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

摘要

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 immo-bilized in agarose(AG)as a new alternative outstand-ing 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 dos-age(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 thermo-gravimetric techniques allowed the characterization of the AG-LTA material,of the ion-saturated adsor-bent,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.Experimen-tal 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,comply-ing with the stringency of environmental regulations.It is to note that AG-LTA is remarkably easy of sepa-rating from the aqueous medium after use.