Catalytical removal of nitrate and nitrite from drinking water: 1. Screening for hydrogenation catalysts and influence of reaction conditions on activity and selectivity

Abstract

The rising concentrations of nitrate in ground water make it necessary to use processes to remove nitrate from drinking water. Nitrate is removed at present either by physicochemical or biological processes. We describe here an efficient and rapid method to reduce nitrate and nitrite with hydrogen to nitrogen using supported precious metal catalysts. First, we screened for appropriate hydrogenation catalysts. Palladium on alumina was found to be favourable to reduce nitrite mainly to nitrogen. Ammonia as a by‐product is formed only in small amounts (98% nitrogen, 2% ammonia). Reduction of nitrate is possible by using bimetallic catalysts. We found the best results with a copper‐palladium bimetallic catalyst (nitrate removal activity of 3.13 mgNC₃‐/(min∗gcat), ammonia formation of 18%. Compared to the biological denitrification, the catalysts show a 30 times higher nitrate removal activity.

Keywords:

• Denitrification
• nitrate removal
• nitrite removal
• catalytic hydrogenation
• bimetallic catalysts.