The Study On The Pretreatment Of Nitrobenzene(TNT, DNT) Wastewater By Three-dimensional Electrode Reactor

The chemical composition of nitrobenzene wastewater is complicated, most of which belong to persistent organic matter with high concentration, so they are considered to be very harmful and lethal; most of pollutants have acute toxication, and they are difficult to be degraded. Therefore, they need to be pretreated to improve their biodegradability and attain the goal of biochemical treatment.In this paper, the nitrobenzene wastewater with the representative of TNT, DNT have been pretreated respectively by three-dimensional electrodes. These experiments employs Ti/SnO2+Sb2O3/β-PbO2 as anode, Ti plate as cathode and Sn-Sb-Ag/ceramic particles as the particle electrode. The process of degradation of nitrobenzene was studied preliminarily. In addition, the biodegradability of nitrobenzene wastewater was investigated after pretreatment.Ag and Sn-Sb-Ag catalyst were loaded respectively on the surface of ceramic particles as the particle electrode by impregnating and roasting method. The particle electrode were characterized by SEM,XRD and Cyclic voltammetry.The experiment indicates that Ag is distributed evenly at the surface of ceramic coated particle. Therefore Ag has good disperstiveness without gobbet. Besides, particle electrode has little effect on oxygen evolution over-potential for anode in different solution, and the electrocatalytic properties is improved a lot.Using the three-dimensional electrode reactor to preprocess TNT. The optimal parameter was obtained:the volume of Sn-Sb-Ag/ceramic particles is three times to ceramic particles, particle electrode and the surface of water is a consistent high degree, aeration are 0.06m3/h, the current density is 25mA/cm2, and electrochemical time is 60 min. The removal rate of TNT is more than 80%. Most of production are aniline and the biodegradability is improved greatly.Using the three-dimensional electrode reactor to preprocess practical DNT wastewater under the optimum reaction parameters. The current density is 30mA/cm2, initial pH is 5, and electrochemical time is 240min. Experiments show that CODCr of wastewater effluent reduced from 3058mg/L to 1170mg/L, and DNT concentration reduced from 538.01 mg/L to 71.19 mg/L, and chroma reduced from 12,500 times to 834 times. The removal rates is 61.74%,86.77%and 93.33%, respectively. The biodegradability also can be greatly improved, BOD5/CODCr increased from 0.08 to 0.37,became original 4.7 times. By validation of preliminary biochemical experiments, through the pretreatment by the three-dimensional electrode for 240min, wastewater can adapt to biochemical treatment, and then can enter thebiochemical system.