Alginate-based attapulgite foams as efficient and recyclable adsorbents for the removal of heavy metals.

Floatable and porous foam adsorbents constructed by encapsulating attapulgite (ATP) in sodium alginate (SA) were fabricated via a freeze-drying and post cross-linking method, and both attapulgite and sodium alginate possessed adsorptive sites. These adsorbents were characterized by XRD, FTIR, and SEM to investigate their crystal structures, surface properties, size and morphology. In the adsorption tests, the adsorption capacity was derived from the Langmuir isotherm model, and the maximal adsorption capacity of as-prepared adsorbents was 119.0 mg g for Cu(II) and 160.0 mg g for Cd(II). In addition to the remarkable adsorptive performances, these adsorbents presented strong chemical stability and were readily recyclable because of their floatability in water solution. These aforementioned advantages highlight that the alginate-encapsulated attapulgite foams are potential scalable adsorbents for heavy metal ions removal from polluted water, and such a structure design could intrigue the development of novel adsorptive materials.