Reusable adsorbents for dilute solution separation 3. Sorption dynamics ofphenanthrene on surfactant-modified alumina

The formation of surfactant aggregates (hemi-micelles) on alumina substanti ally increased the adsorption and retarded the breakthrough of a hydrophobi c organic compound (phenanthrene) in a laboratory-scale column through adso lubilization. The adsorption waves of both surfactant (sodium dodecylsulfat e, SDS) and phenanthrene were predicted adequately by existing models. Howe ver, the desorption wave was not predicted satisfactorily. The maximum capa cities of the alumina bed for both SDS and phenanthrene were determined and compared with batch adsorption isotherm data; the values were in good agre ement. The regeneration of the alumina bed was done by adjusting the feed s olution pH to higher values than during the adsolubilization step; three re generation cycles were studied. The capacities of alumina for phenanthrene and SDS sorption were found to be the same in all three cases, indicating n o significant deterioration of the alumina surface. These characteristics m ake the process of adsolubilization attractive for concentration of dilute aqueous waste streams. (C) 1999 Elsevier Science B.V. All rights reserved.