Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption

ABSTRACT Intrinsic equilibrium constants for 22 representative Brazilian Oxisols were estimated from a cadmium adsorption experiment. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. Intrinsic equilibrium constants were optimized by FITEQL and by hand calculation using Visual MINTEQ in sweep mode, and Excel spreadsheets. Data from both models were incorporated into Visual MINTEQ. Constants estimated by FITEQL and incorporated in Visual MINTEQ software failed to predict observed data accurately. However, FITEQL raw output data rendered good results when predicted values were directly compared with observed values, instead of incorporating the estimated constants into Visual MINTEQ. Intrinsic equilibrium constants optimized by hand calculation and incorporated in Visual MINTEQ reliably predicted Cd adsorption reactions on soil surfaces under changing environmental conditions.

Bibliographic Details

Main Authors:	Marchi,Giuliano, Vilar,Cesar Crispim, O’Connor,George, Oliveira,Letuzia Maria de, Reatto,Adriana, Rein,Thomaz Adolph
Format:	Digital revista
Language:	English
Published:	Sociedade Brasileira de Ciência do Solo 2015
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000501395
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