Dynamic Model of Catalytic Denitrification of Nitrate over Pd-Cu Catalysts from Groundwater

Abstract

Groundwater polluted by nitrate contaminant is becoming a critical issue in China and worldwide. Catalytic denetrification of nitrate over Pd-Cu bimetallic catalyst shows a potential technique for the removal of nitrate from groundwater. In this study, a series of reduction experiments using γ-Al2O3 supported Pd-Cu particle catalysts in a batch slurry reactor were carried out. A tentative reaction mechanism and the dynamic model for catalytic nitrate reduction were discussed. It was found that nitrate consumption is based on the conventional Langmuir-Hinshelwood kinetic approach, assuming an irreversible bimolecular surface reaction between adsorbed reactant species to be the rate-controlling step. The equilibrium hydrogen adsorption constant Kads and the apparent surface reaction rate constant kapp were equal to 5.11×10-2 l/mg and 48.31mg/(l.gcat.min) at 293K temperature, respectively. The apparent activation energy for catalytic nitrate reduction, in the temperature range 280-298K, was found to be 36.8kJ/mol. The low value of activation energy obtained in this work confirms the very high effective and suitability of Pd-Cu catalysts for nitrate reduction.