Clay Coating Systems for Removal of Heavy Metals for Waste Water

Wednesday, 4 October 2017
National Harbor 10 (Gaylord National Resort and Convention Center)
D. Blersch (Biosystems Engineering, Auburn University), M. Beidaghi (Auburn University), and E. Davis (Materials Engineering, Auburn University)
Algae turf scrubbers and other biological methods to purify polluted waters hold promise for simultaneously removing excess nutrients and producing a potentially valuable biomass crop. The harvested biomass can be used for fuel production, animal feed, or in some cases a direct food source. However, when applied to industrial waste waters contaminated with heavy metals such as lead, cadmium, and chromium VI the use of the biomass is limited. Thus, a system to remove heavy metals from these waters prior to biological filtration is required. In an industrial setting, several methods are applied for the removal of heavy metals including membrane filtration, electrolytic reduction, and ion-exchange reactions. Adsorption methods are particularly attractive owing to the possibility of regeneration and reuse. Halloysite nanotubes, a weathered smectite clay, have been investigated for adsorption of several heavy metals. Here we propose the use of a crosslinked Halloysite network for the adsorption of heavy metals from waste streams. A thermally reversible Diels-Alder reaction scheme is used to crosslink Halloysite nanotubes and allows for the system to be cast into multiple configurations such as coating and porous membranes with high Halloysite loadings. Halloysite nanotubes were modified with 3-(2-Furyl)propanoic acid or 11-maleimido-undecanoic acid. Mixtures of these materials were solution cast resulting in crosslinked Halloysite films and membranes. These systems were evaluated for heavy metal adsorption capacity and rate.