Adsorptive desulfurization of diesel with modified pig dung: experimental design with optimization, kinetics, isotherms and thermodynamics studies

Abstract

This study converted pig dung (PD) with garlic (Allium sativum) peel extract (GPE) to adsorbents (dried pig dung (DPD), activated carbon DPD (ACDPD) and GPE impregnated DPD (EDPD) and GPE impregnated ACDPD (EACDPD)), applied in the removal of Dibenzothiophene (DBT) from diesel. The four adsorbent samples (DPD, EDPD, ACDPD and EACDPD) were used for the removal of Dibenzothiophene (DBT) through batch desulfurization process at different experimental condition (dosage: 100 to 500 mg; time: 30 to 120 min and temperature: 25 to 50 °C) and appropriately characterized. EACDPD proved to be an adsorbent that can be employed for the desulfurization of diesel. The optimum equilibrium condition was achieved at 90 min for the removal of 67.76% of DBT applying a dosage of 178 mg, temperature of 45 °C and agitation of 260 rpm for the desulfurization process. The kinetic of the desulfurization process was best described by pseudo second order rate expression while the best isotherm model that best fitted the desulfurization data was Temkin model. The removal of DBT from diesel and its adsorption on EACDPD was an endothermic reaction with estimated change in enthalpy and entropy of 34.41 kJ/mol and 68.69 J/mol K respectively. Characterization showed transformation to the surface of the modified adsorbent (EACDPD) after chemical, thermal and impregnation from amorphous to plat like with improvement in micropore and mesopore of the adsorbent (EACDPD) while it was deduced that the presence of Mg and Zn in EACDPD enhance removal of DBT from diesel. This research is applicable in sustainable development goals (SDG) 7 and 11 respectively.