Degradation of Organic Pollutants

From laboratory to plant, the commercially available Ti02 named Degussa P-25 (30 nm) has been widely used in the treatment of contaminated water, and has indeed become a research standard reference [9, 10]. This two-phase composite (anatase and rutQe) has been considered to have a synergy effect for photocatalytic reactions [11]. 

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The oxidative degradation of organic pollutants in water and air streams is considered as one of the so-called advanced oxidation processes. Photocatalytic decomposition of organics found widespread industrial interest for air purification (e.g., decomposition of aldehydes, removal of NO , ), deodorization, sterilization, and disinfection. Domestic applications based on Ti02 photocatalysts such as window self-cleaning, bathroom paints that work under illumination with room light, or filters for air conditioners operating under UV lamp illumination have already been commercialized. Literature-based information on the multidisciplinary field of photocatalytic anti-pollutant systems can be found in a number of publications, such as Bahnemann s [237, 238] (and references therein). 

Anandan S, Ashokkumar M (2009) Sonochemical synthesis of Au-Ti02 nanoparticles for the sonophotocatalytic degradation of organic pollutants in aqueous environment. Ultrason Sonochem 16 316-320... 

Wu, Y., Zhang, J., Xiao, L., and Chen, F. (2009) Preparation and characterization of Ti02 photocatalysts by Fe3+ doping together with Au deposition for the degradation of organic pollutants. Applied Catalysis B Environmental, 88 (3—4), 525—532. 

Patsoura, A., Kondarides, D.I., and Verykios, X.E. (2007) Photocatalytic degradation of organic pollutants with simultaneous production of hydrogen. Catalysis Today, 124 (3-4), 94-102. 

This section covers environmental applications of nanomaterials insofar as they are directly applied to the pollutant of interest. The photocatalytic degradation of organic pollutants and remediation of polluted soils and water are discussed here. The high surface areas and photocatalytic activities of semiconductor nanomaterials have attracted many researchers. Semiconductor nanomaterials are commercially available, stable, and relatively nontoxic and cheap. Prominent examples that are discussed are metal oxides such as Ti02 and ZnO and a variety of Fe-based nanomaterials. 

The following section discusses the different types and phases of microbial degradation of organic pollutants present at aqueous-solid phase interfaces. This includes a discussion of growth-linked biodegradation, acclimation, detoxification, activation, defusing, threshold, and co-metabolism. 

Wang, P., et al., A one-pot method for the preparation of graphene-Bi2Mo06 hybrid photocatalysts that are responsive to visible-light and have excellent photocatalytic activity in the degradation of organic pollutants. Carbon, 2012. 50(14) p. 5256-5264. 

Radionuelides can be also used to study the accumulation and degradation of organic pollutants. In our experiments we have followed the uptake and degradation of labelled TNT by wetland plants (Nepovim et al., 2005), and showed that about 63% of the localized in the roots of Ph. australis was bound (Fig. 6) and the remainder was acetone-extractable. An HPLC analysis of the acetone extract failed to detect any TNT, showing that all TNT had been chemically transformed. Thus TNT was not adsorbed on the root surface. In similar experiments performed in wheat (Triticum aestivum). Sens et al. (1999) found that 57% of the taken up was bound... 

Ranjit, K.T., Cohen, H., Willner, I., Bossmann, S., Braun, A. 1999. Lanthanide oxide-doped titanium dioxide effective photocatalysts for the degradation of organic pollutants. J Mater Sci 34 5273-5280. 

Brillas, E Cabot, P-L Casado, J. Electrchemical methods for degradation of organic pollutants in aqueous media. In Tarr MA, editor. Chemical degradation methods for wastes and pollutants - environmental and industrial applications. New York Marcel Dekker 2003 235-304. 

Rosales E, Pazos M, Longo MA. Sanroman, MA. Influence of Operational Parameters on Electro-Fenton Degradation of Organic Pollutants from Soil. Journal of Environmental Science and Health. Part A 2009 44 1104-1111. 

You work in a research laboratory and your job is to investigate the microbial degradation of organic pollutants in laboratory aquifer column systems. You supply a column continuously with a synthetic groundwater containing 0.3 mM 02, 0.5 mM NOj, 0.5 mM SO -, and 1 mM HCOj, as well as 0.1 mM benzoic acid butyl ester, which is easily mineralized to C02 and H20. The temperature is 20°C and the pH is 7.3 (well buffered). Would you expect sulfate reduction or even methanogenesis to occur in this column Establish an electron balance to answer this question. 

TABLE 2 Variables and Experimental Region" for the Investigation of the Pilot Level Ti02 Photocatalyzed Oxidative Degradation of Organic Pollutants Contained in an Industrial Waste Water [12]... 

Because AOPs take advantage of the high reactivity of hydroxyl radicals, initial, propagation, promotion, recombination, and reversible reactions are commonly involved in the degradation of organic pollutants. Table 4.3 lists these major elementary reactions. 

Reactions in the Degradation of Organic Pollutants by Various AOPs ... 

In Fe(II)/H202 acid media, oxidation occurs via hydroxyl radical. The use of ultraviolet in both cases results in the generation of HO radicals, formed by the reaction of Fe(II) with H202. In ferrioxalate systems, this reaction occurs after photolysis by photons with wavelengths less than 450 nm therefore, it plays a significant role in the degradation of organic pollutants in natural water, due to solar irradiation. 

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