Silica nanoparticles loaded on activated carbon for simultaneous removal of dichloromethane, trichloromethane, and carbon tetrachloride

The low efficiency of carbon derived from low-cost materials limits its industrial application as a low-cost adsorbent for the removal of contaminants from wastewaters. In this work, silica nanoparticles were loaded on activated carbon to produce an activated carbon/silica (AC/SiO2) composite. The product was characterized by means of thermogravimetric analyzer, scanning electron spectroscope, energy dispersive X-ray spectroscope, FTIR spectrophotometer, and X-ray diffraction. The AC/SiO2 was found to have a higher thermal stability than the AC. The XRD pattern of AC/SiO2 demonstrated that the AC was loaded with crystalline SiO2 as a tetragonal phase. For the removal of dichloromethane, chloroform and carbon tetrachloride, the operational parameters of contact time, initial concentrations and adsorbent dosage were optimized. The adsorption capacity increased with a decrease in the initial hydrocarbon concentrations. The experimental data were fitted to Langmuir, Freundlich, and Temkin isotherms, and pseudo-kinetic models. The Langmuir isotherm provided a better fit to the experimental data, assuming that adsorption takes place at specific homogenous sites within the adsorbent. The adsorption kinetics better fitted the pseudo-second order. The results of recycling tests demonstrate the excellent potential of adsorbents for pollutant removal. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.