We investigated the adsorption to granular activated carbon of two pharmaceuticals (carbamazepine and sildenafil citrate) and a personal-care product (methylparaben) in aqueous solution, characterized the carbon, and ...We investigated the adsorption to granular activated carbon of two pharmaceuticals (carbamazepine and sildenafil citrate) and a personal-care product (methylparaben) in aqueous solution, characterized the carbon, and evaluated its influence on the kinetics and adsorption equilibrium of the compounds under study. We adjusted data for the analysis of equilibrium to Langmuir and Freundlich models of adsorption isotherms and described adsorption rate using pseudo first- and second-order models;that same analysis was made on the basis of the behavior of the initial rate. In addition, we analyzed the potentiality of a nonlinear adjustment for studying kinetics and equilibrium of adsorption, an approach requiring neither knowledge of equilibrium conditions nor a-priori hypothetical suppositions regarding the order of reaction. The results indicated that the nonlinear model was capable of describing adsorption kinetic behavior, in order to determine concentrations adsorbed at equilibrium, adsorption rates of the system, maximum adsorption capacity, and global rate constant. Granular carbon exhibited an adsorption capacity for carbamazepine and methylparaben of ca. 323 mg/g and for sildenafil citrate of ca. 142 mg/g, though with slow adsorption kinetics characterized by average adsorption times of at least 168 h.展开更多
Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aq precursor, and characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Brunauer-E...Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aq precursor, and characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Brunauer-Emmett-Teller rn （BET）, temperature programmed reduction （Ha-TPR）, X-ray photoelectron spectroscopy （XPS） acidity measurements and elec conductivity. The catalytic activity was evaluated for volatile organic compounds （VOC） （ethanol, methyl ethyl ketone and tol oxidation. Additionally, catalysts were tested in particulate matter （PM） combustion. The characterization results indicated that Ce was in the form of Ce4＋ and Ce3＋, and Mn existed in the form of Mn4＋ and Mn3＋ on the surface of the Mn/AC sample and in the of Mn4＋ in the Ce/Mn/AC monolith. VOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent perforr compared with ceramic supported CeO2 （Ce/AC） and MnO, （Mn/AC） samples. The PM combustion was also higher on Ce/M monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, cond ity and the reducibility of the oxides.展开更多
文摘We investigated the adsorption to granular activated carbon of two pharmaceuticals (carbamazepine and sildenafil citrate) and a personal-care product (methylparaben) in aqueous solution, characterized the carbon, and evaluated its influence on the kinetics and adsorption equilibrium of the compounds under study. We adjusted data for the analysis of equilibrium to Langmuir and Freundlich models of adsorption isotherms and described adsorption rate using pseudo first- and second-order models;that same analysis was made on the basis of the behavior of the initial rate. In addition, we analyzed the potentiality of a nonlinear adjustment for studying kinetics and equilibrium of adsorption, an approach requiring neither knowledge of equilibrium conditions nor a-priori hypothetical suppositions regarding the order of reaction. The results indicated that the nonlinear model was capable of describing adsorption kinetic behavior, in order to determine concentrations adsorbed at equilibrium, adsorption rates of the system, maximum adsorption capacity, and global rate constant. Granular carbon exhibited an adsorption capacity for carbamazepine and methylparaben of ca. 323 mg/g and for sildenafil citrate of ca. 142 mg/g, though with slow adsorption kinetics characterized by average adsorption times of at least 168 h.
基金Project supported by National Scientific and Technical Research Council of Argentina(PIP 942)National Science and Technology Promotion Agency of Argentina(PICT 2012-2366)
文摘Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aq precursor, and characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Brunauer-Emmett-Teller rn （BET）, temperature programmed reduction （Ha-TPR）, X-ray photoelectron spectroscopy （XPS） acidity measurements and elec conductivity. The catalytic activity was evaluated for volatile organic compounds （VOC） （ethanol, methyl ethyl ketone and tol oxidation. Additionally, catalysts were tested in particulate matter （PM） combustion. The characterization results indicated that Ce was in the form of Ce4＋ and Ce3＋, and Mn existed in the form of Mn4＋ and Mn3＋ on the surface of the Mn/AC sample and in the of Mn4＋ in the Ce/Mn/AC monolith. VOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent perforr compared with ceramic supported CeO2 （Ce/AC） and MnO, （Mn/AC） samples. The PM combustion was also higher on Ce/M monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, cond ity and the reducibility of the oxides.
