The Adsorption Behavior of Cu 2+ and Cd2+in Soils and Soils Amended with Different Organic Agricultural Waste Substances.

Adsorption of Cu²⁺ and Cd²⁺ in three soils of different physical and chemical properties was investigated (K1, K7, and Aj). The effect of amending the soils with organic agricultural waste substances (pomegranate peel and date-palm stems and leaves) on the sorption behavior of Cu²⁺ and Cd²⁺ was also investigated. The relevant soil properties included organic carbon content, calcium carbonate content, texture, cation exchange capacity, iron oxides content, clay types and contents. Cadmium initial concentration of up to 150 mg /L and copper initial concentration up to 175 mg/L were used in the sorption experiments of unamended soils, while the highest initial concentrations with the amended soils were 200 mg /L and 600 mg /L for Cu²⁺ and Cd²⁺, respectively . The results showed that copper and cadmium sorption by soils increased with the initial concentration. The sorption data conformed well to Langmuir model, with R² values above 0.97. The q_max for cadmium sorption by the three soils were 4.18, 4.45, and 3.68 mg/g; and for copper the q_max were 3.95, 4.18, and 4.29 mg/g. The effect of amendments on the sorption of Cu²⁺ and Cd²⁺ was different in the three soils.