Agarose-Immobilized LTA Zeolite: a Novel Material to Use in an Improved Treatment Process of Mine-Impacted Water

Aiming to solve the difficulties inherent in the separation of adsorbents in powder form loaded with contaminant ions from treated solutions, this study presents the Linde Type A (LTA) zeolite immobilized in agarose (AG) as a new alternative outstanding adsorbent material (AG-LTA) for cation removal from mine-impacted water (MIW). Synthetic MIW containing Al 3+ , Fe 2+ , and Mn 2+ ions was tested in adsorption processes with different LTA percentages (2.34, 4.00, 8.00, 12.00, and 13.66%) immobilized in agarose. The central composite rotational design carried out indicated the optimal values of LTA dosage (8.57 g L −1 ) and agitation rate (107 rpm), with removals of 99.49, 95.55, and 95.29% for Al 3+ , Mn 2+ , and Fe 2+ , respectively, in acidic conditions. Scanning electron microscopy and spectroscopic and thermogravimetric techniques allowed the characterization of the AG-LTA material, of the ion-saturated adsorbent, and identify the ion exchange of the adsorbates Al 3+ , Fe 2+ , and Mn 2+ with the alkaline ions of LTA zeolite. Precipitation of the metal ions as hydroxides was not involved in the removal process. Experimental maximum sorption capacities of AG-LTA were 15.78, 3.02, and 19.23 mg g −1 for Al 3+ , Mn 2+ , and Fe 2+ , respectively. The high removal efficiency of the new AG-LTA adsorbent under acidic conditions may allow its use in the remediation of real MIW, complying with the stringency of environmental regulations. It is to note that AG-LTA is remarkably easy of separating from the aqueous medium after use Graphical Abstract