Background: Fruiting bodies of two oyster mushroom (Pleurotus ostreatus and Pleurotus florida) species and their respective substrate samples cultivated and collected from the Mushroom Research, Production and Training Laboratory of the Haramaya University, Ethiopia, were analyzed for essential and non-essential metals, viz., Cu, Fe, Zn, Mn, Cd and Pb contents by flame atomic absorption spectrometry after digestion employing dry, wet and microwave digestion techniques. Concentrations of the analyzed metals were expressed on a dry weight basis (mg/kg). Results: The mean metal concentration (mg/kg in dry weight) in the mushroom and respective substrate samples, respectively; for Pleurotus ostreatus were: Cu (51.19, 48.97), Fe (220.87, 299.51), Zn (89.68, 62.55) and Mn (47.55, 58.32). The mean metal concentration (mg/kg in dry weight) in mushroom and the respective substrate samples, respectively, for Pleurotus florida were: Cu (53.56, 51.87), Fe (243.92, 265.23), Zn (95.26, 64.25) and Mn (41.29, 62.55). However, Cd and Pb was not detected in both mushroom and substrate samples. The bio-accumulation factor of the heavy metals was calculated and a highest accumulation of Cu and Zn from substrate was observed for all the analyzed mushrooms samples. The observed results were also compared with the reported results.

Phosphorous removal using efficient treatment approach such as adsorption is vital for the control of eutrophication. In this study, nanosized Fe-Al binary oxide sorbent was synthesized through a modified gel evaporation method and employed for adsorption of phosphate from aqueous system. The nanosorbent was characterized by x-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive x-ray spectroscopy (SEM/EDX), tunneling electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and flame atomic absorption spectroscopy (FAAS). Langmuir model showed the best fit to the experimental data with a maximum adsorption efficiency of 16.4 mg/g. Having all parameters optimized, it has been found that the nanosorbent exhibited 99.86% phosphate adsorption efficiency. The effect of co-existing anions on the adsorption of phosphate was also studied and no significant effect on the efficiency of the nanosorbent was observed due to competing ions such as fluoride. Desorbabilty of phosphate was investigated and found to be increased with increasing pH. The results of thermodynamic studies indicated that the process is spontaneous and endothermic. Both macroscopic and microscopic approaches were employed to predict the mechanism of phosphate adsorption on the Fe-Al binary oxide nanosorbent. Accordingly, the phosphate adsorption is presumed to occur via the replacement of surface hydroxyl groups by the phosphate species and formation of innersphere surface complexes at the water/oxide interface.

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Transition metals have a long a history in heterogeneous catalysis. Noble or precious transition metals have been widely used in this field. The advantage of noble and precious metal is...

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ABSTRACT. Ag-N-codoped zinc oxide nanoparticles were synthesized by a one-step impregnation of Ag in N-doped ZnO nanoparticles. The morphologies and structures of the as-synthesized nanomaterials were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis spectrophotometric techniques. Photocatalytic degradation of methyl red dye using synthesized photocatalysts was studied under solar as well as UV irradiations. Modified zinc oxide photocatalysts showed higher photocatalytic activity compared to pure zinc oxide both under solar as well as UV irradiations. Calcined zinc oxide shows better photocatalytic activity than commercial zinc oxide under both solar and UV irradiations. Highest catalytic activity of Ag-N co-doped zinc oxide (ANZ) among the undoped, Ag-doped and N-doped photocatalysts was attributed to the lower rate of recombination of the photogenerated electrons and holes as well as its lower band gap energy. Photocatalytic degradation of methyl red dye follows pseudo first order kinetics for all the nanoparticles so-obtained.

In the present work, nanocrystalline Fe-Al-Mn ternary oxide nanosorbent was synthesized via impregnation method. X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive x-ray spectroscopy (SEM/EDX), Brunauer-Emmett-Teller (BET) technique and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the assynthesized nanomaterial. The XRD results indicate the crystalline nature of the ternary oxide with a BET surface area of 49.53 m 2 g -1 . The optimum operating conditions to carry out sorption study such as pH, adsorbent dose, contact time, speed of agitation and initial phosphate concentration were found to be 3, 0.1 g, 16 h, 100 rpm and 30 ppm, respectively. Both Freundlich and Langmuir isotherm models fit the equilibrium data well with the latter model providing more fit to the experimental data. Kinetic data correlated well with the pseudo-secondorder and Elovich models suggesting chemisorptions as the prevailing mechanism of phosphate sorption onto the nanosorbent. Thermodynamic studies resulted negative ΔG indicating the spontaneity of the sorption process. The Fe-Al-Mn ternary nanocomposite sorbent showed a sorption capacity of 38.46 mg g -1 at pH 3. The sorption efficiency of the nanosorbent was found to be 99.5%.This adsorbent, with large sorption capacity and efficiency, is therefore a promising adsorbent for the removal of phosphate ions from aqueous systems.

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