Research On The Preparation Of Bagasse Based Biochar And Adsorption Of Tetracycline From Aqueous Solution

The potential risks of environment and human health were caused by antibiotic pollution in water environment that has aroused wide public concern.In recent years,agricultural and forestry wastes as raw materials were used to prepare biochar which has the characteristics of high degree of aromaticity,large specific surface area and abundant pore structure,therefore,biochar was used as an inexpensive and environmentally friendly adsorbent for adsorption of antibiotics.The physical and chemical properties of BC are directly affected by raw materials and conditions of preparation that also determine the adsorption performance of BC for antibiotics.In this paper,bagasse which is from the main crop of Guangxi:sugarcane was used as raw material for preparation of BC,and the adsorption performance of BC for antibiotics from aqueous solution was studied.In this study,bagasse as raw material,bagasse based biochars(BBC)were prepared by respectively using ZnCl2 and H3PO4 as activator.The effects of activator concentration,carbonization temperature and carbonization residence time on adsorption performance of BBC were studied.As for the antibiotic of maximun consumption:tetracycline BBC was modified by acetic acid and ethylenediamine respectively,then the modified bagasse based biochars(M-BBC)were used to adsorb tetracycline from aqueous solution.The effects of adsorption time,initial concentration of tetracycline and adsorption temperature on the adsorption performance of M-BBC for tetracycline were studied.The samples of BBC were characterized by specific surface area and pore analyzer,XRD,elemental analyzer,Raman spectrometer,FT-IR and SEM.The adsorption process and mechanism of BBC and M-BBC for tetracycline were studied by adsorption kinetics,adsorption isotherm and adsorption thermodynamic.Here are the results of this study.(1)Bagasse as raw material,bagasse based biochar with ZnCl2 activation(Z-BBC)and bagasse based biochar with H3PO4 activation(P-BBC)were prepared by respectively using ZnCl2 and H3PO4 as activator.Z-BBC has lower preparation cost and better adsorption performance than P-BBC.The preparation conditions of Z-BBC:concentration of ZnCl2 is 15 wt%,carbonization temperature is 350? and carbonization residence time is 60 min.The maximum iodine adsorption capacity of Z-BBC is 1083.622 mg/g,the specific surface area is 1247.3 m2/g,the total pore volume is 0.6397 cm3/g and the average pore diameter is 2.285 nm.The Z-BBC is rich in microporous structure and has a lot of oxygen-containing functional groups on surface of Z-BBC.(2)Bagasse based biochar with acetic acid modification(AM-BBC)and bagasse based biochar with ethylenediamine modification(EM-BBC)were modified by acetic acid of 15 vt%and ethylenediamine of 5 vt%respectively.The specific surface area of AM-BBC and EM-BBC are 1601.598,803.787 m2/g respectively,the total pore volume are 0.811,0.392 cm3/g respectively and the average pore diameter are 2.251,2.166 nm respectively.The adsorption capacity of AM-BBC,EM-BBC and Z-BBC for tetracycline were 453.339,267.210 and 410.275 mg/g respectively that indicate modification of acetic acid observably increased the adsorption capacity of Z-BBC for tetracycline,modification of ethylenediamine decreased the adsorption capacity of Z-BBC for tetracycline.(3)The maximum adsorption capacity of Z-BBC and AM-BBC for tetracycline from aqueous solution were 501.270,599.297 mg/g respectively.The adsorption kinetics of Z-BBC and AM-BBC conformed to the pseudo-second kinetic model.The adsorption isotherm of Z-BBC and AM-BBC conformed to Redlich-Peterson model(R-P model)and Tempkin model.Thermodynamic analysis showed that adsorption of Z-BBC and AM-BBC for tetracycline is endothermic process,AM-BBC has stronger adsorption ability for tetracycline than Z-BBC.FT-IR analysis showed that tetracycline is adsorbed by the reaction between tetracycline molecules and functional groups on surface of biochar.