Effect of Contact time on the Capacity of Adsorptive Materials for Metal Sorption in Solution
An experiment was carried out to determine metal sorption in solution, as a primary tool for evaluating metal immobilization as a viable option in the clean up of contaminated soil. Selected organic and inorganic materials were evaluated for adsorptive capacity as well as the contact time required for optimum sorption. Single solutions of Pb, Cu and Zn were prepared from metal salts and shaken with bone meal, general purpose compost, peat, coir, wood bark and green waste compost at controlled pH and laboratory temperature. Three metal concentrations of 0.1 mmol/l, 0.5 mmol/l and 1.5 mmol/l were used, at shaking times of 15, 30, 60 and 120, 720 and 1440 minutes. Sorption capacity of each adsorptive material was determined at equilibrium, and all six materials were effective in adsorbing the three metals. Contact time for optimal sorption was 1 hour, as more than 95% of metal sorption had occurred by 60 minutes of agitation.
Keywords: heavy metal, contact time, adsorption, sorption capacity