Study On The Treatment Of TNT Production Wastewater By Electrode-Fenton Method

TNT production wastewater is a kind of organic wastewater which is difficult to degrade and has large displacement. In this paper, the waste water from a certain military plant is desulfurized, and the removal rate of COD and total nitro compound is taken as an index,a self-designed cell was used as the generator, and then it is degraded by electric Fenton method as the pretreatment method.The main contents are as follows:The influence of graphite and titanium cathode materials on the COD removal rate of TNT production wastewater was studied. It was confirmed that the titanium cathode was used as the cathode, and the treatment effect of the system was stable.The best value of each influencing factor was determined by single factor experiment:U=6V, CFe²⁺ = 1.2mmol/L, nH₂O₂: nFe²⁺ = 20 :1, Na2SO4 =10g/L, pH=3,aeration intensity Q = 300L/h, D = 6cm , Reaction time t = 30min On the basis of single factor experiment, the fixed reaction conditions: pH=3,Na₂SO₄=10g/L, t = 30min, The orthogonal experiment of L16?45? was carried out,The primary and secondary factors influencing the water degradation were determined:plate spacing>Fe²⁺ the dosage>aeration intensity>nHZ₂O₂:nFe²⁺>U. According to the orthogonal results, the optimum combination of conditions was determined. The COD and total nitro compounds were 69.0225% and 97.12%, respectively.The kinetic model of degradation of TNT wastewater by electrode-Fenton method was established and the second-order kinetic model was obtained. The COD concentration was taken as the index, and the regression equation was:Ct=???Correlation coefficient R₂ = 0.9909It is presumed that the degradation process of nitro compounds in TNT production wastewater is: ?the nitro groups on the benzene ring are gradually reduced to hydroxyl groups:-NO₂?-NO?-NHOH?-NH₂ ?-OH.?The methyl group on the benzene containing aldehyde ring is gradually oxidized to hydroxyl group:-CH₃ ?-CHO ? -CH₂OH ? -COOH ? -OH.??benzene ring broken chain reaction,resulting in containing aldehyde, carboxyl and other long-chain intermediates, the final degradation of H₂O?CO₂ and small organic compounds and compounds.