Synthesis of Cr(VI)-imprinted poly(4-vinyl pyridine-co-hydroxyethyl methacrylate) particles: its adsorption propensity to Cr(VI)

The aim of this study is to prepare ion-imprinted polymers, which can be used for the selective removal of Cr(VI) anions from aqueous media. 4-Vinyl pyridine (4-VP) was used as functional monomer. The Cr(VI)-imprinted poly(4-vinyl pyridine-co-2-hydroxyethyl methacrylate), poly(VP-HEMA), particles were prepared by bulk polymerization. The Cr(VI)-imprinted polymer particles were grained from the bulk polymer, and the template ions (i.e., Cr(VI)) were removed using thiourea (0.5%, v/v) in 0.5M HCl. The Cr(VI)-imprinted polymer contained 21.4 μmol 4-VP/g polymers. The specific surface area of the IIP2 particles was found to be 34.5m(2)/g (size range of 75-150 μm), and the swelling ratio was about to 108%. The effect of initial concentration of Cr(VI) anions, the adsorption rate and the pH of the medium on adsorption capacity of Cr(VI)-imprinting polymer were studied. The maximum experimental adsorption capacity was 3.31 mmol Cr(VI)/g polymer. Under competitive condition, the adsorption capacity of Cr(VI)-imprinted particles for Cr(VI) is 13.8 and 11.7 folds greater than that of the Cr(III) and Ni(II) ions, respectively. The first- and second order kinetics models were estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. The Langmuir adsorption isotherm model was well described the Cr(VI)-imprinted system and the maximum adsorption capacity (Q(max)) was found to be 3.42 mmol/g. Moreover, the reusability of the poly(VP-HEMA) particles was tested for several times and no significant loss in adsorption capacity was observed.     

Effect of an External Magnetic Field on the Kα and Kβ x-Ray Emission Lines of the 3d Transition Metals

Abstract

The effect of an external magnetic field on the K shell energy shift (ΔE), FWHM (Wi), asymmetry index, and Kβ/Kα intensity ratio for diamagnetic (Cu and Zn), paramagnetic (V and Mn), ferromagnetic (Fe, Co and Ni), and antiferromagnetic (Cr) elements have been investigated using Cd-109 point source in the external magnetic field intensities 0.6 T and 1.2 T. The K x-rays from different targets were detected using a high resolution Si(Li) semiconductor detector. An accurate analytic representation of each line was obtained by a fit to a Gaussian. For B = 0, the measured Kβ/Kα intensity ratios were compared with the experimental and theoretical data in the literature. The results show that the atomic parameters can change when the irradiation is conducted in a magnetic field.