Pollutant Adsorbent Systems for TNT, RDX and HMX in Wastewater

SIlica gels were prepared in the presence and absence of the pollutants TNT, RDX, and HMX (separately), and purified by exhaustive elution with methanol and acetonitrile. Gels prepared in the presence of TNT or RDX consistently showed enhanced adsorptive power for the homologous pollutant. The same was not true with HMX because of its very limited solubility. These gels, when their hydroxyl groups were capped with trimethylchlorosilane, exhibited the same higher adsorptive power. The relative adsorptive power (selective/control) was less than 2. Thus, the adsorption was still too small for practical use in detection or removal of these pollutants from wastewater. Cross linked acrylic polymers were similarly prepared in the presence of TNT, RDX, and HMX. These new polymers did not show any trend of increased adsorption in the case of TNT and RDX, perhaps because of high chain transfer and inhibitive properties of TNT and RDX in the free radical polymerization. However, HMX modified cross-linked polyacrylates did show a reasonable increase in adsorptivity over the normal control cross linked polymer.