Effect of pH and Temperature on the Catalytic Properties of Manganese dioxide

Manganese dioxide was studied for its catalytic activity under different experimental conditions such as pH (3 -10) and temperature (30 -70oC). Decomposition of hydrogen peroxide is used as an indicator reaction for the catalyst. The kinetics of the reaction was analyzed by first order equation and rate constants were determined from the slopes of the straight lines. It was observed from the experimental results that the decomposition rate constant was found to be dependent on pH and temperature. The high rate constants at high pH values for the decomposition reaction demonstrated the fact that negative surface sites are responsible for the decomposition of hydrogen peroxide. The same trend in the percent decomposition of hydrogen peroxide was observed while using NaNO3 as a background electrolyte. It was further noted that high temperature enhanced the catalytic activity of MnO2. Activation energy for the decomposition reaction at different pH was estimated from the slope of Arrhenius plot.

MURAD ALI ,NAILA KHALID ,KHALIDA AKHTAR ,