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Abstract: Calcined Mg/Al hydrotalcite (CH-Mg/Al) and calcined Mg/Al vanadate hydrotalcite (CHV-Mg/Al) were prepared and characterized. Adsorption kinetics, effect of pH, equilibrium isotherms and the selectivity of both absorbents were assessed. The removal mechanism was studied by XRD, XPS and FTIR. The results showed that there was no redox reaction during the adsorption process. The adsorption process of CH-Mg/Al was mainly anion exchange and adsorption on external surface of the layers. The adsorption capacity of CHV-Mg/Al was mainly caused by ion exchange. The calcined Mg/Al hydrotalcite showed wonderful vanadium (V) adsorption capacity. Using vanadate to synthesize hydrotalcite was unfavorable to removal of vanadium (V) from aqueous solution. CHV-Mg/Al had highly selectivity of vanadium (V) in the mixed solution of vanadate and dichromate. Calcined hydrotalcites material has potential application for the removal of vanadium (V) from aqueous solution. [Copyright &y& Elsevier]

A NbO x /Ce 0.75 Zr 0.25 O 2 (NbCZ) catalyst was synthesized by a citric acid-aided sol-gel method. It shows that above 80% NO x conversion and above 95% N 2 selectivity for the selective catalytic reduction of NO x by ammonia over this catalyst are achieved in the temperature range 200–450 °C. Based on the DRIFTS and kinetic studies over NbCZ and Ce 0.75 Zr 0.25 O 2 , the promotion mechanism by niobia loading was elucidated with an overall reaction pathway. Two different reaction routes, “L-H” mechanism via “NH 4 NO 3 + NO” at low temperatures (<200 °C) and “E-R” mechanism via “NH 2 + NO” at high temperatures (>350 °C), are presented. The niobia addition increases the surface acidity and promotes the formation of nitrates species at low temperatures. In this way, the reaction between the ads-NH 3 and nitrates species is accelerated to form NH 4 NO 3 intermediates, which then decompose to N 2 and H 2 O. The reaction of the ads-NH 3 species with gaseous NO x at high temperatures is also promoted due to the enhanced acidity and weakened thermal stability of nitrates after niobia loading. [ABSTRACT FROM AUTHOR]

Highlights: [•] Protons released from phenol electrochemical oxidation degradation form hydrogen. [•] Three stages were observed in phenol electrochemical oxidation degradation at 3V. [•] Each stages could be well described by the first order kinetic model. [•] ICE increased in first two stages while decreased dramatically in third stage. [•] Hydrogen yield improved in first stage but reduced in second stage. [ABSTRACT FROM AUTHOR]