אסיף מאגר המחקר החקלאי

Organo-modification effects on soil particles-inorganic cations interactions as revealed by wien effect measurements soil chemistry

Year:

2013

Source of publication :

Authors :

Volume :

77

Co-Authors:

Wang, Y., Key Laboratory of Soil Environment and Pollution Remediation, Inst. of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Li, C., Key Laboratory of Soil Environment and Pollution Remediation, Inst. of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Wang, L., Key Laboratory of Soil Environment and Pollution Remediation, Inst. of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Zhou, D., Key Laboratory of Soil Environment and Pollution Remediation, Inst. of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Si, Y., College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China
Friedman, S.P., Volcani Center, Inst. of Soil, Water and Environ.Sci., Agricultural Research Organization, Bet Dagan 50250, Israel

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Abstract:

The behavior of soil and clay particles modified with organic cations and anions (surfactants) is of interest mostly in the context of the enhanced retentive properties of the modified particles to organic pollutants. However, the adsorption of organic ions on the surfaces of the soil particles has other consequences, and the present article addresses one of them, that is, the effects of preadsorbed organic ions on the interactions between soil particles and inorganic cations. To characterize this effect we applied the previously established method of measuring the Wien effect, that is, the increase in electrical conductivity of dilute suspensions with increasing applied electrical field. A paddy soil and a latosol were modified with two surfactants-cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl-sulfonate (SDS)-and were used to study the effects of organo-modifiers on the interactions between counter ions and soil particles by means of Wien effect measurements. The variations with field strength (E) of the electrical conductivities (EC) of the suspensions of the paddy soil were strongly related to the concentration of preadsorbed cetyl-trimethylammonium (CTA), whereas the EC vs. E curves of the organo-modified and natural latosol suspensions were almost flat. The mean free binding energies, ΔGbi, of K+ and Cd2+ to the paddy soil decreased with increasing concentration of CTA and the ΔGbi of Cd2+ to the natural paddy soil was larger than that of K+, but the ΔGbi of Cd2+ to organo-modified paddy soils were lower than those of K+. The stripping intensities (Is) of K+ and Cd2+ adsorbed on surfaces of natural paddy soil were 0.155 and 0.165 μS kV-1, respectively; they rapidly decreased with increasing CTA concentration, and then decreased slowly toward zero. In the organomodified paddy soil Is values of K+ were always larger than those of Cd2+. The Is values of inorganic cations adsorbed on surfaces of latosols were close to zero for both the natural and the SDS-modified soil particles. Copyright © 2013 by the Soil Science Society of America, Inc.

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