Optimization and response surface modelling of activated carbon production from mahogany fruit husk for removal of chromium (VI) from aqueous solution

Abstract

The use of activated carbon (AC) from lignocellulosic wastes has gained a lot of research interest because of its great economic and environmental value. In this work, AC was prepared from mahogany fruit husk (MFH) via chemical activation with phosphoric acid and heat treatment. The relationships among the activation parameters H3PO4%, heating temperature, and holding time, and their effect on chromium (VI) removal, were investigated using the response surface method (RSM), following a central composite design (CCD). The optimized activation conditions resulted in a 92.3% Cr6+ removal efficiency for a 50 mg/L Cr6+ aqueous solution. The surface properties of the optimized MFHAC were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) spectroscopy, and nitrogen adsorption/desorption studies. The MFHAC prepared under the optimized conditions had a high surface area (SBET) of 1130 m2/g, with a well-developed porous structure. The equilibrium data of Cr6+ adsorption onto the MFHAC was best fit by the Langmuir isotherm model, while the adsorption kinetic data followed the pseudo-second order kinetic model. Hence, MFHAC proved to be an efficient technology for removing Cr6+ from simulated wastewater.