The adsorption properties of functionalization vetiver grass-based activated carbon: the simultaneous adsorption of phosphate and nitrate

Abstract

In this work, zirconium chloride octahydrate/CTAB/vetiver grass-activated carbon (ZR/CTAB/VGAC) was prepared from vetiver grass-activated carbon (VGAC), using zirconium chloride octahydrate (ZR) and cetyltrimethylammonium bromide (CTAB) as modifiers. The optimized conditions of the simultaneous phosphate and nitrate removal by ZR/CTAB/VGAC were discussed, including amount of adsorbent, initial concentration, pH, contact time, and temperature. The simultaneous removal efficiency of phosphate and nitrate was 96.50% and 51.17% under optimized conditions. The structural and morphology of ZR/CTAB/VGAC was investigated by using automatic volumetric adsorption analyzer (BET), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), and Fourier transform infrared spectroscopy (FTIR). It was found that the removal efficiencies of phosphate and nitrate were enhanced dramatically because ZR and CTAB were introduced on the surface of VGAC after modification. Moreover, the adsorption data fitted significantly well with Freundlich isotherm model. It was described well by pseudo-second-order kinetic model. Phosphate and nitrate adsorbed via chemisorption (ion exchange) by ZR, CTAB, and functional groups of the surface of ZR/CTAB/VGAC. Electrostatic adsorption of AC in ZR/CTAB/VGAC also played an important role in the adsorption process. ZR/CTAB/VGAC is an excellent adsorbent, which could be applied to remove nitrate and phosphate from wastewater.