Pedosphere 30(6): 844--852, 2020
ISSN 1002-0160/CN 32-1315/P
©2020 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Specific ion effect of H+ on variably charged soil colloid aggregation
Yekun ZHANG, Rui TIAN, Jia TANG, Hang LI
Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, College of Resources and Environment, Southwest University, Chongqing 400715(China)
ABSTRACT
      Specific ion effects (Hofmeister effects) have recently attracted the attention of soil scientists, and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil. However, this explanation cannot be applied to H+. The aim of this work was to characterize the specific ion effect of H+ on variably charged soil (yellow soil) colloid aggregation. The total average aggregation (TAA) rate, critical coagulation concentration (CCC), activation energy, and zeta potential were used to characterize and compare the specific ion effects of H+, K+, and Na+. Results showed that strong specific ion effects of H+, K+, and Na+ existed in variably charged soil colloid aggregation. The TAA rate, CCC, and activation energy were sensitive to H+, and the addition of a small amount of H+ changed the TAA rate, CCC, and activation energy markedly. The zeta potential results indicated that the specific ion effects of H+, K+, and Na+ on soil colloid aggregation were caused by the specific ion effects of H+, K+, and Na+ on the soil electric field strength. In addition, the origin of the specific ion effect for H+ was its chemical adsorption onto surfaces, while those for alkali cations were non-classic polarization. This study indicated that H+, which occurs naturally in variably charged soils, will dominate variably charged soil colloid aggregation.
Key Words:  activation energy,chemical adsorption,critical coagulation concentration,dynamic light scattering,Hofmeister effect,total average aggregation rate,zeta potential
Citation: Zhang Y K, Tian R, Tang J, Li H. 2020. Specific ion effect of H+ on variably charged soil colloid aggregation. Pedosphere. 30(6):844-852.
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