la5b01084_si_001.pdf (690.78 kB)
Confined Flocculation of Ionic Pollutants by Poly(l‑dopa)-Based Polyelectrolyte Complexes in Hydrogel Beads for Three-Dimensional, Quantitative, Efficient Water Decontamination
journal contribution
posted on 2015-06-16, 00:00 authored by Li Yu, Xiaokong Liu, Weichang Yuan, Lauren Joan Brown, Dayang WangThe
development of simple and recyclable adsorbents with high adsorption
capacity is a technical imperative for water treatment. In this work,
we have successfully developed new adsorbents for the removal of ionic
pollutants from water via encapsulation of polyelectrolyte complexes
(PECs) made from positively charged poly(allylamine hydrochloride)
(PAH) and negatively charged poly(l-3,4-dihydroxyphenylalanine)
(PDopa), obtained via the self-polymerization of l-3,4-dihydroxyphenylalanine
(l-Dopa). Given the outstanding mass transport through the
hydrogel host matrixes, the PDopa-PAH PEC guests loaded inside can
effectively and efficiently remove various ionic pollutants, including
heavy metal ions and ionic organic dyes, from water. The adsorption
efficiency of the PDopa-PAH PECs can be quantitatively correlated
to and tailored by the PDopa-to-PAH molar ratio. Because PDopa embodies
one catechol group, one carboxyl group, and one amino group in each
repeating unit, the resulting PDopa-PAH PECs exhibit the largest capacity
of adsorption of heavy metal ions compared to available adsorbents.
Because both PDopa and PAH are pH-sensitive, the PDopa-PAH PEC-loaded
agarose hydrogel beads can be easily and completely recovered after
the adsorption of ionic pollutants by adjusting the pH of the surrounding
media. The present strategy is similar to the conventional process
of using PECs to flocculate ionic pollutants from water, while in
our system flocculation is confined to the agarose hydrogel beads,
thus allowing easy separation of the resulting adsorbents from water.