title: Enhanced selectivity and capacity of clinoptilolite for Cd2+ removal from aqueous solutions by incorporation of magnetite nanoparticles and surface modification with cysteine.
abstract: In this study, magnetic zeolite (MZ) nanocomposite modified with cysteine was developed in order to enhance selectivity and capacity of clinoptilolite for cadmium ion. The prepared MZ nanocomposite is containing clinoptilolite and magnetite nanoparticles with weight ratio of 3:1. The synthesized nanocomposite was characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. Surface modification was confirmed by Fourier transform infrared spectrometer. Experiments were carried out to find the optimum conditions for modification of clinoptilolite and to investigate the effective parameters (pH, adsorbent dosage, contact time, and temperature) on the adsorption of Cd(2+) ion by modified clinoptilolite. The results showed enhanced selectivity of modified MZ in the presence of other naturally occurring cations (Na(+), K(+), Ca(2+) and Mg(2+)) and ammonium. Kinetic and equilibrium data were well fitted by a pseudo second-order and Langmuir model, respectively, with high correlation coefficients. The maximum adsorption capacities of the modified and non-modified clinoptilolite were found to be 20.0 mg/g and 5.2 mg/g, respectively. Thermodynamic parameters revealed that the adsorption process is spontaneous and endothermic under studied conditions.
authors.affiliation: Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Ghods Street, Enghelab Ave., Tehran, Iran E-mail: m.baghdadi@ut.ac.ir.
authors.forename: Masumeh
authors.initials: M
authors.lastname: Sharifi
authors.affiliation: Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Ghods Street, Enghelab Ave., Tehran, Iran E-mail: m.baghdadi@ut.ac.ir.
authors.forename: Majid
authors.initials: M
authors.lastname: Baghdadi
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds; D002104:Cadmium / Q000737:chemistry*; D002412:Cations; D003545:Cysteine / Q000737:chemistry*; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry*
chemical_list: D064751:Ammonium Compounds; D002412:Cations; D058185:Magnetite Nanoparticles; D014874:Water Pollutants, Chemical; D002104:Cadmium; C083175:clinoptilolite; D017641:Zeolites; D003545:Cysteine