Adsorption of Cr(VI) from aqueous solutions using novel activated carbon spheres derived from glucose and sodium dodecylbenzene sulfonate.

Cr(VI) is a common wastewater pollutant. Various adsorbents including carbon-based materials are used for the removal of Cr(VI) owing to their high adsorption capacity. Chemical activation is an effective method to increase the specific surface area of adsorbents and, thus, further improve their adsorption capacity. However, research on the adsorption and removal of Cr(VI) from aqueous solutions by chemically activated carbon spheres is limited. Here, glucose and sodium dodecylbenzene sulfonate were used to produce carbon spheres (CSs) via hydrothermal synthesis. Activated carbon spheres (ACSs) were then derived using KOH. The adsorption of Cr(VI) in solution by CS and ACS was investigated through batch experiments. The results indicate that the specific surface area of the ACS was 1491.21 m2 g-1, which was much higher than that of the CS. The adsorption kinetics of the sorbent was consistent with the pseudo-second-order kinetic model and the adsorption isotherm followed the Langmuir model. This indicated that the adsorption process of the ACS with respect to Cr(VI) was mainly via single molecular layer adsorption and chemisorption. In a 200 mg L-1 Cr(VI) solution, the maximum amount of Cr(VI) adsorbed by the ACS was 230.15 mg g-1, and some of these adsorbed Cr(VI) were reduced to Cr(III). These results show that ACSs have strong potential for application in the removal of Cr(VI) from aqueous solutions.