open access

https://hdl.handle.net/2115/70737

Sulfate adsorption and surface precipitation on a volcanic ash soil (allophanic andisol)

英語

Multilayer adsorption

2006-08-15

Elsevier

Journal of Colloid and Interface Science

300(2)

504-510

Sulfate strongly adsorbs on metal oxides and soils with variable charges. However, its surface precipitation has not been clearly evaluated and its adsorption mechanism has been in dispute. In the present study, an allophanic andisol, a typical volcanic ash soil having both negative and positive variable charges, was used to identify the adsorption mechanism of sulfate. Sulfate adsorption isotherms were obtained by a batch method at pH values of 4, 5, 6, and 7 in a wide range of concentrations in an Na–H–SO4–OH system. Theoretical isotherms were applied to the measured values for the evaluation. The surface precipitation was detected by the measured adsorption isotherms, and the BET isotherm confirmed the presence of multilayer adsorption. Stronger and weaker adsorption sites were suggested by using the Langmuir isotherm for the monolayer adsorption. The adsorption energies obtained from the Langmuir equation and recent spectroscopic analysis suggested that the stronger adsorption corresponded to an inner-sphere surface complex and that the weaker adsorption corresponded to outer-sphere surface complexation. The BET and Langmuir equations showed three types of adsorption mechanisms for the sulfate adsorption on the soil.

学術雑誌論文

Accepted Manuscript

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

Copyright © 2006 Elsevier Inc. All rights reserved.,© 2006. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

0021-9797