Batch sorption experiments were conducted to evaluate the sorption behavior of tetracycline(TC,H_(3)L)on sediments and soils in the presence and absence of cadmium(Cd),as affected by pH and properties of sediments and...Batch sorption experiments were conducted to evaluate the sorption behavior of tetracycline(TC,H_(3)L)on sediments and soils in the presence and absence of cadmium(Cd),as affected by pH and properties of sediments and soils.The results indicated stronger nonlinearity and higher capacity of TC sorption on sediments than on soils.Sorption of TC also strongly depended on environmental factors and sediment/soil properties.Lower pH facilitated TC sorption through a cation exchange mechanism,which also took place at pH values above 5.5,where TC existed as a zwitterion(H_(2)L^(0))or anions(HL^(-)and L^(2-)).When pH was above 7,however,ligand-promoted dissolution of TC might occur due to TC weakening the Al-O bond of aluminum oxide and the Fe-O bond of iron oxide.Natural organic matter(NOM)plays a more important role in TC sorption than cation exchange capacity(CEC)and clay contents.The presence of Cd(II)increased TC sorption on both sediments and soils,which resulted from the decrease of equilibrium solution pH caused by Cd^(2+)exchange with H^(+)ions of sediment/soil surfaces.The increase of TC sorption was also related to the formation of TC-Cd complexes,where Cd^(2+)acted as a bridge between the sediment/soil and TC.展开更多
基金The study was supported by the Ministry of Science and Technology(No.2007CB407302)the National Natural Science Foundation of China(Grant No.40971058)Beijing Normal University(No.2009SD-19).
文摘Batch sorption experiments were conducted to evaluate the sorption behavior of tetracycline(TC,H_(3)L)on sediments and soils in the presence and absence of cadmium(Cd),as affected by pH and properties of sediments and soils.The results indicated stronger nonlinearity and higher capacity of TC sorption on sediments than on soils.Sorption of TC also strongly depended on environmental factors and sediment/soil properties.Lower pH facilitated TC sorption through a cation exchange mechanism,which also took place at pH values above 5.5,where TC existed as a zwitterion(H_(2)L^(0))or anions(HL^(-)and L^(2-)).When pH was above 7,however,ligand-promoted dissolution of TC might occur due to TC weakening the Al-O bond of aluminum oxide and the Fe-O bond of iron oxide.Natural organic matter(NOM)plays a more important role in TC sorption than cation exchange capacity(CEC)and clay contents.The presence of Cd(II)increased TC sorption on both sediments and soils,which resulted from the decrease of equilibrium solution pH caused by Cd^(2+)exchange with H^(+)ions of sediment/soil surfaces.The increase of TC sorption was also related to the formation of TC-Cd complexes,where Cd^(2+)acted as a bridge between the sediment/soil and TC.
