The Study On Wet Peroxide Oxidation Of Reactive Blue KN-R And The Analysis Of Mechanism

With the development of dyeindustry, dye wastewater pollution is becoming more and more serious. Dye wastewater contains lots kind of toxic and harmful substance, which makes dye wastewater pollution control become a focus of attention. Among all of dyes, anthraquinone dyes in second to azo dyes. Because anthraquinone dyes have a stable anthraquinone structer and are resistant to biodegradation, it lasts long time in the environment. Reactive Blue KN-R is one of anthraquinone dyes.To treat dyeing wastewater effectively, degradation of Reactive Blue KN-R by wet peroxide oxidation?WPO? was explored in high pressure reactor. The effects of H₂O₂ dosage, temperature, time, oxygen pressure and p H on the decoloratin rate and removal rate of TOC were investigated. It turns out that when the dosage of H₂O₂ is 20.4?L, temperature is 150 °C, time is 4 h, oxygen pressure is 0.5 Mpa and p H is 6.8, the best results can be obtained. The results indicated that under the optimum conditions, when the initial concentration of Reactive Blue KN-R was 200 mg/L, 100% of color reduction and 68.54% of TOC removal were achieved.The reaction kinetics were studied in the temperature range of 120-150 °C. The experimental data obeyed to the pseudo-first-order kinetic model. By calculation, the activation energy for the degradation of Reactive Blue KN-R was found to be 73.9 k J/mol?R2=0.96?. Some low-molecular-weight organic acid of degradation products were detected by gas chromatography/mass spectrometry?GC-MS?, like butanedioic acid, oxalic acid and phthalic acid. Because these low-molecular-weight organic acid are biodegradable, the Reactive Blue KN-R's biodegradability was greatly improved after WPO. Moreover, tert-butyl-alcohol as radical scavenger was used to study the radical mechanism and the result demonstrated that the existence of radical scavengers negatively affect the WPO of Reactive Blue KN-R. when the Reactive Blue KN-R reacted with tert-butyl alcohol at 150 °C and 0.5 Mpa oxygen pressure for 4 h, its absorbance measured at 596 nm increased from 0.00725 to 0.40696. Thus the hydroxyl radicals participated in the main degradation mechanisms and were primary responsible for the destruction of Reactive Blue KN-R.