Preparation Of Penicillin Residue Biochar And Its Adsorption Performance For Tetracycline In Water

The antibiotics,as new pollutants,are difficult to effectively remove by traditional biological treatment due to their complex structure and biological toxicity.The continuous discharge into water may pose a series of environmental risks.These pollutants were usually removed by adsorption,membrane separation,and advanced oxidation techniques.However,problems such as high cost,incomplete removal,and secondary pollution exist with these technologies.In this study,a new biochar was prepared by pyrolyzing penicillin residue,and its adsorption performance on the typical antibiotic,tetracycline,was investigated.Other new pollutants were also explored to test and verify its broad spectrum.Its application in actual antibiotic wastewater was discussed as well.The results of the study were as follows:1)A penicillin residue biochar（IKBCH）with high aromatization and a rich pore structure was prepared by K₂CO₃ impregnation,oxygen-limited pyrolysis at 600℃,and hydrochloric acid pickling.The specific surface area of IKBCH reached 991.395 m²·g^-1 with an average pore size of 1.758 nm,which belonged to microporous biochar.The iodine adsorption value and methylene blue adsorption value of IKBCH were 804.64 mg·g^-1 and349.88 mg·g^-1,respectively.2)The adsorption characteristics of IKBCH on tetracycline were investigated.When the initial tetracycline concentration was 200 mg·L^-1,the tetracycline removal rate was greater than 99.91%with IKBCH dosing greater than 1 g·L^-1.The adsorption capacity of IKBCH on tetracycline reached its maximum at an initial pH=4,which was 306.01 mg·g^-1.The coexisting cations Na⁺and K⁺had little effect on the adsorption,and Ca²⁺and Mg²⁺would strongly compete for adsorption.The adsorption process of IKBCH on tetracycline was in accordance with the pseudo-second order kinetic model and Langmuir isotherm model as monolayer adsorption on a homogeneous surface.The adsorption mechanisms were pore filling,π-πinteractions,hydrogen bonding and electrostatic adsorption.The IKBCH was regenerated by the hot alkali regeneration method,and the adsorption capacity of 74.20%was maintained at the third cycle.3)The extensive experiments showed that the adsorption capacities of IKBCH for the six new pollutants,ciprofloxacin,ranitidine,sulfamethoxazole,bisphenol A,atrazine,and chlorpyrifos were 216.32 mg·g^-1,142.76 mg·g^-1,181.51 mg·g^-1,319.53 mg·g^-1,98.51 mg·g^-1,and 93.64 mg·g^-1,respectively.When the respective pollutant concentration was 5 mg·L^-1,the removal rate was above 99.19%.The COD removal rates reached 94.30%and 94.95%for the treatment of oxytetracycline pharmaceutical wastewater and cephalosporin pharmaceutical wastewater by IKBCH adsorption,and both oxytetracycline and cephalosporin antibiotics were not detected.