Competitive sorption between cadmium and chromium in Oxisol varying pH and electrolyte support

Abstract

The use of industrial waste sludge to agricultural areas is widely used in Brazil, may add toxic metals to soils. The objective was to determine the competitive sorption between metals Cd2+ and Cr3+ in sub-surface horizon of a Oxisol Typic Acrustox varying conditions of pH and the presence or absence of supporting electrolyte. Environments were evaluated: a) deionized water without supporting electrolyte, b) CaCl2.2H2O (0.01 mol L-1) as supporting electrolyte, c) CaCl2.2H2O (0.01 mol L-1) with an acid pH and d) CaCl2.2H2O (0.01 mol L-1) with an alkaline pH. Were added in 5.0 mL of soil, 50.0 mL of solution containing the toxic metal, with different concentrations, within the limits established in CONAMA Resolution 420/09. Set up the Freundlich sorption isotherms in the linear model. They were made adjustments polynomial regression between the concentrations of the levels of metals in solution by contaminant concentration in the filtered solution after equilibration. Correlation analysis was performed between the retardation factor (R) and oxides content and pH. The metal was preferentially sorbed Cr3+. The presence of supporting electrolyte and pH variation did not affect the sorption of Cd2+ and competitive Cr3+.