Surface Complexation Modeling in Variable Charge Soils: Charge Characterization by Potentiometric Titration

Revista Brasileira de Ciência do Solo

Giuliano Marchi¹  Cesar Crispim Vilar¹  George O’connor¹  Marx Leandro Naves Silva¹ 

关键词: intrinsic equilibrium constants;    Oxisols;    FITEQL;    Visual MINTEQ;    chemical equilibrium software;    constantes de equilíbrio intrínsecas;    Latossolos;    FITEQL;    Visual MINTEQ;    programa de equilíbrio químico;   

DOI  :  10.1590/01000683rbcs20140528

来源: SciELO

【 摘 要 】

ABSTRACT Intrinsic equilibrium constants of 17 representative Brazilian Oxisols were estimated from potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in suspensions of varying ionic strength. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. The former was fitted by calculating total site concentration from curve fitting estimates and pH-extrapolation of the intrinsic equilibrium constants to the PZNPC (hand calculation), considering one and two reactive sites, and by the FITEQL software. The latter was fitted only by FITEQL, with one reactive site. Soil chemical and physical properties were correlated to the intrinsic equilibrium constants. Both surface complexation models satisfactorily fit our experimental data, but for results at low ionic strength, optimization did not converge in FITEQL. Data were incorporated in Visual MINTEQ and they provide a modeling system that can predict protonation-dissociation reactions in the soil surface under changing environmental conditions.

【 授权许可】

CC BY   
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