Competition Adsorption, Equilibrium, Kinetic, and Thermodynamic Studied over La(III)-loaded Active Carbons for Dibenzothiophene Removal

Abstract

La(III)/AC adsorbents were prepared by ultrasonic impregnation. The optimal preparation conditions of La(III)/AC were studied by calcination temperatures and La-loaded amount. Competition adsorption desulfurization from aromatics and adsorption mechanism were investigated onto La(III)/AC. Benzene, methylbenzene and naphthalene were selected to explore adsorption mechanism on dibenzothiophene (DBT). The results showed that La(III)/AC with calcination temperature for 803 K and La-loaded amount for 2 wt % possessed more effective performance of desulfurization. La(III) helped to enhance adsorptive capacity and selectivity, the effective degree of the aromatics over La(III)/AC for DBT removal decreased in the order naphthalene, methylbenzene and benzene. It was founded that the adsorption mechanism was mostly like to be π complex. Adsorption isotherms and kinetics were investigated, and the parameters were obtained. Results showed that adsorption isotherms could be well fitted by Langmuir model and maximum adsorption capacities increased with the temperature increasing. Adsorption kinetics could be represented by pseudo-second-order model, which suggested that chemical reaction along with electronic transfer and share seemed significant in the adsorption rate-controlling step. Adsorption process was spontaneous and exothermic.