Preparation Of Modified Biogas Residue Biochar And Degradation Of Phenol By Activated Persulfate

At present,the harm of phenol wastewater to ecological environment and human health gradually comes into people’s vision.Compared with other advanced persulfate-based oxidation technologies,biochar activated persulfate advanced oxidation technology has excellent performance in treating refractory organic pollutant phenol.It has the advantages of high degradation efficiency,environmental friendliness and no secondary pollution.Besides,biochar has rich modification conditions and a wide range of raw materials.Common agricultural and municipal wastes can be used as raw materials for biochar.Therefore,biochar activated persulfate advanced oxidation technology can not only achieve the degradation of organic pollutants,the use of raw materials can also realize the utilization of waste resources,to achieve the purpose of"win-win".Up to 200 million tons of biogas residue is produced in China every year.In order to reduce the current problem of difficult treatment of biogas residue,this paper selected rural manure biogas residue as raw material,prepared biogas residue biochar before and after modification by HCl modification through high temperature pyrolysis,and used SEM,TEM,XRD,Raman,BET,XPS and FTIR instruments to characterize and analyze the materials.Phenol and phenol containing coking wastewater were used as the target pollutants to investigate the degradation performance of activated persulfate,and the degradation effect of phenol under different influencing factors such as the amount of activator,the amount of persulfate,the initial p H value,the initial concentration of pollutants and inorganic anions was studied.Combined with characterization analysis and quenching experiment,the reaction mechanism of phenol degradation by activation system was discussed,and the recycling capacity of the material was investigated.The conclusions are as follows:（1）Modified biogas slag biochar ZBC-800 was obtained by high-temperature pyrolysis in a muffle furnace at 800℃and modified by dilute HCl.After acid modification,the specific surface area of ZBC-800 is increased,the degree of graphitization is improved,and the surface functional groups are more abundant,which enhances the ability of the biochar surface to transfer electrons.Moreover,the increased C=O content on the surface of the modified material was conducive to activating PS and improving the ability of degradation of organic pollutants.（2）The initial concentration of phenol solution is 50 mg/L,the initial p H value of the solution is 6.80,the dosage of activator is 0.5 g/L,the dosage of PS is 0.25 g/L（the molar ratio of PS to phenol is 2:1）,and the reaction time is 120 min.The degradation rate of phenol in ZBC-800 activated PS system reached 91.58%,realizing the efficient degradation of phenol.The degradation rate of phenol by activated PS can still reach75.23%after ZBC-800 has been recycled for 3 times.Under the optimal experimental conditions of ZBC-800 dosage of 8.94 g/L,PS dosage of 0.5 g/L,initial p H=3,the degradation rate of phenol containing coking wastewater by z BC-800 activated PS system reached 86.09%after 120 min reaction.The results show that ZBC-800activated PS system has the ability of practical application in the treatment of phenol containing coking wastewater.（3）The degradation rate of phenol in ZBC-800 activated PS system increased with the increase of ZBC-800 dosage,but the degradation rate of PS in high concentration decreased due to the mutual quenching of free radicals.ZBC-800 activated PS showed good activity when the initial p H value of the system ranged from 4.10 to 10.00.The addition of Cl^-,SO₄^2-,NH₄⁺,NO₂^-and NO₃^-had no significant effect on the final degradation effect of phenol,indicating that ZBC-800 activated PS had strong anti-interference ability and universality.（4）ZBC-800 activated PS and degraded phenol mainly through ¹O₂ and electron transfer non-free radical pathway,in which there may be two reaction paths.The first reaction path is that the sp2 graphite carbon skeleton of ZBC-800 acts as a medium of electron transfer in the activation reaction to promote the hydrolysis of PS and produce¹O₂ oxidation degradation pollutant phenol.In the second reaction path,C=O on the surface of ZBC-800 was used as the active site to activate PS to produce ¹O₂ and attack the target pollutant phenol to form intermediate para-benzoquinone to complete the degradation of phenol.