Study On The Treatment Of Antibiotics In Mariculture Wastewater Using Modified Carbon Fiber

In this paper,the effect of modified carbon fiber?CF?on the adsorption of four kinds of antibiotics in mariculture wastewater?tetracycline hydrochloride,chlortetracycline hydrochloride,chlortetracycline hydrochloride and sulfonamide?was studied.The carbon fiber was modified with sulfuric acid.The carbon fiber and carbon fiber modified by sulfuric acid modification for 45 min and 60 min were characterized by SEM,BET,FTIR,pore size analysis and pore volume analysis.FTIR results showed that there was no significant change in surface functional groups after modification,indicating that the carbon skeleton of the carbon fiber was not destroyed.SEM shows that the acid modification corrodes the surface pores,and the CF surface has pits and collapses.The BET results showed that the specific surface area of CF after acid modification was significantly increased from the original 848 m²/g to 1122m²/g and 1227 m²/g.The pore size analysis showed that the pore size of the modified carbon fiber was still mainly based on micropores,and pore volume analysis showed that the pore volume of the carbon fiber surface after acid modification had a certain increase.The carbon fiber was modified by iron.The modified carbon fiber was subjected to SEM,BET,FTIR,pore size analysis,pore volume analysis,XRD,EDS and other characteristics.FTIR results showed that there was no significant change in surface functional groups after modification,indicating that the carbon skeleton of the carbon fiber was not destroyed.SEM shows that the iron is evenly distributed on the surface of carbon fiber,and the BET results show that the specific surface area of the carbon fiber after iron modification is reduced from the original 848 m²/g to 779 m²/g.The pore size analysis showed that the pore size of the modified carbon fiber was still mainly based on micropores,and pore volume analysis shows that the pore volume on the surface of the carbon fibers after acid modification is reduced.XRD,EDS analysis showed that iron was successfully loaded on the surface of carbon fiber in the form of Fe₃O₄.The adsorption of tetracycline hydrochloride,chlortetracycline hydrochloride,chlortetracycline hydrochloride and sulfonamide on sulfuric acid modified carbon fiber was studied.The single factors?modification time,adsorption time,pH value,antibiotic concentration,ionic strength,carbon fiber dosage?affecting the removal of tetracycline hydrochloride,chlortetracycline hydrochloride,and chlortetracycline hydrochloride were studied.A 16-factor orthogonal experiment with five-factor and four-level was designed to determine the optimal conditions for the removal of antibiotics.The adsorption mechanisms of tetracycline hydrochloride,chlortetracycline hydrochloride,chlortetracycline hydrochloride and sulfonamide were studied.Four kinetic models were used to fit the adsorption kinetics.The experimental results show that the pseudo second-order kinetics can best reflect the adsorption kinetics of the four antibiotics.Adsorption isotherm were fitted using two adsorption isotherm models.The experimental results show that Langmuir model can best reflect the adsorption process of four antibiotics,among which tetracycline hydrochloride,chlortetracycline hydrochloride,chlortetracycline hydrochloride,sulfonamide maximum adsorption capacity on carbon fiber was 68 mg/g,62 mg/g,87mg/g,and 209 mg/g,respectively.In addition,the paper studied the thermodynamic characteristics of sulfanilamide adsorption.The thermodynamic result showed that the adsorption reaction of sulfanilamide was spontaneous and exothermic physical reaction.The adsorption effect of iron-modified carbon fiber on tetracycline hydrochloride was studied.The reaction mechanism?pH value,kinetics,adsorption isotherm,and adsorption thermodynamics?was studied.The results showed that,compare with carbon fiber,the iron modified carbon fiber has adsorption ability for tetracycline.Four kinetic models were used to fit the adsorption kinetics.The experimental results show that the pseudosecond-order kinetics can best reflect the kinetics of the adsorption of tetracycline hydrochloride on iron-modified carbon fibers.Adsorption kinetics were fitted using four adsorption isotherm models.The experimental results show that the Langmuir model can best reflect the adsorption process of tetracycline hydrochloride on iron-modified carbon fibers with a maximum adsorption capacity of58 mg/g.The thermodynamic characteristics of sulfanilamide adsorption showed that the sulfanilamide adsorption reaction is a spontaneous and endothermic physical reaction.The adsorption thermodynamic characteristics of the four antibiotics indicate that the adsorption reaction of tetracycline antibiotics is a spontaneous,endothermic physical reaction;the adsorption reaction of sulfonamides is spontaneous,exothermic physical adsorption.The adsorption thermodynamic characteristics of the four antibiotics indicate that the adsorption reaction of tetracycline antibiotics is a spontaneous,endothermic physical reaction;the adsorption reaction of sulfonamides is spontaneous,exothermic physical adsorption.The optimum conditions for each adsorption reaction can be obtained by orthogonal experiment.The optimal conditions for the adsorption of tetracycline by iron-ion-modified carbon fiber are:0.04 g modified CF dosage,10 mg/L tetracycline initial concentration,2 h reaction time,pH value of 7.Under this condition,the removal rate can reach 98%.The optimal conditions for the adsorption of four tetracycline antibiotics by sulfuric acid modified carbon fiber are:TH:45 min modification time,0.03 gCF modification time,15 mg/L oxytetracycline initial concentration,3 h reaction time,pH value 6;CTC:60 min modification time,0.04gCF modification time,20 mg/L chlortetracycline initial concentration,4 h reaction time,pH value 6;TC:45 min modification time,0.03 g CF modification Time,initial concentration of 20 mg/L tetracycline,3 h reaction time,pH value 6.At this time,the removal rate of the three antibiotics can reach more than 90%;sulfonamide:45 min modification time,0.03 g CF dosage,initial concentration of 15 mg/L sulfonamide,0.5 h reaction time,pH value 6,under this condition,the removal rate can reach 99%.The regeneration of sulphuric acid-modified carbon fiber after saturated adsorption of tetracycline hydrochloride,chlortetracycline hydrochloride and chlortetracycline hydrochloride was studied.The regeneration method was thermal regeneration.The experimental results showed that after four regenerations.The regeneration rates of tetracycline,chlortetracycline hydrochloride and chlortetracycline hydrochloride on carbon fiber are 47%,68%,24%,respectively.