Graft copolymerization of acrylamide onto coconut husk (CH), initiated by the ferrous ammonium sulfate/H 2 O 2 redox initiator system, was studied. To determine the optimum conditions of grafting, the effect of the concentrations of ferrous ammonium sulfate, the monomer, and H 2 O 2 and the time and temperature on percentage of the graft yield was studied. A new adsorbent media having a carboxylate functional group was synthesized by the surface modification of polymer-grafted coconut husk (PGCHOCOOH). The mechanism of graft polymerization and surface functionalization is proposed. The material exhibits a very high adsorption potential for Hg(II). The sorption of Hg(II) was found to be dependent on the contact time, concentration, pH, and temperature. Maximum removal of 99.4% with 2 g/L of the sorbent was observed at 125 mol L Ϫ1 Hg(II) concentration at pH 6.0. The slow step which determines the rate of exchange of Hg(II) ions is diffusion through the adsorbent particles. The diffusion coefficients, energy of activation, and entropy of activation were calculated and used to determine the theoretical behavior of the sorption process. The applicability of the Langmuir isotherm established the endothermic character of the adsorption. Acid regeneration was tried for several cycles with a view to recover the adsorbed metal ions and also to restore the sorbent to its original state. The adsorbent efficiency toward Hg(II) removal was tested using synthetic and chloralkali industry wastewaters.
Cu/TiO 2 thin films were deposited on glass substrates by reactive RF magnetron sputtering technique. Crystalline structure, surface morphology and electronic structure were studied using X-ray diffraction (XRD), field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Transmittance and absorptance of these films were characterized by UV-Vis spectroscopy. XRD patterns demonstrate that TiO 2 films deposited on glass substrate at 300°C are observed to be in pure anatase phase, whereas Cu/TiO 2 films are amorphous in nature at 300°C substrate temperature. The crystallinity of Cu/TiO 2 thin films decreases with increasing the dopant concentrations of Cu in TiO 2 films. XPS studies show that Cu is in ?2 oxidation state in all films. The optical band gap of Cu/TiO 2 films decreases from *3.3 to *2.0 eV with the increase in the copper concentration. Further, antimicrobial studies of Cu/TiO 2 films with *3.9 at.% Cu exhibit high transmittance and best antimicrobial activity against E. coli and S. aureus compared to other doped films.
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