The Role of CEC and pH in Cd Retention from Soils of North of Iran
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Cadmium (Cd) is a critical environmental chemical in which sorption reactions control its entry into soil solution. The aim of the present study was to evaluate Cd sorption characteristics of some soils of the northern part of Iran with a wide range of physicochemical properties. Duplicates of each sample were equilibrated with solutions containing 5 to 500 mg Cd L-1 with 0.01 M CaCl2 as background solution. The quantity of Cd retention was calculated as the difference between initial and equilibrated Cd concentration. Sorption isotherms including Freundlich, Langmuir, Temkin, Dubinin-Radushkevich, and Redlich-Peterson were used to evaluate the behavior of Cd sorption. Cadmium sorption data were well fitted to Langmuir, Freundlich, and Redlich- Peterson isotherms. The constant of Freundlich equation (kF) and adsorption maxima (bL) of Langmuir equation were related to pH and cation exchange capacity (CEC). The maximum buffering capacity (Kd) was significantly correlated with pH (R2 = 0.52, p = 0.001) and calcium carbonate equivalent (CCE) (R2 = 0.63, p = 0.001). Redlich-Peterson constants (kRP and aRP)were significantly correlated with pH (R2 kRP = 0.30, p = 0.007) and (R2 aRP = 0.27, p = 0.012). It seemed that pH, CEC, and CCE were the main soil properties regulating Cd retention behavior of the studied soils.
Soil and Sediment Contamination: An International Journal
© 2011 Taylor & Francis. This is an electronic version of an article published in Soil and Sediment Contamination, Vol. 20(8), 2011, pp. 908-920. Soil and Sediment Contamination is available online at: http://www.tandfonline.com with the open URL of your article.
Soil Chemistry (excl. Carbon Sequestration Science)