(559g) Metal Organic Frameworks (MOFs) for Degrdation of Nerve Agent Simulant Parathion

Halder, R. N., US Army ERDC-CERL
Kapila, S., University of Missouri-Rolla
Bednar, A. J., US Army Engineer Research and Development Center
Paikoff, S. J., Defense Threat Reduction Agency

Parathion, a simulant of nerve agent VX, has been studied for degradation on Fe3+, Fe2+ and zerovalent iron supported on chitosan. Chitosan, a naturally occurring biopolymer derivative of chitin, is a very good adsorbent for many chemicals including metals. Chitosan is used as supporting biopolymer for forming metal-organic frameworks (MOFs). Chitosan powder was dissolved in 10% oxalic acid to make a gel. Ferric chloride or ferrous chloride solution or iron powder was added to the gel. The composite gel was formed in to beads by dropping the gel into sodium hydroxide solution using a peristaltic pump. The beads were washed, dried and cross-linked using glutarldehyde. Sorption and degradation of parathion in aqueous solutions were experimentally studied in the present work in batch mode as well as in continuous flow mode using all the three forms of iron supported chitosan beads.  Batch studies were performed in vials with chitosan-iron MOFs beads and known volume of the simulant solution in water of known concentration at room temperature. The solution was allowed to react for 16 hours after which the beads were separated from the solution.  The solution was analyzed using high performance liquid chromatography (HPLC). The analysis showed that the simulant degraded. The degradation efficiency was highest when Fe3+ supported chitosan was used. Some degradation also occurred with unsupported beads, but the degradation was much less than for other forms of iron supported beads. Results from these studies also indicate that Fe3+ supported chitosan has the highest removal rate of all three forms of iron supported chitosans for all three stimulants used. Removal rates exceeding 90% were obtained. Routes of degradation were identified from the Electron Spray Ionization-Mass Spectrometry (ESI-MS) studies.