Treatment Of Azo Dye Wastewater By Iron-Carbon Microelectrolysis Combined With Fenton Reagent

Azo dyes are widely used in dyeing of fibers and silk fabrics.Their molecular structure is complex and they have biological toxicity.The common biological treatment is not effective.In this paper,reactive brilliant red X-3B was selected as the representative azo dye to study.In view of the high cost and poor degradation effect of traditional physical and chemical pretreatment methods,Fe/C micro-electrolysis combined with Fenton method was used to pretreat reactive brilliant red X-3B wastewater,and the combination of the two methods was explored.In order to combine the decolorization effect of Fe/C micro-electrolysis with the advantage of high COD removal rate of Fenton method.Three combination methods were studied:two-stage continuous treatment of Fe/C microelectrolysis-Fenton reagent,two-stage continuous treatment of Fenton method-Fe/C microelectrolysis,and coupling treatment of Fe/C microelectrolysis and Fenton reagent.The corresponding mechanism was explored and the following conclusions were drawn:?1?The decolorization rate and COD removal rate of azo dyes were 94.42% and 66.28% respectively under the optimal reaction conditions of Fe/C micro-electrolysis and Fenton method.The pH value of effluent was 6.11.In the following experiments,the reaction was slow under weak acidic conditions.With the decrease of pH value,the decolorization rate and COD removal rate were 99.19%,86.99%.?2?Fenton-Fe/C microelectrolysis process azo dyes continuously in two stages.It has nothing to do with the addition of activated carbon or not.Zero-valent iron loses electrons and is trapped by H⁺in strong acidic Fenton reaction solution to form double bonds of H₂ and H₂ reductive dyes.Electrons do not need to be transferred to organic matter through activated carbon conductors.Fe²⁺ formed by the anode is oxidized by dissolved oxygen,and a large number of new eco-Fe?OH?₃ flocs with strong adsorption are formed in the micro-electrolytic precipitation stage.The decolorization rate and COD removal rate are better.?3?The treatment of azo dyes by Fe/C microelectrolysis-Fenton reagent two-stage continuous treatment,Fenton method-Fe/C microelectrolysis two-stage continuous treatment,Fe/C microelectrolysis coupled with Fenton reagent for comparative analysis,Fe/C microelectrolysis coupled with Fenton reagent for treatment of reactive brilliant red X-3B effluent water quality is better than two-stage continuous treatment,and micro-electrolysis reaction consumes H⁺ As the pH value of the reaction solution increases,the Fenton chain reaction produces H⁺,and the pH value of the reaction solution decreases.The interaction of the two buffers keeps the pH value of the reaction solution between 2 and 4 for a long time,which is in the range of Fe/C microelectrolysis and Fenton reaction.