Photo-assisted oxidation

In other studies [34,186], the treatment of trichloroethylene and tetrachloroethylene with UV/H202 system is reported. For example, Beltran et al. [34] determined the rate constants of the reactions between hydroxyl radical and TCE and TCA with this oxidizing system at high concentration of hydrogen peroxide. Hirvonen et al. [186] observed the formation of chloroacetic acids during the hydrogen peroxide photo-assisted oxidation of tri- and tetrachloroethylene. These authors [186] report that formation of chloroacetic acids diminishes when hydrogen peroxide is simultaneously applied to UV radiation compared to UV radiation alone. 

Philippopoulos, C.J. Poulopoulos, S.G. Photo-assisted oxidation of an oily wastewater using hydrogen peroxide. J. Hazard. Mater. 2003, B98, 201-210. 

Lopez, H.H. and Martinez, A. (2002) Selective photo-assisted oxidation of methane into formaldehyde on mesoporous VOx/SBA-15 catalysts. CataL Lett, 83, 37-41. 

To further probe the mechanism of the photo-assisted oxidation of the phenolic groups by TiOi surface, absorption isotherm experiments were conducted using ammonia as the probe. Ammonia was chosen as a probe to determine the relative acidity of the pigment surface. Knowledge of the surface acidity could explain the interplay of the amine additives with the pigment surface and illuminate possible acid/base interactions between surface and amine additive. 

Sastri MVC, Nagasubramanian G (1982) Studies of ferric oxide electrodes for the photo-assisted electrolysis of water. Int J Hydrogen Energy 11 873-876... 

Pourbaix (16) has prepared theoretical stability diagrams of potential vs. pH for many common metals and nonmetalloids. A review of these results indicates that semiconductor compounds of Au, Ir, Pt, Rd, Ru, Zr, Si, Pd, Fe, Sn, W, Ta, Nb, or Ti should serve as relatively acid-stable photoanodes for the electrolysis of water. Indeed, all of the stable photo-assisted anode materials reported in the literature, as of March, 1980 (see Table III) contain at least one element from this stability list, with the exception of CdO. Rung and co-workers (18) observed that the CdO photoanode was stable at a bulk pH of 13.3. The Pourbaix diagram for Cd (16) shows that an oxide film passivates Cd over the concentration range 10.0 < pH < 13.5. Hence the desorption of the product H+ ion for the particular case of CdO must be exceptionally facile without producing an effective surface pH lower than 10.0. This anamolous behavior for CdO is not well understood. 

Evgenidou E, Konstantinou I, Fytianos K, Poulios I. Oxidation of two organophos-phorus insecticides by the photo-assisted Fenton reaction. Water Res 2007 41 2015-27. 

The degradation of aromatics, pesticides, herbicides, and other bio-recalcitrant compounds in industrial wastewaters can be efficiently achieved by means of the oxidative radicals generated in the Fenton and photo-assisted Fenton reaction [11], Among others, the photo-Fenton method has proved to be effective in the degradation of phenol and its halogenated derivatives [12-14], dioxins [15], nitroaniline [16],... 

Fig. 5.8 Examples of oxidative water treatment technologies used in industry, research and development [adapted from FIGAWA (1997), and supplemented by novel methods]. The numbers 1 to 9 refer to the generalized reaction sequences presented in Figure 5-9. a) Oxidation at elevated temperatures between 220°C < T <300°C or supercritical water oxidation at AT >374°C, Ap >221 bar (221000 kPa) (cf Chapter 1) b) oxidation in the presence of bimetallics Fe°/Ni° or Zn°/Ni° (Cheng and Wu, 2001) or heterogeneous oxidation in supercritical water catalyzed by metals Me = Cu, Ag, Au/Ag-alloy c) Fenton reaction at pH <5 d) photo-assisted Fenton reaction, irradiation in the UV-B/VIS range e) the mixture of oxidants O3/H2O2 is called PEROXONE f) ozonation using solid-bed catalysts with conditioned activated carbon (AC) g) vacuum-UV photolysis of water.

The importance of the [R-COO j as a preferred reaction pathway in the decomposition of pollutants on the surface [polyethylene-COO -Fe " ] is rationalized by the observation that these copolymer thin films should be attacked by Off, H02° and other oxidative radicals available in solution. But this was not the case for [polyethylene-COO -Fe ] even when used over long times (300 hours) and repeated recycling below the polyethylene flowing temperature (80°C). Moreover, the observation reported recently [8] that degradation of organic compounds is able to take place during Fenton photo-assisted treatment in the presence of 3000 ppm of Cl -ion... 

T.D. Waite, I.C. Wrigley, R. Szymczak (1988). Photo-assisted dissolution of a colloidal manganese oxide in the presence of fulvic acid. Environ. Sci. Technoi, 22, 778-7863. 

Table III.3. Photo-assisted catalytic oxidation of methane and ethane using silica-supported group V and VI metal oxide catalysts (493 K).

The HG-F(QF)AAS method is a widespread detector for the determination of arsenic compounds because it is inexpensive. The disadvantage of this detection is that it is restricted to hydride-forming arsenic compounds. There are numerous articles published using postcolumn UV photo-oxidation (67,80,81) or microwave-assisted oxidation (81,82) to convert the non-hydride-active arsenic compounds, such as AB, AC, and TETRA, to the hydride-active compounds. 

A number of methods have been developed for the synthesis of the Au NPs on the graphene oxide (GO)/rGO nanosheets such as chemical reduction, electrochemical deposition, photo-assisted reduction, sonochemical methods, and microwave irradiation [19-24]. 

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