Preparation, characterization, and desulfurization performance of the activated carbon prepared from mixed agro-wastes: an isothermal and kinetic study

Abstract

ABSTRACT The essential target of this work was to exploit some locally obtainable hard bio-wastes viz. date pits and pistachio shells, in preparing varioufigs activated carbons (ACs) via the optimised ZnCl2 and H3PO4 activation routes. After preparing ACs from an equal blend of the hard bio-waste, the best samples were identified for their BET surface area and pore volume, X-ray diffraction (×RD), Fourier Transform Infra-Red spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive X-ray (EDX). The ACZnCl2 exhibited a higher BET surface area (895.53 m2/g) than the ACH3PO4 (419.60 m2/g). The optimal ACs were implemented in the adsorptive elimination of dibenzothiophene (DBT) from model gasoline. The DBT trials were optimized by investigating the impact of the initial concentration of DBT (25–200 mg/L), ACs mass (0.05–0.40 g), temperature (0.0–60 °C), and working period (5.0–80 minutes). The highest elimination of DBT by ACZnCl2 reached 97.78% using 0.30 g of it at 40°C for 60 minutes employing 25 mL of 200 mg/L DBT, while ACH3PO4 revealed the superlative elimination of DBT (88.46%) utilising 0.35 g of it at 40°C for 70 minutes using 25 mL of 200 mg/L DBT. Besides the kinetics investigations, isothermal studies indicated that the Freundlich isotherm and the pseudo-2nd-order kinetic best described the DBT adsorption by the ACs more than the other models. In a batch process, the adsorption capacities of DBT by both ACZnCl2 and ACH3PO4 were 26.31 mg/g and 20.23 mg/g, respectively. The typical adsorption conditions for each adsorbent were employed to eliminate S- compounds from commercial gasoline and DBT in a fixed-bed system. In conclusion, the ACs above could be reutilised for 5 successive runs with an insignificant loss in their desulphurisation ability. They can thus be recommended for the desulfurization of fuels on an industrial scale.