title: A highly selective sorbent for removal of Cr(VI) from aqueous solutions based on Fe₃O₄/poly(methyl methacrylate) grafted Tragacanth gum nanocomposite: optimization by experimental design.
abstract: In this work, poly(methyl methacrylate) grafted Tragacanth gum modified Fe3O4 magnetic nanoparticles (P(MMA)-g-TG-MNs) were developed for the selective removal of Cr(VI) species from aqueous solutions in the presence of Cr(III). The sorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), a vibrating sample magnetometer (VSM), and thermo-gravimetric analysis (TGA). A screening study on operational variables was performed using a two-level full factorial design. Based on the analysis of variance (ANOVA) with 95% confidence limit, the significant variables were found. The central composite design (CCD) has also been employed for statistical modeling and analysis of the effects and interactions of significant variables dealing with the Cr(VI) uptake process by the developed sorbent. The predicted optimal conditions were situated at a pH of 5.5, contact time of 3.4 h, and 3.0 g L(-1) dose. The Langmuir, Freundlich, and Temkin isotherm models were used to describe the equilibrium sorption of Cr(VI) by the absorbent, and the Langmuir isotherm showed the best concordance as an equilibrium model. The adsorption process was followed by a pseudo-second-order kinetic model. Thermodynamic investigations showed that the biosorption process was spontaneous and exothermic.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Birjand, Birjand, Iran. Electronic address: ssadeghi@birjand.ac.ir.
authors.forename: Susan
authors.initials: S
authors.lastname: Sadeghi
authors.affiliation: Department of Chemistry, Faculty of Science, University of Birjand, Birjand, Iran.
authors.forename: Fatemeh Alavi
authors.initials: FA
authors.lastname: Rad
authors.affiliation: Department of Chemistry, Faculty of Science, University of Birjand, Birjand, Iran.
authors.forename: Ali Zeraatkar
authors.initials: AZ
authors.lastname: Moghaddam
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012107:Research Design; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D013818:Thermogravimetry; D014144:Tragacanth / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D058185:Magnetite Nanoparticles; D014874:Water Pollutants, Chemical; D014867:Water; D002857:Chromium; C074702:chromium hexavalent ion; D014144:Tragacanth; D019904:Polymethyl Methacrylate; D052203:Ferrosoferric Oxide
keywords: Chromium (VI); Experimental design; Modified magnetic nanoparticles; Removal; Tragacanth gum