Utilization of sky fruit husk agricultural waste to produce high quality activated carbon for the herbicide bentazon adsorption

The present study utilized an agricultural low cost biomass sky fruit husk for the preparation of activated carbon by chemical activation with orthophosphoric acid (H3PO4) and later characterized by N2 adsorption-desorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Batch adsorption process was followed in order to evaluate the potentiality of the prepared activated carbon having BET surface area of 1211.57 m2/g for the removal of anionic herbicide bentazon from aqueous solution. The effects of initial concentration, contact time and pH has been studied. The adsorption study indicates that the adsorption data followed the Freundlich model better than the Langmuir which suggested the heterogeneous nature of the activated carbon surface. The monolayer maximum adsorption capacity of the sky fruit husk activated carbon (SFHAC) was found to be 166.67 mg/g. Kinetic data fitted better to the pseudo-second order model and intraparticle diffusion phenomenon indicated more than one process is regulating the adsorption process. The thermodynamic parameters associated with the adsorption process, standard free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were also determined at different temperatures and adsorption process was found to be endothermic in nature.