UTILIZING OXIDANT-DOPED GEOPOLYMERS FOR REMEDIATION OF CONTAMINATED RUNOFF: A NEW TECHNOLOGY FOR SOURCE MANAGEMENT

Contamination of urban streams by runoff containing polycyclic aromatic hydrocarbons (PAHs) remains a serious problem. Once sorbed onto solids and captured in stream sediments, remediation is often problematic. One possible approach is to treat contaminants at the source using an oxidant like KMnO₄ (potassium permanganate). Recently geopolymers have been found to be a useful material for the controlled-release of KMnO₄. Together they can be used to create an in-situ chemical oxidation filter to control PAHs at the source in urban environments. These oxidant doped filters could be retrofitted to runoff collection points such as storm water grates in parking lots, breaking down PAHs in runoff before they reach larger conduits. SEM imaging shows that geopolymers doped with KMnO₄ create a dual porosity medium consisting of the geopolymer matrix and permanganate crystals. Our experiments test whether variations in preparation technique of the doped geopolymers could provide an enhanced lifetime. Column experiments have shown that matrix density and permanganate crystal network connectivity, influences porosity and release rates of MnO₄^- through time. The analysis of several samples shows the controlling influences of factors. Results indicate that as more KMnO₄ is packed into a sample the porosity increases. As a consequence, KMnO₄ released became influenced by dissolution release in addition to diffusion. The release life-time was found to decline as a highly interconnected pore-system developed. Preliminary indications are that this slow release system has potential in the remediation of urban systems.