Application of surfactant-modified zeolite-activated carbons as adsorbents to a semi-batch operation

Abstract

Modified zeolite-activated carbons (H-CL-CB1, H-CL-CB2) in a proportion of 50/50 w/w and 20/80 w/w were used for methylene blue removal from aqueous solutions under a semi-batch operation. Dye adsorption kinetic analysis was also studied for H-CL-CB1, H-CL-CB2, modified zeolite (H-CL), commercial activated carbon (CB), hematite (HM) and clinoptilolite (CL). Equilibrium isotherms and thermodynamic analysis of dye were studied for H-CL-CB1, H-CL-CB2, CB, CL, H-CL and HM under a batch operation at 20°C, 40°C and 60°C. The physical and chemical properties of all adsorbents were characterized through Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis and the point of zero charge. The maximum methylene blue removal (99% and 96%) on different modified zeolite-activated carbons (50/50 w/w and 20/80 w/w) was achieved after 57 and 130 min, respectively. Dye adsorption process onto H-CL and H-CL-CB1 (50/50 w/w) was found to be controlled by chemisorption while onto CB and H-CL-CB2 (20/80 w/w) by film diffusion. Isotherm studies have shown that dye adsorption data on CL, H-CL, H-CL-CB1 and H-CL-CB2 were best described by Freundlich isotherm while on HM and CB by Langmuir isotherm. According to thermodynamic study, the negative values of ∆G° indicate that dye adsorption process was favorable. The positive values of ∆H° indicate endothermic nature of adsorption. Zeolite-carbon adsorbents can be used as filters to remove organic compounds from wastewaters. © 2018 Desalination Publications. All rights reserved.