Peach stones valorizated to high efficient biosorbent for hexavalent chromium removal from aqueous solution: adsorption kinetics, equilibrium and thermodynamic studies

Abstract

In the last years, much attention has been focused on the use of low-cost adsorbents for the removal of heavy metals from wastewater. Raw biosorbent waste is a cheap and environmentally friendly material that provides good cost-benefit for the industries that use it. The objective of this study is to improve the feasibility of raw local peach stones (RPS) waste for the removal of hexavalent chromium from aqueous solution. The characterization of this raw biomaterial has been performed using various analytical techniques such as FTIR, SEM and XRD. In batch adsorption experiments the adsorption parameters optimized were pH 2, adsorbent dose 4 g/L, equilibrium contact time 240 min, initial Cr (VI) concentration 30 mg/ L and temperature 30°C. The removal percentage of Cr(VI) was 97 % at pH 2.The adsorption equilibrium was well explained by the Freundlich isotherm and the process followed the pseudo-second order kinetics. Thermodynamic parameters specify the spontaneous and endothermic nature of biosorption process. Desorption study was carried out with NaOH (0.1, 0.5, and 1M) solutions. Investigations carried out proved that RPS is a good potential and ecofriendly biosorbent for the treatment of toxic hexavalent chromium in aqueous solutions.