Treatment Of HNS Wastewater By Electrochemical Method

HNS waste water in production, is hard-decomposed waste water in industry, possesses features of being complicated, strong chroma, high poisonous, large quantity of macromolecule which is hard to be decomposed and high density of organics. As a new "green" technology, Electric chemistry employed electron as reagent to validate loss and gain reaction in which strong oxidation, hydroxyl radicals with no secondary pollution or vigorously active substances of oxidation were generated to deal with waste water filled with high density and poison. In this way, no extra chemical reagents are needed, other poisonous substances could not have much chance to show up in the process of degradation and it is called "friendly environment" technology for its advantage of low cost, high efficiency, little pollution and easy operation.The research design of three-dimensional electrode reactor with a titanium plate as a cathode, respectively study RuO2-IrO2-TiO2/Ti,RuO2-IrO2-SnO2-TiO2/Ti,IrO2-Ta2O5-TiO2/Ti and IrO2-Ta2O5-SnO2-TiO2/Ti four DSA anode material effect of degradation under the conditions of different voltage, and the reaction time, the electrode spacing, pH value, over anhydrous Na2SO4dosage, wastewater initial concentration to obtain the degradation of the optimal reaction conditions. On this basis, also studied the production wastewater degradation effects on HNS add to Fenton’s reagent. With DSA electrode on positive pole and pure titanium negative, conclusion was drawn from study of degradation of HNS waste water in production by analyzing potassium dichromate and method of multiple dilutions as follows:(1) Homemade three-dimensional electrode reactor processing HNS production wastewater, experimental conditions:wastewater initial concentration of6240mg·L-1, voltage8V, reaction time4h, the electrode spacing0.5cm, Na2SO4was0.375g·L-1, pH6,filler particles of glass beads and activated carbon mass ratio1:3, IrO2-Ta2O5-SnO2-TiO2/Ti the anode, the result was most efficient. At this point, COD removed22.67%, chroma removed98.13%.(2) Influences affecting COD and delete effort on chroma were arranged from top as distance between counter electrodes, density of waste water at the beginning, supporting electrode, ratio of stuffed electron. Under the condition of0.5cm gap between counter electrode, beginning density12480mg·L-1, ratio at1:2and anhydrous Na2SO4reached0.25g·L-1, the deletion rate of COD came to27.18%; under another condition with0.5cm gap between counter electrode, beginning density12480mg-L"1, ratio at1:3and anhydrous Na2SO4reached0.25g·L-1, the deletion of chroma could be up to98.67%. It made clear statement that deletion of chroma could be satisfying while that of COD is a little disappointment.(3) under the most suitable situation with COD finely deleted, added Fenton which is generated by7.5g·L-1Fe2+and0.01L H2O2in it so that rate of deletion of COD could get up to74.67%with rate of chroma could get up to99.25%. If same portion of Fenton were added without dealing with HNS waste water by electric chemistry treatment, rate of deletion of COD can’t be measured after the reaction and effort on deletion of chroma can also be a mess. It gave the judgment that use of Fenton improved generation and utilization of [·OH].(4) A large number of the intermediate products were generated in the process of electrochemical reaction, and small molecules such as straight-chain organic acid were directly oxidized into water and carbon dioxide with the generation of strong oxidizing active substances such as hydroxyl radicals [·OH]. However, the double bond of macromolecules were disconnected, then the macromolecules were oxidized into multi-nitro compounds, then were reduced into the amine compounds, and last were oxidized under the effect of hydroxylation [·OH].