Hydrophobic modification of activated carbon and performance for oil-water separation

Abstract

Octadecyltrichlorosilane (OTS) and dodecanoic acid (LA) were used as modifiers to conduct hydrophobic modification of waste activated carbon by liquid impregnation and heat treatment. The non-polar organic carbon chains in siloxane and saturated fatty acid were grafted onto the surface of activated carbon by chemical bonds to improve its hydrophobic properties, and the blocked pores of activated carbon were recovered by thermal regeneration. The results show that the regenerated-hydrophobic activated carbon has a high specific surface area (834.75 m2·g-1), good hydrophobic performance (water contact angle is 135°) and acid/alkali resistance. The adsorption and separation efficiency of regenerated-hydrophobic activated carbon for toluene-in-water emulsion increases from 42.58% (unmodified activated carbon) to 92.07%. The purification and separation efficiency of water-in-toluene emulsion increases from 51.76% (unmodified activated carbon) to 91.44% by the hybrid filter membrane composed of regenerated-hydrophobic activated carbon and nylon organic filter membrane, and the separation efficiency is still higher than 91% after 10 cycles.

Keywords

• activated carbon
• hydrophobic modification
• regeneration
• specific surface area
• oil-water separation