Effects of pH and ionic strength on zinc sorption by a variable charge soil

• Published in: Communications in soil science and plant analysis 2005-01, Vol.35 (15-16), p.2087-2095
• Main Authors: Casagrande, J.C, Alleoni, L.R.F, Camargo, O.A. de, Arnone, A.D
• Format: Article
• Language: English
• Subjects: Acric; Adsorption; Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Ionic strength; soil pH; Soil science; sorption isotherms; variable charge soils; Zinc
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1081/LCSS-200028914

Ionic strength and pH influence the adsorption of cations due to the variation of the electric charge in soils rich in iron (Fe) and aluminum (Al) oxides and hydroxides. The objective of this study was to investigate the influence of pH and ionic strength on zinc (Zn) sorption in a highly weathered Brazilian soil. The equations of Langmuir and Freundlich were adjusted to describe the adsorption. Zinc adsorption increased with the elevation of the pH and with the decrease of the ionic strength. The pH effect, however, surpassed the effect of the ionic strength. The largest variation of adsorption with pH suggests the presence of high-affinity adsorption sites. Langmuir and Freundlich equations were well fitted to zinc adsorption at all pH and ionic strength values. At all ionic strength and pH values, maximum adsorption in the surface layer, with negative balance of charge, was higher than in the subsoil, wherein the zero point of salt effect was higher than the soil pH in CaCl2.