Influence of Surface Properties and Pore Structure of High Surface Activated Carbon on Adsorption Capacity of Dibenzothiophene

Abstract

Four activated carbons (ACs) with different properties were heat-treated at 600 °Cfor 3 h and the ACs before and after the treatment were characterized by nitrogen adsorption and XPS. The relationship between pore texture, surface chemistry and dibenzothiophene adsorption capacity was investigated. It is found that pore volume for the pore below 1nm and between 1.1-1.6 nm decreases and increases respectively, and mesopore volume increases after the heat treatment. The Brunauer- Emmett-Teller (BET) surface areas of the four samples remain almost the same after the treatment. The surface oxygen content decreases after the treatment. The adsorption isotherms can be better fitted by Freundlich equation than Langmuir equation, indicating that the adsorption sites on surface of the ACs is inhomogeneous. The dibenzothiophene adsorption capacity has a linear relationship with the pore volume of the pores in the range of 0.536-1.179 nm, indicating that micropore filling of dibenzothiophene is the dominant mechanism for dibenzothiophene adsorption. The adsorption capacity of dibenzothiophene for the pristine ACs is larger than that of the heat-treated ACs under the same pore volume for the pores in the range of 0.536-1.179 nm, indicating that surface oxygen functional groups favors the adsorption for dibenzothiophene.