Activation Of Peroxodisulfate By Peanut Shell-derived Biochar Composite For The Removal Of Tetracycline In Wastewater

In recent years,with the advancement of technology and the accelerated development of industrialization,industries such as the medical industry and animal husbandry have been developing rapidly,and the amount of sewage that has come has also continued to increase.These wastewaters contain high levels of antibiotic contaminants.Inaddition,these antibiotics are not easy to be degraded under normal environmental conditions,they are easy to accumulate in the environment,and are transmitted in organisms through the food chain.Therefore,corresponding measures must be taken to deal with antibiotic contaminants in water bodies.In this study,peanut shell biochar was used as a raw material to prepare biochar（BC）,and modified with ferric nitrate and zinc chloride to improve the performance of peanut shell biochar.The research selects tetracycline as the target pollutant to determine the catalytic performance of the composite material.The main work is as follows:（1）The peanut shell biomass is made into biochar by pyrolysis,and the co-precipitation method is adopted for modification.The peanut shell biomass and ferric nitrate are mixed to prepare BC-Fe composite materials with different mass ratios.The mass ratio is:10%,20%,30%,40%.The pseudo-first-order kinetic model is used to analyze the degradation efficiency of tetracycline.When the dosage of ferric nitrate is1g,the mass ratio of BC-Fe is 20%,and the removal rate of pollutants is the highest.On the basis of the optimal loading ratio,1g of zinc chloride was added to prepare the BC-Fe-Zn ternary composite material.The degradation rate of tetracycline（TC）of the material was 88.60%within 120 minutes,and the modified composite material The catalytic performance is significantly higher than the BC and BC-Fe alone.（2）According to the scanning electron microscope（SEM）,specific surface area and pore size distribution analyzer（BET）,X-ray diffractometer（XRD）characterization results,the iron element was granular on the BC surface,and successfully attached to the BC surface together with the zinc element.When the p H of the solution is less than7,the degradation rate of TC within 120 minutes is about 90%.The results of the zeta potential show that the potential of BC-Fe-1-Zn is negative and the value is the smallest.TC is positively charged when the p H is less than 4,so the Zeta potential data verification shows that the removal effect is the best when p H=3,the optimal p H value.（3）In the ion experiment,the reaction conditions of the possible anions:NO₃^-,Cl^-,SO₄^2-and undoped anions were used for comparison experiments.The results showed that these ions had little effect on the degradation of TC.Then put Et OH,TBA,BQ and Na N₃ to carry out free radical quenching experiments.The results found that these substances all have inhibitory effects on the degradation of TC in the BC-Fe-1-Zn/PS/TC degradation system,but the inhibitory effects of Et OH and TBA are the most obvious.Explain that the main types of active substances are SO₄^·-and·OH.The electrochemical analysis of the degradation system shows that the BC-Fe-1-Zn composite material has good electron transfer ability,the electron transfer path exists in the system,and it is beneficial to the degradation of TC by BC-Fe-1-Zn.（4）Through fourier transform infrared spectroscopy（FTIR）and X-ray electron spectroscopy（XPS）characterization analysis of BC-Fe-1-Zn material,the results show that the surface functional groups-OH,-CO and-CH of BC-Fe-1-Zn may participate in the PS activation process and may adsorb TC and its intermediate products;C-C,C-O,C=O bonds can electrostatically adsorb TC and its intermediate products produced in the degradation process;iron and zinc may participate in the activation process of PS in an indirect or direct manner,and between these two elements will not inhibit each other and reduce the catalytic degradation effect.