Preparation Of Biochar By Pyrolysis Of Penicillin Residue And Its Adsorption Properties

As a big country in the production,use,and export of antibiotics,the large production of antibiotics must be accompanied by dramatic increases in the production of bacterial residue.Penicillin is an antibiotic widely used inβ-lactam antibiotics.Penicillin residue is a solid organic waste formed by microbial fermentation in the process of preparing penicillin.Due to the high moisture content,unstable properties,and antibiotic residues of penicillin residue,direct discharge without treatment will cause a serious impact on the environment.Penicillin residue contains protein,fiber,lipid,inorganic salt,and other biomass resources,which lays the foundation for its high-value application.At present,the treatment technologies for penicillin residue include incineration,anaerobic digestion,compost,pyrolysis,etc.By contrast,pyrolysis technology has the advantages of low emission of dioxins,NOx,and SOx,low environmental impact,and high-quality fuel production.In this paper,pyrolysis technology is used to study the treatment of penicillin residue.Through industrial analysis,organic element analysis,and Infrared spectroscopy（FTIR）analysis,it was confirmed that the bacteria residue contained protein,lipids,and other organic matter,which could realize resource utilization.Thermal analysis showed that its calorific value was much higher than that of lignite and anthracite,and its heavy metal content was much lower than the pollution emission limit.Moreover,the degradation behavior of antibiotics was analyzed,which confirmed the feasibility of pyrolysis treatment of penicillin bacteria residue.The thermogravimetric method was used to analyze the pyrolysis behavior of penicillin residue.Heat transfer restriction caused the temperature corresponding to the maximum weight loss rate would shift to a high temperature with the increase in the heating rate.Thermodynamics showed that the pyrolysis reaction was a non-spontaneous and irreversible process,and the activation energy of the reaction was about 200 k J·mol^-1 by Flynn-Wall-Ozawa（FWO）and Kissinger-Akahira-Sunose（KAS）.A mechanism function model was established:G（α）=[1-（1-α）^1/3]^6.1025,which provided theoretical basis for the pyrolytic treatment of penicillin residue.The effects of pyrolysis final temperature,heating rate,and residence time on the three-phase yield of penicillin residue were investigated.The solid products after pyrolysis were analyzed.The chemical changes in the reaction were mainly dehydration,the formation and elimination of the carbonyl group,the removal of the aliphatic side chain,and the formation of aromatic carbon units.The heating rate and residence time mainly affect the aromatization process.At the same time,according to the analysis of biochar characteristics,the best conditions for preparing biochar are a final temperature of 400℃,a heating rate of20℃·min^-1,and a residence time of 30 min.Finally,the optimal biochar was selected to explore the contact time,temperature,dosage of biochar,and initial concentration of methylene blue.It was found that different experimental conditions had certain effects on the adsorption process,which was mainly related to the active adsorption sites.According to the adsorption data,the adsorption kinetics and adsorption isotherm model were fitted.The adsorption reaction was in line with the quasi-second-order kinetic model（R²>0.99）,and the adsorption isotherm was in line with the Freundlich model（R²>0.99）,which confirmed that the preparation of biochar from penicillin residue had certain application prospect in the treatment of wastewater.