High adsorption capacity of nitrobenzene from aqueous solution using activated carbons prepared from vegetable waste

Abstract

AbstractThe present study reports the preparation of chemically activated carbons (PAC and ZAC) from apricot stones using phosphoric acid and zinc chloride, respectively. The potential use of the prepared carbons, as adsorbents, and the effect of chemical activation on the surface properties and adsorptive mechanism of nitrobenzene (NB) were investigated. The physicochemical properties of the obtained materials were characterized by Nitrogen adsorption–desorption isotherms, Scanning Electron Microscope, FTIR Spectroscopy, EDX analysis, Boehm titration, and pH of zero charge. The results show that the prepared samples present high apparent surface areas (1,382 and 1,111 m2/g for PAC and ZAC, respectively) and pores volumes with the presence of various functional groups. It was found that pseudo‐second model was the most suitable for the fitting of the experimental kinetic data and the intraparticle diffusion was not the unique rate‐controlling stage. The adsorption isotherms were well described by the Langmuir and the Freundlich models. According to the Langmuir model, the maximum adsorption capacity of PAC and ZAC were about 476.2 and 490.2 mg/g, respectively. The thermodynamic parameters showed the spontaneity, the exothermic nature, and the decrease in the randomness of the adsorption of nitrobenzene. Chemical regeneration showed that the prepared samples could be used for four time desorption–adsorption cycles with good efficiency for NB removal, indicating that the prepared carbons could be used as a low‐cost alternative to commercial activated carbon for the removal of nitrobenzene from wastewater.