Zinc adsorption in highly weathered soils

Pesquisa Agropecuária Brasileira

José Carlos Casagrande¹  Marcio Roberto Soares¹  Ernesto Rinaldi Mouta¹ 

[1] ,Universidade Federal de São Carlos Centro de Ciências Agrárias Departamento de Recursos Naturais e Proteção AmbientalAraras SP ,Brazil

关键词: pH;    adsorption envelope;    adsorption isotherm;    ionic strength;    trace element;    pH;    envelope de adsorção;    isoterma de adsorção;    força iônica;    elemento-traço;   

DOI  :  10.1590/S0100-204X2008000100017

来源: SciELO

【 摘 要 】

The objective of this work was to assess the effects of pH and ionic strength upon zinc adsorption, in three highly weathered variable charge soils. Adsorption isotherms were elaborated from batch adsorption experiments, with increasing Zn concentrations (0-80 mg L-1), and adsorption envelopes were constructed through soil samples reactions with 0.01, 0.1 and 1 mol L-1 Ca(NO3)2 solutions containing 5 mg L-1 of Zn, with an increasing pH value from 3 to 8. Driving force of reaction was quantified by Gibbs free energy and separation factor. Isotherms were C-, H- and L-type and experimental results were fitted to nonlinear Langmuir model. Maximum adsorption ranged from 59-810 mg kg-1, and Zn affinity was greater in subsoil (0.13-0.81 L kg-1) than in the topsoil samples (0.01-0.34 L kg-1). Zinc adsorption was favorable and spontaneous, and showed sharply increase (20-90%) in the 4-6 pH range. No effect of ionic strength was observed at pH values below 5, because specific adsorption mechanisms predominated in the 3-5 pH range. Above pH 5, and in subsoil samples, Zn was adsorbed by electrostatic mechanisms, since ionic strength effect was observed. Despite depth and ionic strength effects, Zn adsorption depends mainly on the pH.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License