauer-Emmett- Teller (BET), Fourier Transform Infrared (FTIR), High Resolution Scanning Electron Microscopy (HRSEM), Energy Dispersive Spectroscopy (EDX), Selective Area Electron Diffraction (SAED) and High Resolution Transmission Electron Microscopy (HRTEM). The results of the characterization showed addition of TiO2 nanoparticles onto kaolin influenced the particle morphology, phase identification, surface area and functional groups. Batch adsorption techniques were investigated under the influence of contact time, adsorbent dosage and temperature. The adsorption trend of the parameters onto the nanoadsorbents was in the order kaolin/TiO2>kaolin. Kaolin/TiO2 nanoadsorbent with surface area of 53.80 m2/g showed high adsorption potentials for pollutants removal. Several adsorption isotherm and kinetic model were investigated. The adsorption data fitted well to pseudosecond order kinetic model. It was found that increase in temperature correspond to increase in the adsorption of the pollutants and other parameters, indicating that the system was endothermic in nature. From the results obtained, it can be concluded that the kaolin-TiO2 nanocomposites is a promising nanoadsorbent for the adsorption of toxic pollutants in tannery wastewater than kaolin alone.