Preparation of polystyrene-based activated carbon spheres with high surface area and their adsorption to dibenzothiophene

Polystyrene-based activated carbon spheres (PACSK) with high surface area were prepared through KOH activation. Effects of the carbonization temperature and the ratio of KOH to carbon spheres (CS) on the textural structure, hardness and yield of the resultant PACSK were studied, and their adsorption to dibenzothiophene (DBT) were investigated. The as-prepared PACSK exhibited a high surface area (up to 2022 m2/g), large total pore volume (≥ 0.78 cm3/g), superior mechanical hardness and high adsorption capacity (ca. 153 mg/g). With the increase of the KOH/CS ratio from 2:1 to 4:1, the surface area, total pore volume, volume of micropores, and volume of mesopores, increase, whereas the volume of small-micropores (< 0.8 nm) decreases from 0.36 to 0.31 cm3/g. The adsorption capacity has a good linear correlation with the volume of small-micropores rather than the surface area. In addition, the large quantity of acidic oxygen-containing groups of PACSK may also be responsible for their higher adsorption capacity and selectivity of DBT. The PACSK saturated by DBT can be regenerated by a washing process in a shaking bath or using ultrasonic with toluene at 80 °C.