Effect Of Soil Component On The Adsorption Of Antibiotic And Heavy Metal On Soil And Biochar

The combined pollutant of heavy metal and antibiotic in soil usually caused the stronger eco-toxicity and higher abundance of antibiotic resistant genes than a single pollutant,which thus poses a potential and huge threat to human health.Adsorption is one of the most effective methods in controlling mobility and bioavailability of soil contaminants.Biochar has become a promising soil amendment due to its huge specific surface area,abundant pore strcture and O-containing functional group.In this dissertation,a natural black soil was treated to obtain three individual soils which had different properties,in order to investigate the role and contribution of different soil components(organic matter,metal oxide,and clay)to tetracycline,Cu2+,and Cd2+adsorption;Biochars produced from wheat straw at 400 °C and 700 °C were treated with three typical soil minerals to examine the effects of soil minerals on biochar properties and adsorption capacity for sulfamethoxazole through a series of characterizations including Boehm titration and mediated electrochemical technique.These results are helpful in evaluating the application of biochar in alleviating and controlling the soil contaminant by studying the interaction between biochar and soil/soil component.The main original conclusions of this work are presented as follow:(1)The contribution of different soil components toward adsorption of antibiotics?i and heavy metals and the effect of heavy metals on adsorption of antibiotics on the separated components from natural soil were studied.The adsorption amount of ROM,ROX,and HA for TC was greater than that of BS by 1.2 times,2.3 times,and 3.3 times at an initial TC concentration of 25 mg L"1.Soil organic matter made the greatest contribution toward the adsorption of tetracycline(TC),followed by clay and metal oxide,whereas,metal oxide was the most key component influencing the adsorption of Cu2+ and Cd2+.The presence of Cu2+ enhanced the TC adsorption on BS,ROM and ROX,but had a suppression effect on HA because of the competition of Cu2+.The presence of Cd2+ did not exert obvious effect on TC adsorption on BS due to weak binding affinity with TC,but exhibited a suppression efTect on TC adsorption on ROM,ROX and HA.(2)The effect of soil minerals on biochar properties and adsorption capacity for sulfamethoxazole(SMX)was studied.Mineral treatment enlarged the surface area and pore size of biochar,and the electron donating capacity(EDC)of the mineral-treated biochars also increased due to the increased phenolic group in BC400 and the enhanced conjugated 7t-electron system in BC700,respectively.The adsorption of SMX on BC700 was increased after mineral treatment due to the facilitating effect of electron donor-acceptor interaction.In contrast,mineral treatment decreased SMX adsorption on BC400,which could be attributed to the potential association of organic matter with minerals via coprecipitation and adsorption,in addition to the weak adsorption capacities of soil minerals for SMX.