title: Adsorption of Orange II dye in aqueous solution onto surfactant-coated zeolite: characterization, kinetic and thermodynamic studies.
abstract: Adsorption of anionic dye - Orange II - in aqueous solution onto hexadecyltrimethylammonium bromide (HDTMA)-coated zeolite (HCZ) reached 38.96mg/g compared with 8.13mg/g onto natural zeolite. Fourier Transform Infrared (FTIR), scanning electronic microscopy (SEM) and X-ray powder diffraction (XRD) data showed that HDTMA-coated zeolite developed surficial positive charges. The adsorption reaction fits the Freundlich isotherm (R(2)=0.93) and the value of 1/n was less than unity (=0.81) and suggest a multi-layer physi-sorption process. The kinetics of the adsorption is a pseudo-second-order model. The activation energy (Ea) of the reaction is +35.70kJ/mol to further support a physi-sorption process while the ΔH(o) (+82.79kJ/mol) is characteristic for an endothermic reaction. The ΔG(o) values of -2.33, -0.98 and -0.37kJ/mol at 25°C, 30°C and 35°C, respectively implied that the adsorption reaction was feasible and thermodynamically spontaneous. We proposed that both electrostatic interactions and partitioning process are involved in the adsorption mechanisms of Orange II dye onto HCZ.
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China; Fujian Key Laboratory of Pollution Control & Resource Reuse, Fuzhou 350007, Fujian Province, China.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Jin
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yu
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China; Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia. Electronic address: Zuliang.chen@unisa.edu.au.
authors.forename: Zuliang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Environmental Science and Engineering Programs, University of Northern British Columbia, Prince George, British Columbia V2N 4Z9, Canada; College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China.
authors.forename: Joselito M
authors.initials: JM
authors.lastname: Arocena
authors.affiliation: Environmental Science and Engineering Programs, University of Northern British Columbia, Prince George, British Columbia V2N 4Z9, Canada; College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China.
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Thring
keywords: Adsorption; HDTMA; Mechanisms; Orange II; Zeolite