Study On Treatment Of Reactive Black 5 Dye Wastewater By Persulfate Catalyzed By Iron-carbon Micro-electrolytic Filler

With the continuous progress of synthetic dye technology,more and more dyes that are resistant to photolysis,biodegradation,and oxidation are used.Conventional biological treatment processes are usually difficult to meet the requirements,and there is an urgent need to find more efficient dye wastewater treatment technology.In recent years,advanced oxidation technology that uses persulfate（PDS）to produce sulfate radicals（SO₄·^-）has received widespread attention.At present,the exploration of efficient activation methods and the preparation of catalysts for the efficient and continuous activation of PDS have become research hotspots.Studies on the activation of PDS with iron-carbon microelectrolytic fillers as heterogeneous catalysts are still rarely reported.In this study,regular iron-carbon microelectrolytic filler（Fe/C-MEF）with rich pore structure was prepared and used as a heterogeneous catalyst to activate PDS to degrade azo dye wastewater.Scanning electron microscope（SEM）and energy spectrometer（EDS）were used to characterize Fe/C-MEF.The study compared the effects of aeration and agitation on the degradation of RB5 dye by PDS activated by Fe/C-MEF.The efficiency of Fe/C-MEF to activate PDS to degrade RB5 dye was evaluated,and the effects of three initial conditions of PDS concentration,Fe/C-MEF dosage and initial pH of raw water on the degradation of RB5 by Fe/C-MEF/PDS system were investigated,To explore the effect of the presence of inorganic salt anions on the degradation of RB5.The UV-Vis spectrum change and solution color change of RB5 dye wastewater degraded by Fe/C-MEF/PDS system were investigated.Through the free radical quenching experiment,the free radicals that played a major role in the degradation process of RB5 were explored.The main mechanism of Fe/C-MEF/PDS system degradation of RB5 dye wastewater was analyzed.Finally,the stability of Fe/C-MEF recycling was investigated.The main research conclusions are as follows:（1）The optimized Fe/C-MEF preparation conditions were obtained,that is,Fe/C mass ratio is1:1,kaolin content was 30%,CMC additive content was 5%,and sintering temperature was 1000℃.The characterization results of Fe/C-MEF show that it has a rich pore structure and the Fe and C components required for the reaction are evenly distributed on the surface.（2）Comparing the two methods of agitation and aeration,it was concluded that when the action intensity of both reached a certain level,the decolorization rate and degradation rate of the RB5 dye degraded by the agitation were higher than the aeration.Moreover,Fe/C-MEF under aeration is more easily corroded and oxidized,which increases the loss of filler.Therefore,the stirring effect is more suitable as a way to accelerate the reaction,and the optimal paddle rotation speed is 100 r/min.（3）Compared with the degradation effects of the six systems on the RB5 dye,the Fe/C-MEF/PDS system showed better treatment effect,and the Fe/C-MEF filler after the reaction had a stable structure and was not easy to compact,which was beneficial to recycling.The optimized experimental conditions were obtained with PDS concentration of 15 mmol/L and Fe/C-MEF concentration of 24 g/L,and the initial pH range of raw water was 11 and below.The presence of inorganic salt anions has an effect on the degradation of RB5 in the system,and there are two fundamental reasons for its effect.First,it affects the pH value of the system to limit the release of metal ion catalyst;second,it consumes part of SO₄·^-to generate free radicals with lower activity.（4）The Fe/C-MEF/PDS system can quickly destroy the chromogenic structure of the RB5 dye molecule,and it is found that a new colored intermediate product is generated during the degradation process.The Fe/C-MEF/PDS system produced both SO₄·^-and OH·,but the degradation process of RB5 was mainly SO₄·^-oxidation.It is speculated that the degradation mechanism of RB5 by Fe/C-MEF/PDS system is mainly microelectrolysis reaction,Fe（Ⅱ）activated PDS,C activated PDS,and adsorption.Six cycles of experiments with Fe/C-MEF all achieved a decolorization rate of more than 87%for 1000 mg/L RB5,and the structure of Fe/C-MEF is stable,indicating that Fe/C-MEF can continuously catalyze PDS and has good stability.