Modification of activated carbon with a silane coupling agent under ultrasonic conditions for the advanced treatment of wastewater with dressing chemicals

Fresh activated carbon (FAC) was oxidised by nitric acid and then the silane coupling agent was grafted onto the surface of FAC under ultrasonic conditions to obtain modified activated carbon (MAC). The chemical oxygen demand was used as the main evaluation index in the wastewater. The effects of benzene, aniline, 2-mercaptobenzothiazole and methylene blue on the adsorption mechanism and performance of FAC prior and postmodification were investigated by different adsorption models. All of them fitted the Langmuir monomolecular adsorption model. The adsorption capacity of MAC was 1.07, 1.12, 1.56 and 0.62 times that of FAC, respectively, which had a better adsorption effect on hydrophobic organic compounds. The maximum adsorption capacity increased due to the existence of competitive adsorption in multicomponent absorption. Texture properties of activated carbon were characterised by scanning electron microscopy, Fourier Transform-infrared and Brunauer–Emmett–Teller theory, which show that the surface morphology became spongy, and that Si–O–C and Si–O infrared peaks appeared. In addition to the mesopore volume, the specific surface area, pore volume and micropore volume decreased slightly after the modification.