Study on the recovery of spent nitric acid liquor containingformaldehyde and copper

• Main Authors: Che-Hung Ou, 歐哲宏
• Other Authors: Ming-Shean Chou
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/40634708264128044832

碩士 === 國立中山大學 === 環境工程研究所 === 102 === Water-borne nitrate and fertilizers make ground water heavily polluted by nitrate-N in addition to other associated pollutants. Recently, nitrate emission to water bodies are regulated by the government. A plant located in southern Taiwan produces a large quantity of a liquor containing nitrate, copper and formaldehyde from a process for silver recovery by copper addition. This paper reports results on the thermal destruction and H2O2 oxidation of formaldehyde for recovery of nitric acid from the waste liquor. Results indicate that with a destruction temperature of 700oC, 99% of COD (chemical oxygen demand) and formaldehyde in the original liquor could be achieved. With a temperature of 750oC, nearly 100% of the nitric acid in the tested liquor could be recovered. Around 80% of COD and formaldehyde in the liquor could be oxidized by the added H2O2 and the oxidation efficiency is not feasible for the recovery of the nitric acid in the liquid.