Study On Treatment Of Phenol Wastewater By Persulfate Enhanced Micro-electrolysis

Phenolic compounds are widely present in industrial wastewater and have strong toxicity,which will not only destroy the ecosystem,but also pose a threat to human health.Therefore,it is essential to seek efficient technology for the treatment of phenolic wastewater.Micro-electrolysis technology is a widely used technology in the field of water treatment,which degrades pollutants through primary batteries,redox reactions,coagulation and sedimentation.By activating persulfate（PDS）,free radicals（SO₄^-·）with strong oxidation ability can be generated,and then pollutants can be oxidized and degraded.Therefore,this study is based on the treatment of phenolic wastewater,self-made micro-electrolysis filler with rich pore structure,and constructed persulfate enhanced micro-electrolysis system,in order to provide technical support for phenolic wastewater treatment technology.The main conclusions are as follows:（1）The Fe/C micro-electrolysis filler was prepared by high temperature microporous activation technology.The effects of calcination temperature,Fe/C mass ratio,bentonite content and CMC content on the micro-electrolysis efficiency of the filler were investigated.The results showed that the removal rates of phenol and COD increased significantly with the increase of calcination temperature.With the increase of Fe/C mass ratio,bentonite content and CMC content,the removal rate first increased and then decreased.The preparation conditions were optimized by orthogonal experiment,and the optimal preparation conditions were determined as follows:calcination temperature 800℃,Fe/C mass ratio 2∶1,bentonite content 30%,CMC content 5%.Under these conditions,the removal rates of phenol and COD by the prepared fillers were 91.24%and 72.23%.Through characterization analysis,it was found that the surface of the filler had fine pore structure,indicating that the self-made filler had good micro-electrolysis efficiency and could efficiently degrade phenol wastewater.When the effect of reaction times on the micro-electrolysis efficiency of the filler was investigated,the removal rate of the filler was only reduced by about 10%after 5 times of reuse,indicating that the self-made filler has the ability to recycle.（2）The effects of reaction time,initial p H value and dosage of micro-electrolysis filler on phenol wastewater treatment were investigated.The results showed that with the increase of reaction time,the removal rates of phenol and COD gradually increased and finally stabilized.With the increase of initial p H value and micro-electrolysis filler dosage,the removal rate first increased and then decreased.The optimal reaction conditions were determined as follows:reaction time 120 min,initial p H value 3,and micro-electrolysis filler dosage 800 g/L.Under these conditions,the removal rates of phenol and COD were 91.27%and 72.76%.（3）The effects of reaction time,reaction temperature,initial p H value,PDS concentration and inorganic anions on the treatment effect were investigated in the persulfate-enhanced micro-electrolysis degradation of phenol system.It was found that with the increase of reaction time,the removal rates of phenol and COD gradually increased and finally stabilized.With the increase of reaction temperature,the removal rate increased significantly.With the increase of initial p H value,the removal rate increased first and then decreased and then increased.With the increase of PDS concentration,the removal rate increased first and then decreased.The optimal reaction conditions were determined as follows:reaction time 120 min,reaction temperature 65℃,initial p H 3,and PDS concentration 15 mmol/L.Under these conditions,the removal rates of phenol and COD were98.78%and 82.31%,respectively.It was found that NO₃^-,Cl^-,HCO₃^-and HPO₄^2-had different degrees of inhibition on the degradation of phenol wastewater,followed by NO₃^-<Cl^-<HCO₃^-<HPO₄^2-from small to large.By adding free radical quenching agent,it was found that the degradation of phenol was mainly through SO₄^-·strong oxidation and micro-electrolysis.（4）The response surface method was used to optimize the persulfate enhanced micro-electrolysis system.The analysis of variance and response surface analysis showed that R²>0.99,and the persulfate concentration,initial p H value and reaction temperature had significant effects on the response value.The optimal reaction conditions of the system were predicted by the response surface model:the concentration of persulfate was 15.81 mmol/L,the initial p H was 2.62,and the reaction temperature was 74.46℃.The verification results are basically consistent with the predicted values,indicating that the method is feasible for optimizing the process.The model can accurately simulate the persulfate enhanced micro-electrolysis degradation of phenol wastewater.