Supercritical water oxidation of nitrogen-containing organic compounds: process enhancement using isopropyl alcohol

摘要

The research in this thesis aimed to study efficiency and viability of supercritical water oxidation (SCWO) technology in treating diluted N,N-dimethylformamide (DMF), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and ammonia containing model wastewaters that were selected due to their hazard, wide usage in industry and having different degrees of refractoriness. udA lab-scale SCWO tubular reactor was operated to obtain necessary data to investigate the destruction of selected compounds at certain operating conditions in addition to studying the oxidation kinetics of DMF and DBU. Also, Isopropyl Alcohol was used to enhance the destruction of treating DMF, DBU and ammonia.udResults showed that temperature was the most influential variable where near complete TOC removal was obtained during DMF and DBU oxidation at 525oC and 250 bars. Temperatures of 400-550oC were not enough to achieve a significant destruction for ammonia. Organic concentrations and oxidant ratios also showed positive effects on the destruction of DMF, DBU and ammonia. IPA showed an essential role to destroy DMF, DBU and ammonia when used where a TOC removal of 99.4% and 99.2% was achieved for DMF and DBU respectively at 525oC and 250 bars and maximum TN removal of 97% was obtained at 550oC and 250 bars during ammonia oxidation. Also the presence of IPA reduced the activation energy of treated compounds where the values were 21.9 and 25.7 kJ/mol for DMF and DBU, respectively. Also it was found that oxygen has an influence and with oxygen order of 0.38 and 0.32 for DMF and DBU respectively.