Study On The Adsorption Of Tetracycline In Aqueous Solution By Modified Biochar

Tetracycline,as a feed additive,is widely used in animal husbandry and aquaculture,because of its non-degradable and high-residue properties,it will cause serious environmental pollution,which will change the original balance mechanism in the ecological environment,and even lead to the variation of some microbial physiological functions,producing a large number of resistance genes and cause drug resistance.Common removal methods for residual tetracycline from environment include photodegradation,biodegradation,chemical oxidation,electrochemical method and adsorption method.Because the adsorption method has the advantages of simple operation and convenient,it has been widely concerned by researchers at home and abroad.However,common adsorbents,such as activated carbon or adsorbed resin,have high cost,and the search for a low price and a wide range of sources of adsorbents has become the focus of research.Therefore,this study will use agricultural waste Auricularia auricula dregs as raw materials to prepare biochar and modify it to further explore the adsorption performance of tetracycline.(1)In this paper,the original biochar(BC-300,BC-500,and BC-700)was prepared using tetracycline as the representative contaminant and prepared biochars with different temperatures derived from Auricularia auricula dregs.Alkali modified biochar(BC-2M,BC-4M,and BC-8M)was prepared using different concentrations of Na OH solution.Finally,magnetization biochar(MBC-1 and MBC-2)were performed on this basis to facilitate subsequent solid-liquid separation steps.(2)In this study,the physicochemical properties of biochars were analyzed,mainly including SEM analysis,surface area and aperture analysis,surface functional group titration analysis,X-ray diffraction analysis and FTIR analysis.The results show that the high temperature will make the biochar carbonization more complete,the specific surface area after modification is increased,the pore is more developed,and it is more favorable for adsorption.(3)The single factors explored in the adsorption experiments were contact time,dosages of adsorbents,solution initial p H,ionic concentration in solution,temperature and desorption regeneration.The results showed that the optimum dosage of raw biochar was 3.2 g/L,the optimum dosages of modified biochar and MBC were 1.4 g/L,the adsorption equilibrium time was 4-6 h,and the optimum adsorption under neutral conditions.(4)Using pseudo-first-order kinetics and pseudo-second-order kinetics models,it is found that the original biochar was more consistent with pseudo-first-order kinetics,and the modified biochar and MBC-1 were more consistent with pseudo-second-order kinetics;Langmuir,Freundlich,Temkin and Dubinin-Raduskevich isotherm model was fitted and the maximum adsorption capacity of the original biochar BC-300,BC-500 and BC-700 were calculated as 7.22 mg/g,9.90 mg/g and 11.90 mg/g,the maximum adsorption capacity of alkali modified biochar BC-2M,BC-4M and BC-8M were 23.41 mg/g,25.11 mg/g and 26.65 mg/g,respectively,and the maximum adsorption capacity of MBC-1 and MBC-2 were 27.47 mg/g and 33.56 mg/g,respectively.(5)The main mechanism of adsorption of tetracycline by biochar is ?-? EDA interaction,which also includes pore filling,hydrogen bonding and inter-electron interaction.In this study,biochar was prepared by using biomass Auricularia auricula dregs and modified,the adsorption effect was good,the adsorption rate was fast,the adsorbent material was cheap and easy to obtain,and the preparation process was simple and environmentally friendly.