Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 525673
Title The interaction of certain inorganic anions with clays and soils
Author(s) Haan, F.A.M. de
Source University. Promotor(en): G.H. Bolt. - Wageningen : Pudoc - 167
Publication type Dissertation, internally prepared
Publication year 1965
Keyword(s) bodem - bodemkunde - ionenuitwisseling - soil - soil science - ion exchange
Categories Soil Chemistry
Abstract Interaction between anions and soil colloids was governed by 2 antagonistic processes, anion exclusion and positive anion adsorption. The predominantly negative charge on the colloids caused anion repulsion; positively charged sites and chemisorption resulted in positive adsorption.

Experimentally determined adsorption was the resultant of the 2 processes and yielded true net adsorption by correction for continuous anion exclusion.

Assuming the Gouy Chapman theory of the electric double layer, de Haan calculated exclusion as the apparent distance from the colloid surface free from anions of different valency. The method was valid for systems containing monovalent and divalent cations and anions with an approximation for trivalent anions, and was extended to interacting double layers.

The product of apparent distance of exclusion and of the colloid's specific surface was the volume of exclusion (V ex ), the same as the experimental adsorption value. Thus anion exclusion measurements yielded values for the colloid's specific surface. V ex was determined by a tracer method for Cl -, S0 42-, and P0 43-, and by potentiometric titration for Cl -. Adsorption of different anions could be determined simultaneously.

Theoretical derivations were confirmed in experiments with fairly pure clays and in 12 Dutch soils, with special attention to phosphate adsorption. The correction for anion exclusion allowed refined measurements of anion adsorption and explained the bonding mechanisms between anions and soil colloids.

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