Ultrafine CeO2-δ nanopowder, prepared by a simple and cost-effective self-propagating room temperature synthesis method (SPRT), showed high adsorption capability for removal of different azo dyes. Batch type of adsorption experiments with fixed initial pH value were conducted for the removal of Reactive Orange 16 (RO16), Methyl Orange (MO), and Mordant Blue 9 (MB9). The equilibrium adsorption data were evaluated using Freundlich and Langmuir isotherm models. The Langmuir model slightly better describes isotherm data for RO16 and MO, whereas the Freundlich model was found to best fit the isotherm data for MB9 over the whole concentration range. The maximum adsorption capacities, determined from isotherm data for MO, MB9, and RO16 were 113, 101, and 91 mg g(-1) respectively. The adsorption process follows the pseudo-second-order kinetic model indicating the coexistence of chemisorption and physisorption. The mechanism of azo dye adsorption is also discussed.
Polycrystalline -MnSe samples are investigated by Raman and photoluminescence spectroscopy. We assigned the first and the second order phonons in Raman spectra by a help of rigid ion model calculations. Several modes connected with spin system, whose width and frequencies depend on temperature, are assigned, too. Photoluminescence in -MnSe shows a steplike shift of emission bands below T N , in correlation with the antiferromagnetic spin-ordering in this material.
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