| Dye wastewater is a typical kind of bio-refractory wastewater with high concentration, chroma, complicated component and low degradability, the traditional wastewater treatment technique cannot meet the needs of discharge standard. Therefore, it has far-reaching significance to find an economical and applicable technique of wastewater treatment with high efficiency and investigate its reaction mechanism for the technique of dyeing wastewater treatment.In this dissertation, four typical dyestuffs, Direct Pink12B, Reactive Brilliant Orange X-GN, Reactive Brilliant Blue X-BR and Rhodamine B were chosen as research object. Experimental research has been done in degradation of simulative dyestuff wastewater with the adoption of iron-carbon micro-electrolysis and Fenton reaction in joint application. In this dissertation, there are four aspects studied:(1) The treatment of different simulative dyestuff wastewater using iron-carbon micro-electrolysis and Fenton reaction were investigated.(2) The degradation characteristics and reaction conditions of simulative dyestuff wastewater were studied particularly under combined process.(3) The degradation mechanism and pathways of pollutants using iron-carbon micro-electrolysis and Fenton reaction are also discussed.(4) The technological conditions of real dyestuff wastewater treatment were discussed experimentally with combined process.(1) According to the experimental results, iron-carbon method have an obvious effect on the treatment of dye wastewater. The best treatment conditions for simulated dye wastewater are as follows:for300mL direct red12B wastewater with the concentration of2g/L, the best pH, dosage of scrap iron, ratio of Fe/C and the reaction time are3,10g,1:1.1and90min respectively, COD removal rate is63.4%; for300mL reactive brilliant orange X-GN wastewater with the concentration of4g/L, the best pH, dosage of scrap iron, ratio of Fe/C and the reaction time are2,1Og,1:1.2and90min respectively, COD removal rate is62.3%; for300mL reactive brilliant blue X-BR wastewater with the concentration of4g/L, the best pH, dosage of scrap iron, ratio of Fe/C and the reaction time are2,10g,1:1.1and90min respectively, COD removal rate was55.4%; for300mL Rhodamine B wastewater with the concentration of2g/L, the best pH, dosage of scrap iron, ratio of Fe/C and the reaction time are3,10g,1:1.1 and90min respectively, COD removal rate is36.8%. For each dyestuff, the percentage of decolority reached up to80%.(2) The best conditions for simulated dye wastewater with combined treatment technology of iron-carbon micro-electrolysis and Fenton reaction are as follows:for300mL Direct Red12B wastewater under iron-carbon treatment process, the best pH, dosage of H2O2and reaction time were3,37mmol/L and30min respectively, COD removal rate and percentage of decolority are83.7%and93.1%; for300mL Reactive Brilliant Orange X-GN wastewater under iron-carbon treatment process, the best pH, dosage of H2O2and reaction time are3,34mmol/L and30min respectively, COD removal rate and percentage of decolority are84.8%and95.1%; for300mL Reactive Brilliant Blue X-BR wastewater under iron-carbon treatment process, the best pH, dosage of H2O2and reaction time are3,38mmol/L and30min respectively, COD removal rate and percentage of decolority are85.9%and95.2%; for300mL Rhodamine B wastewater under iron-carbon treatment process, the best pH, dosage of H2O2and reaction time are3,38mmol/L and30min respectively, COD removal rate and percentage of decolority are81.6%and91.2%.(3)The degradation pathways of Direct Pink12B, Reactive Brilliant Orange X-GN, Reactive Brilliant Blue X-BR and Rhodamine B dye wastewater with iron-carbon micro-electrolysis and Fenton oxidative degradation in joint application have been studied by using UV, IR and HPLC-MS Spectra analysis, the results revealed the oxidative degradation rule of azo, anthraquinone and Rhodamine dyestuff.With strong oxidizing property, various dyestuffs can be oxidized and degraded completely by formed hydroxyl radical in Fenton reaction. Regarding to azo dyestuff, groups with high density of electron cloud are attacked by hydroxyl radical firstly, especial for the groups nearby azobenzene lead to azo dyestuff decolour by breaking chromophore; then the groups which can be oxidated easily are attacked, such as benzene ring and naphthalene ring; triazine is degraded at last. Regarding to anthraquinone dyestuff, because of electron cloud density of anthraquinone is higher than benzene ring and triazine, at first hydroxyl radical attack the chromophore nearby anthraquinone, make it break and lead to decolouration; then attack the groups which is easy to oxidize, such as benzene ring and naphthalene ring; triazine is degraded finally. Regarding to Rhodamine dyestuff, firstly, hydroxyl radical attack the ethy on both sides of heterocycle lead to de-ethylation, ring cleavage and structural failure, it forms various aromatic acid; then hydroxyl radical attack aromatic ring to open-loop and degradation. After a series of reactions, each dyestuff finally mineralizate to inorganicThe acquisitions of this paper are mechanisms, characteristics and regularities in degradation process founded on simulative wastewater treatment and the best reaction conditions founded on real wastewater treatment under iron-carbon micro-electrolysis and Fenton reaction in joint application. The acquisitions which have great significance lead iron-carbon micro-electrolysis and Fenton reaction in joint application to high efficiency and economical treatment technique of printing and dyeing wastewater, supply experiment basement and theoretical guidance, provide reference to this kind of technique that act in process design and optimization of dyeing wastewater treatment.The innovations in this paper cover the following:first of all, the degradation characteristics and reaction conditions of simulative dyestuff wastewater were studied particularly under iron-carbon micro-electrolysis and Fenton reaction in joint application, it was known that the reaction rules and optimum conditional combinations of pollutants degradation with joint process and acquired a treatment technical method in joint application which have dyeing wastewater reach the standard. Secondly, it was the first time to use image analysis of UV、IR、HPLC-MS to inspect, analyse and judge the intermediates and end product which degraded from Direct Pink12B, Reactive Brilliant Orange X-GN, Reactive Brilliant Blue X-BR and Rhodamine B. In this manner, it greatly improve the reliability of results in analysis and determination, on this basis, with revealing degradation mechanism, inferring degradation pathway of dyestuffs, acquired the degradation rule of pollutants which degraded under iron-carbon micro-electrolysis and Fenton reaction in joint application. Studies supplied theoretical basis and technical route for exploring degradation of PAHs dyestuffs. Finally, base on real wastewater treated experiments under iron-carbon micro-electrolysis and Fenton reaction in joint application, the key problems aim to application in industrialization are discussed carefully and comprehensively and the base of developing industrialization about wastewater treatment technique was established. |
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