Reduction of Nitrate by Catalytic Bimetallic Particles
Date Issued
2006
Date
2006
Author(s)
Tseng, Wen-Yu
DOI
zh-TW
Abstract
Nitrate has no toxicity itself and is very stable at a low concentration. It is very easy to reduce into nitrite which hinders the function of blood carrying oxygen. The current technologies of denitrification are not economic and generate secondary brine wastes, and the efficiency of biological dentrification is influenced by the environment and the characteristic of microorganisms. Because of the above-mentioned defect our research focuses on the oxidation-reduction reaction to reduce nitrate. Zero-valent metal is easy available has powerful ability of reduction. Especially, zero-valent iron (ZVI) is widely used in the previous researches.
Previous researches indicated that it accelerates the efficiency of denitrification of ZVI by adding a few secondary metal. By the different electric potential of the two metals, they become a galvanic couple and accelerate the reaction. In this study, we add copper chloride into iron powder such that the iron powder will be coated by the metallic copper. This experiment proved that the efficiency of denitrification of iron powder coated by copper is faster than iron powder without copper.
Many researches described that the product of degradation of nitrate for the most part is ammonium. We need to raise the pH value and add a noble metal for forming nitrogen. Furthermore, we use HEPES to be buffer to prevent the pH value raising too fast.
The result shows that palladium is the best selection, and when pH is equal to 8.3 the selectivity of nitrogen is highest. The best ratio to iron, copper and palladium is 100%:0.5%:0.3%. Besides, when a noble metal existed, the rate of denitrification is slower that the rate without a noble metal, but it will react completely finally. The purpose above is preventing the medicament is over without arriving at the groundwater.
Subjects
硝酸鹽
零價鐵
催化性雙金屬
氮氣
nitrate
zero-valent iron
catalytic bimetal
nitrogen
SDGs
Type
thesis
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