Research On The Degradation Of Phenolic Wastewater By Persulfate Catalyzed By Nickel Based Catalyst

Phenolic wastewater has seriously polluted the environment and affected people's health.Recently,advanced oxidation technology based on persulfate has attracted wide attention due to its high efficiency.Virtually,compared with traditional Fenton reactions,this technique has higher oxidation capacity and wider pH range.Therefore,it is necessary to study an efficient catalyst to activate persulfate to oxide phenolic wastewater.In this study,the performance and mechanism of CaCO₃-NiO and Ag@LDO for the degradation of phenol by persulfate were investigated.In the CaCO₃-NiO/PS system,the degradation rate of phenol in 15 minutes arrived 92%,indicating that CaCO₃-NiO was an efficient catalyst.This study showed that CaCO₃-NiO/PS system exhibited the highest catalytic activity at the optimum conditions(the catalyst dosage was 1 g L^-1,the concentration of persulfate was 2 g L^-1 and initial pH was 11),In addition,after five cycles,the degradation rate of phenol can still reach 100%in 180 minutes,indicating that CaCO₃-NiO has a good reusability.Furthermore,the quenching experiments showed that the reaction in this system is not based on free radical.In addition,XPS characterization analysis showed that trivalent nickel was formed during the degradation process that lead to the oxidation.In the Ag@LDO/PS system,the degradation rate of phenol in 30minutes arrived 93%which is more effective than LDH to remove 91%phenol in 2 hours.Moreover,the study indicated that Only in a condition(the catalyst dosage was 1 g L^-1,the concentration of persulfate was 2 g L^-1 and initial pH was 11)can Ag@LDO/PS system showed greater efficiency.Moreover,the degradation rate drops great when pH is less than 7.In addition,after five cycles,the removal rate of phenol can still arrive 100%in 180 minutes,indicating that Ag@LDO has a good reusability.Moreover,the experiment in dark proved that photocatalysis was an important mechanism of phenol degradation.Accordingly,the quenching experiments showed that the reaction in this system is not based on free radical.Furthermore,the metal ions were hardly existed in the solution tested by ICP-AES and there were no intermediate products in this reaction by TOC and LC-MS.In this study,a non-free radical mechanism for phenol degradation by PS was proposed,which enriched the theory of heterogeneous catalysts activating PS to degrade phenolic wastewater.