Effect of Equilibrium Solution Ionic Strength on the Adsorption of Zn, Cu, Cd, Pb, As, and P on Aluminum Mining By-Product

This study evaluated the effect of the soil solution ionic strength (IS) on the adsorption of Zn, Cu, Cd, Pb, As, and P on aluminum mining by-product (AMB), as well as performed the toxicity characteristic leaching procedure test (TCLP) followed by semi-total digestion in order to evaluate whether the adsorbed elements can cause environmental health risks. We measured adsorption by reacting the adsorbent with Zn, Cu, Cd, Pb, As, and P solutions in low IS (47 mmol L-1) and high IS (470 mmol L-1). Subsequent cation and anion desorption was evaluated by adding electrolyte solutions to the remaining adsorption residue. After the desorption experiment, we performed the TCLP test followed by semi-total digestion. Changing the IS interfered on Zn, Cd, Cu, and As adsorption, while no effect was observed for Pb and P. Increasing IS decreased the desorbed amounts of Cd, Zn, Cu, and As. Among the studied elements, Cd and Zn were noteworthy for having adsorbed the least and desorbed the most. Disposal of the AMB after being used as adsorbent of Cd, Pb, and As has to be carefully made as it may present their contents above the concentration causing toxicity.