The Characteristics Of Biochars Derived From Rice Straw And Swine Manure And Their Adsorption Properties For Tetracycline

Antibiotics are widely used in the control of infectious diseases in humans and animals,as well as animal growth promoters for livestock and poultry farming.Tetracyclines（TCs）are one of the most frequently used antibiotics.According to statistics,the consumption of TCs was ranked second in the world,but first in China.Approximate70-90%TCs can not be metabolized by organisms,and then released in the environment as unchanged form.TC may be carcinogenic on chronic exposure,hence,the removal of TC should be paid significant attention.Among many treatment technologies,removal of pollutants by biochar have been studied extensively.According to previous studies,biochars have good sorption ability of heavy metals（Cu,Zn,Hg,etc.）and organic pollutants（PAHs,PCBs,HOCs,etc.）but the research about biochar adsorbed emerging organic pollutants such as antibiotics is few.Therefore,this study was conducted to explore the sorption ability of TC onto biochars produced from rice straw and swine manure.In this study,the rice straw as well as swine manure were chose to produce biochars and also the modification was applied to improve the sorption ability of biochar.The raw and H₃PO₄ modified biochars derived from rice straw were named as RC and RCA,respectively.Also,the raw and H₃PO₄ modified biochar produced from swine manure were recorded as SC and SCA,respectively.These biochars were characterized by SEM-EDS,FTIR,BET,and EA.Through this study,it is expected to reveal that the difference between raw and H₃PO₄ modified biochar derived from rice straw and swine manure,2)to understand the adsorption capacities and mechanism of raw and H₃PO₄modified biochar derived from rice straw and swine manure for TC in water.Moreover,the improved sorption capacities of yellow soil（YES）,paddy soil（PAS）and purple soil（PUS）by 2%biochar amendment was also tested in this study.the adsorption capacities and mechanism of soils contained respectively 2%RCA and SCA.The main results are demonstrated as follows:（1）Biochar derived from rice straw had higher surface area than biochar derived swine manure,no matter H₃PO₄ treatment was applied.The FTIR results showed that the functional groups of four kinds of biochar were similar.H₃PO₄ modification enhanced the surface area and the content of C,N and S of raw biochar,and reduced the content of O of raw biochar.However,the Ca,Na and F contents were emilinated after H₃PO₄modification..（2）H₃PO₄ modification enhanced the adsorption capacity of TC on biochar,especially SCA（about 25%enhancement）.RCA had stronger adsorption capacity and higher adsorption ability than SCA.The H-bonding andπ-πEDA interaction might be the primary sorption mechanisms for the sorption of TC on RCA and SCA.Relative to other biochars,RCA and SCA demonstrated high sorption abilities and capacities of TC,and might be good sorption materials for TC removal from water,although the sorption of TC on SCA was lower than RCA.（3）The adsorption equilibrium time and rate of the same soil amended with 2%SCA and RCA were close.By comparison,biochar addition significantly improved the sorption capacities of three soils,but the improvement was different among various soils.Relative to YES and PUS,the equilibrium time of PAS for TC sorption was shorter,and the adsorption capacities of PAS and PUS for TC were higher than that of YES.After biochar addition,the adsorption capacities of PAS and PUS amended 2%biochar for TC were higher than YES with 2%biochar.Furthermore,it is found that the pH could affect the sorption capacitie of TC to soils amended with biochars.The general trends of TC adsorbed on soils with 2%biochars wereincreasing-decreasing for YES,and decreasing for PUS and PAS from pH 2.0 to 11.0.It is noteworthy that the adsorption capacities of different soils contained 2%SCA and RCA respectively were improved for TC at all pH values（P<0.05）.In conclusion,biochars derived from rice straw and swine manure showed good adsorption abilities and capacities for TC in water,especially H₃PO₄ modified biochars.Moreover,2%biochar addition could enhance the sorption capacities of TC on yellow soil,purple soil and paddy soil.From this stuy,it can be known that rice straw and swine manure could good materials for biochar production,and the producd biochars,especially H₃PO₄ modified biochars,have great potentials for TC removal from water and soil.