STUDY ON THE EFFECT OF HUMIC ACID ON THE ADSORPTION AND DESORPTION OF PHOSPHATE ON ACIDIC MINERAL SOIL USING SEMIEMPIRICAL PM3 METHOD
<p>Study on the effect of humic acid on the adsorption and desorption of phosphate on acidic mineral soil using semiempirical PM3 method has been done. Model construction, conformation optimization, chemical interactions study and semi-empirical PM3 calculations were performed using the HyperC...
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[Yogyakarta] : Fak. MIPA Universitas Gadjah Mada
2007
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| Summary: | <p>Study on the effect of humic acid on the adsorption and desorption of phosphate on acidic mineral soil using semiempirical PM3 method has been done. Model construction, conformation optimization, chemical interactions study and semi-empirical PM3 calculations were performed using the HyperChemTM software release 7.52. Activation energy of reaction was calculated as energy difference between energy of reactant and transition state. All the transition state searching were performed by transition search tool that available in HyperChem. The results showed that Ea of adsorption of phosphate on Al(OH)3 is 9.40 kcal/mol, is lower than Ea for adsorption of phosphate on clay mineral model (100.91 kcal/mol). It suggestions that phosphate can be adsorbed more easily on the acidic soil than on the common neutral soil. The Ea of phosphate desorption from Al(OH)3 by humic acid is 14.89 kcal/mol, is lower than Ea of phosphate desorption from Al(OH)3 by H2O (165.48 kcal/mol). It indicates that humic acid has a ability to desorption of phosphate from acid mineral soils. The Ea of adsorption of phosphate by adsorbed humic acid on clay through bridged Al-hydroxide is 159.00 kcal/mol. The latest indicated that humic acid have lower ability to adsorb anion phosphate through bridged Al-hydroxide.</p> |
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