Effect of pectin on adsorption of Cu(II) by two variable-charge soils from southern China.
The influence of pectin on Cu(II) adsorption by two variable-charge soils (an Oxisol and an Ultisol) was investigated. Pectin increased the adsorption, and the extent of adsorption increased linearly with the dose of pectin, being greater in the Oxisol than that in the Ultisol because the adsorption of pectin by the Oxisol was greater. Both Langmuir and Freundlich equations fitted the adsorption isotherms of Cu(II) for both soils well. The fitting parameters of both equations indicated that pectin increased not only the adsorption capacity of the soils for Cu(II) but also the adsorption strength of Cu(II). The effect of pectin decreased with rising pH in the pH range 3.5-6.0, although the extent of electrostatic adsorption of Cu(II) by both soils was markedly greater over the pH range. Fourier-transformed infrared spectroscopy analysis and zeta potential measurement of soil colloids indicated that adsorption of pectin by the soils made the negative charge on both soils more negative, which was responsible for the increase in the electrostatic adsorption of Cu(II) induced by the addition of pectin. In conclusion, pectin-enhanced adsorption of Cu(II) especially at low pH would be beneficial to the soils as it would decrease the activity and mobility of Cu(II) in acidic variable-charge soils.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.|College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
Ru-hai
RH
Wang
College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.|Nanjing Institute of Supervision & Testing on Product Quality, Nanjing, 210028, People's Republic of China.
Xiao-fang
XF
Zhu
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
Wei
W
Qian
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.|College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
Yuan-chun
YC
Yu
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.
Ren-kou
RK
Xu
D000327:Adsorption; D001711:Biotransformation; D002681:China; D003102:Colloids; D003300:Copper / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010368:Pectins / Q000494:pharmacology*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000378:metabolism*
D003102:Colloids; D012987:Soil; D012989:Soil Pollutants; D003300:Copper; D010368:Pectins
Adsorption; Cu(II); Pectin; Surface charge; Surface complexes; Variable-charge soil