A method for the removal of ethylenediaminetetraacetic acid (EDTA) at room temperature and 1 atm is demonstrated. EDTA (1 mM, 50 mL) containing 2.5 g of granular zerovalent iron (ZVI) (20-40 mesh) was degraded in 2.5 h. Using a recently developed form of O2 activation, reactive oxygen species are generated in situ, resulting in the degradation of EDTA when complexed with FeII. ESI-MS measurements indicate that degradation of EDTA yields low-molecular carboxylic acids. The presence of oxygen is crucial: the observed pseudo-first-order rate constants for EDTA removal are kobs = 1.02 h(-1) (kSA = 1.85 +/- 0.046 L h(-1) m(-2)) and kobs = 0.04 h(-1) (kSA = 0.00724 +/- 0.002 L h(-1) m(-2)) under air and under N2 purge, respectively. kSA represents surface area normalized rate constants. Large excesses of EDTA in the reaction mixture slowthe rate of degradation. Increasing the concentration of EDTA from 1.0 to 10.0 mM while holding all other parameters constant gave observed rates of kobs = 1.02 +/- 0.26 h(-1) (kSA = 1.85 +/- 0.046 L h(-1) m(-2)) and kobs = 0.044 +/- 0.01 h(-1) (kSA = 0.00796 +/- 0.002 L h(-1) m(-2)), respectively. The rate-limiting step is determined to be homogeneous oxygen activation.

The complete destruction of separate mixtures of 1.1 mM 4-chlorophenol (aqueous) and 0.61 mM pentachlorophenol (aqueous slurry) take place in the presence of 0.5 g of iron particles in 10 mL of 0.32 mM ethylenediaminetetraacetic acid (EDTA) under ambient air under room temperature conditions. Under this reaction condition, the time required to reach complete disappearance to the detection limit of GC-FID for each compound was 4 h for 4-chlorophenol and 70 h for pentachlorophenol. Electrospray ionization mass spectral (ESI-MS) analysis of the 4-chlorophenol reaction mixture after its complete disappearance indicated non-chlorinated, primarily low molecular weight products; however, Clfrom 4-chlorophenol was not detected due to adsorption onto the iron or its corrosion products. Radical trap and control experiments suggest that the mechanism for destruction initiates with dioxygen activation, leading to the formation of reactive oxygen species (ROS) and ultimately ring opening of the phenolic compounds. This is the first example of an abiotic system capable of the complete destruction of an organic pollutant under room temperature and pressure conditions through dioxygen activation chemistry.

The organophosphorus insecticide malathion was selected as an analog for the chemical nerve agent, VX. Degradation of 0.44 mM malathion in a 10 mL aqueous solution containing 0.50 g granular zero valent iron (ZVI) under ambient air and pressure was complete after 4 h to the detection limit of GC-FID. The degradation kinetics demonstrate the system to be pseudo-first-order with respect to malathion disappearance with a rate constant of 0.92 h 21 . The only non-polar organic intermediates detected were diethyl succinate and malaoxon, of which malaoxon is degraded to below the limit of detection of the GC-FID after 12 h. Electrospray ionization mass spectral analyses show the final reaction products to be low molecular weight carboxylic acids (propionic, oxalic and iminodiacetic acid).

Three palladium-catalyzed zerovalent metal systems were found to be able to hydrogenate phenol to cyclohexanol and cyclohexanone under room temperature and pressure conditions. Exposure of 5.0 mM aqueous phenol solutions to Pd (2.6 ppt m/m)/Mg (1.00 g 20 mesh) and to 0.53 g of 1/8 in. Pd (0.5%)/alumina in contact with 1.00 g 20 mesh Mg results in 74% and 24% destruction of the reactant after 6 h of reaction time. The latter system was found to be greatly enhanced in the presence of 2% (v/v) glacial acetic acid, resulting in an 84% reduction of phenol with a carbon balance of 93%. Palladized iron and unmodified metals systems were much less effective at hydrogenating phenol. The advantage of the 1/8 in. Pd/alumina/20 mesh Mg system is that it gives a readily recoverable form of the catalysts when compared to the bimetallic systems.