The destruction of methylphosphonic acid (MPA), a final product by hydrolysis/neutralization of organophosphorus agents such as sarin and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothionate), was investigated in a a bench-scale, continuous concentric vertical double wall reactor under supercritical water oxidation condition. The experiments were conducted at a temperature range of 450-600 degrees C and a fixed pressure of 25 MPa. Hydrogen peroxide was used as an oxidant.
View Article and Find Full Text PDFThis study examined the synthesis of biodiesel using supercritical or subcritical methanol with metal oxide catalysts. The transesterification of rapeseed oil was carried out with the metal oxide catalysts (SrO, CaO, ZnO, TiO(2) and ZrO(2)) to determine the most effective heterogeneous catalyst having the highest catalytic activity with minimum weight loss caused by dissolution. SrO and CaO dissolved in the biodiesel during the reaction because they were transformed to strontium methoxide and calcium methoxide, respectively.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
December 2009
Continuous catalytic hydrodechlorination of polychlorinated biphenyls (PCBs) in the presence of transformer oils was carried out in a fixed bed reactor using a 57.6 wt% Ni on silicon oxide-aluminum oxide (SiO(2)-Al(2)O(3)) catalyst. Reaction temperatures ranging 150-300 degrees C, PCBs concentrations ranging 50-200 ppm, and reaction times ranging 1-8 h were tested.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
April 2009
Catalytic hydrodechlorination of polychlorinated biphenyls (PCBs) in the presence of transformer oil was carried out in a batch mode to detoxify PCBs and to recycle the treated oil. Various metal supported catalysts, including 0.98 wt% Pt, 0.
View Article and Find Full Text PDFA new supercritical water oxidation process for the simultaneous treatment of mixed wastewater containing wastewater from acrylonitrile manufacturing processes and copper-plating processes was investigated using a continuous tubular reactor system. Experiments were carried out at temperatures ranging from 400 to 600 degrees C and a pressure of 25 MPa. The residence time was fixed at 2s by changing the flow rates of feeds, depending on reaction temperature.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
December 2007
The oxidation rate of pentachlorophenol, [C(6)HCl(5)O] which is used to control termites and as a general herbicide and also as the probable human's carcinogen, was investigated in an isothermal continuous tubular reactor under supercritical water oxidation (SCWO) conditions. The experiments were conducted at a temperature of 400-550 degrees C and a fixed pressure of 25 MPa, with a residence time that ranged from 6 s to 26 s. The conversion of PCP was monitored by analyzing total organic carbon (TOC) on the liquid effluent samples.
View Article and Find Full Text PDFHydrothermal decomposition of pentachlorophenol (PCP, C6HCl5O), as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide (NaOH) addition. The experiments were conducted at a temperature range of 300-420 degrees C and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.
View Article and Find Full Text PDFJ Environ Sci (China)
December 2007
The destruction of toxic organic wastewaters from munitions demilitarization and complex industrial chemical clearly becomes an overwhelming problem if left to conventional treatment processes. Two options, incineration and supercritical water oxidation (SCWO), exist for the complete destruction of toxic organic wastewaters. Incinerator has associated problems such as very high cost and public resentment; on the other hand, SCWO has proved to be a very promising method for the treatment of many different wastewaters with extremely efficient organic waste destruction 99.
View Article and Find Full Text PDFExperimental autoimmune uveitis (EAU) is a well-known animal model of posterior uveitis that is one of the major causes of blindness. EAU could be induced in susceptible animals (i.e.
View Article and Find Full Text PDFA new design of supercritical water oxidation (SCWO) bench-scale reactor has been developed to handle high-risk wastes resulting from munitions demilitarization. The reactor consists of a concentric vertical double wall in which SCWO reaction takes place inside an inner tube (titanium grade 2, non-porous) whereas pressure resistance is ensured by a Hastelloy C-276 external vessel. The performances of this reactor were investigated with two different kinds of chemical warfare agent simulants: OPA (a mixture of isopropyl amine and isopropyl alcohol) as the binary precursor for nerve agent of sarin and thiodiglycol [TDG, (HOC(2)H(4))2S] as the model organic sulfur heteroatom.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
September 2006
The destruction of OPA from munitions demilitarization has been accomplished in supercritical water oxidation (SCWO) with oxygen as oxidant in an isothermal continuous-flow reactor. The experiments were conducted at a temperature of 689-887 K and a fixed pressure of 25 MPa, with a residence time that ranged from 7 s to 14 s. The destruction efficiency was measured by total organic carbon (TOC) conversion.
View Article and Find Full Text PDFSupercritical water oxidation (SCWO) has been drawing much attention due to effectively destroy a large variety of high-risk wastes resulting from munitions demilitarization and complex industrial chemical. An important design consideration in the development of supercritical water oxidation is the information of decomposition rate. In this paper, the decomposition rate of dimethyl methylphosphonate (DMMP), which is similar to the nerve agent VX and GB (Sarin) in its structure, was investigated under SCWO conditions.
View Article and Find Full Text PDFSupercritical water oxidation can effectively destroy a large variety of high-risk wastes resulting from munitions demilitarization and complex industrial chemical. An important design consideration in the development of supercritical water oxidation is the information on the oxidation rate. In this paper, the oxidation rate of isopropyl amine (OPA), one of high-risk wastes resulting from munitions demilitarization, was investigated under supercritical water oxidation (SCWO) conditions in an isothermal tubular reactor.
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