Experimental investigation of the chemical reduction of nitrate ion in aqueous solution by Mg/Cu bimetallic particles

Abstract

Bimetallic particles have recently been used as a new means of contaminant reduction from water. Comparing with Fe0 and Mg0 alone, synthesized magnesium/copper (Mg/Cu) bimetallic particles have been determined to be potential and efficient agents for nitrate reduction from aqueous solutions. This study suggests that the reductive denitrification of nitrate by Mg/Cu bimetallic particles was dependent on a number of parameters including reductant dose, solution temperature, initial nitrate concentration and contact time. The 1% Mg/Cu (Cu loading of 1 wt.%) bimetallic particles removed the majority of the various nitrate concentrations tested (50, 100, 150, 200 and 300 mg/L) within a short period. The time required for the removal of 90.6% of the NO3 − from a 100-mg/L solution was about 20 min using 2 g/L bimetallic Mg/Cu at an initial solution pH of 6. The activation energy (E a) for the nitrate reduction by 1% Mg/Cu over the temperature range of 5–60 °C was 12.77 kJ/mol. The experimental results of the kinetic analysis from batch studies indicated that a higher initial nitrate concentration yielded a greater reaction rate constant and the denitrification rate increased with increasing 1% Mg/Cu dosage. The effects of mixing rate on the denitrification rate suggested that the reaction rate increases linearly at mixing rate <100 rpm and remained almost constant at rates over that.