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Calorimetric and other interaction studies on mineral—starch adsorption systems

Authors
Journal
Colloids and Surfaces
0166-6622
Publisher
Elsevier
Publication Date
Volume
8
Issue
4
Identifiers
DOI: 10.1016/0166-6622(84)80127-4
Disciplines
  • Chemistry

Abstract

Abstract Studies have been made on adsorbabilities of starch, phosphorylated starch and starch constituents — amylose and amylopectin — on hematite and also calcite. The adsorption process is slow, partially irreversible, non-physical and appreciably exothermic. For a small starch concentration, Δ H on hematite reaches a maximum of 314 J/g starch adsorbed, and then falls off at higher concentration, probably due to partial deanchorage and reorientation of adsorbed molecules initially lying flat on the surface. Adsorption isotherm patterns, including pH-dependence behaviour, are similar for starch and amylopectin. The magnitude of adsorption of amylose, compared to that of amylopectin (nearly 20 times bulkier), is larger on a molar basis but smaller on a g/cm 2 basis. Thus, interpretation of calcite—starch adsorption data should be made in terms of amylose as well as amylopectin. For the hematite—starch system, adsorption of amylopectin is of crucial importance. Conductometric data and IR spectrograms point to specific chemical interactions between starch constituents and ions such as Fe 2+ and Ca 2+. These are evidence of the existence of chemisorption bonds of amylose as well as of amylopectin interacting on calcite and hematite surfaces.

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