Study Of Acrylonitrile Wastewater In Catalytic Wet Peroxide Oxidation

The wastewater of acrylonitrile(AN) producting process contains toxic substances, such as acetonitrile, hydrocyanic acid, acrylonitrile polymer, ammonium sulphate and so on. So the acrylonitrile wastewater has so many characteristics e.g. complicated composition, poor biodegradability, high toxicity, etc. And the ammonia in water increased after the biochemical reaction of organic nitriles, that increases eutrophication hazards. If the water is untreated or treated wastewater did not meet standard discharged into the natural environment directly, it will destroy the natural environment and threaten human health. Therefore, how to treat the acrylonitrile wastewater effectively and make it achieve standards have become one of the most important issues to be solved.Catalytic wet peroxide oxidation(CWPO) is based on wet air oxidation(WAO) conditions(high temperature, 398 ~ 623 K, high pressure, 0.5 ~ 20 Mpa) and adding catalyst, in order to reduce the harsh reaction conditions, to improve the reaction effceincy, etc.This experiment bases on previous wet oxidation technology, we use catalytic wet oxidation technology and take hydrogen peroxide as the oxidant, add single and composite catalysts, respectively. Then study the catalytic reaction mechanism and the Reaction characteristics of wet oxidation in acrylonitrile wastewater. In this paper, the waste water is analog acrylonitrile wastewater, which contains 4000 mg/L acrylonitrile, COD of 8766.5 mg/L, TOC of 3088.2 mg/L. OE, reaction temperature, reaction time and catalyst dose and other factors on COD, TOC and acrylonitrile removal rate are inspected. Then we determine the order of catalytic wet oxidation factors by orthogonal experiment. Finally, the reaction kinetics and apparent activation energy is studied.In this experiment, we choose Cu2+ as the single homogeneous catalyst, and the proportion of composite catalyst is Cu2+:Ni2+:Fe3+:Zn2+=1:1:2:1.In the single catalytic experiments,(1) OE is 0.8, reaction temperature is 523 K and catalyst dose is 250 mg/L, when reaction time between 1 min to 9 min, the removal of COD, TOC, AN rocket from 91.66%, 91.86%, 89.28% to 97.23%, 97.78% and 96.07%, respectively;(2) reaction temperature is 523 K, reaction time is 9 min, catalyst dose is 250 mg/L, when OE rises from 0 to 0.8, the removal of COD, TOC, AN rocket from 90.26%, 90.28%, 87.05% to 97.23%, 97.78% and 96.07%, respectively;(3) OE is 0.8, reaction time is 7 min, catalyst dose is 250 mg/L, when reaction temperature increases from 483 K to 523 K, the removal of COD, TOC, AN rocket from 94.52%, 94.86%, 92.42% to 96.88%, 97.02%, 94.90%, respectively;(4) OE is 0.8, reaction time is 7min, reaction temperature is 523 K, catalyst dose aggrandizes to 250 mg/L, three indexes ascent from initial 75.6%, 77.2%, 69.5% to 97.23%, 97.78% and 96.07% as the maximum value.In the complex catalytic experiments, the removal of COD, TOC and AN are higher than in the single catalytic experiments, and also rise smoothly. So the complex catalyst is more stable than the single catalyst.The order of wet oxidation factors is determined in the orthogonal experiment: reaction temperature> reaction time> peroxide amount > catalyst dose. Reaction kinetics study concluded that: single catalytic experiments and complex catalytic experiments conform to secondary dynamics; The apparent activation energy of single catalytic COD, TOC and AN removal experiments is 37.74 kJ/mol, 61.24 kJ/mol and 53.09 kJ/mol, respectively, and 30.60 kJ/L of complex catalytic COD removal experiment. The results proved that the effect of the composite catalyst is better than single catalyst and the reaction is easier.