title: Adsorption of Cd(II) by two variable-charge soils in the presence of pectin.
abstract: Batch experiments were conducted to investigate cadmium(II) (Cd(II)) adsorption by two variable-charge soils (an Oxisol and an Ultisol) as influenced by the presence of pectin. When pectin dosage was less than 30 g kg(-1), the increase in Cd(II) adsorption with the increasing dose of pectin was greater than that when the pectin dosage was >30 g kg(-1). Although both Langmuir and Freundlich equations fitted the adsorption isotherms of Cd(II) and electrostatic adsorption data of Cd(II) by the two soils well, the Langmuir equation showed a better fit. The increase in the maximum total adsorption of Cd(II) induced by pectin was almost equal in both the soils, whereas the increase in the maximum electrostatic adsorption of Cd(II) was greater in the Oxisol than in the Ultisol because the former contained greater amounts of free Fe/Al oxides than the latter, which, in turn, led to a greater increase in the negative charge on the Oxisol. Therefore, the presence of pectin induced the increase in Cd(II) adsorption by the variable-charge soils mainly through the electrostatic mechanism. Pectin increased the adsorption of Cd(II) by the variable-charge soils and thus decreased the activity and mobility of Cd(II) in these soils.
authors.affiliation: Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.|State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
authors.forename: Ru-Hai
authors.initials: RH
authors.lastname: Wang
authors.affiliation: Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.|Nanjing Institute of Product Quality Inspection, Nanjing, 210028, People's Republic of China.
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Zhu
authors.affiliation: Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.|State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Qian
authors.affiliation: Nanjing Institute of Product Quality Inspection, Nanjing, 210028, People's Republic of China.
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China. rkxu@issas.ac.cn.
authors.forename: Ren-Kou
authors.initials: RK
authors.lastname: Xu
authors.affiliation: Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China. ycyu@njfu.edu.cn.
authors.forename: Yuan-Chun
authors.initials: YC
authors.lastname: Yu
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010368:Pectins / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D055672:Static Electricity
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D010368:Pectins
keywords: Adsorption; Cd(II); Pectin; Surface charge; Variable-charge soil