Degradation of alkylphenolic compounds in aqueous media by fenton and ultraviolet induced fenton reaction

In this paper, we studied Fenton and photo-Fenton-advanced oxidation processes for degradation of alkylphenolic compounds under various experimental conditions. Bisphenol A (BPA) has been degraded more slowly than 3,5-dimethylphenol (3,5-DMP) and 2,5-dimethylphenol (2,5-DMP), but faster than 2,4,6-trimethylphenol (2,4,6-TMP) under the same experimental conditions (ratios of Fe2+/Organic Substrate-2, H2O2/Organic Substrate=14). Mineralization rate of BPA was increased by irradiation of Fenton reagent with UV light (photo-Fenton, 40 W UV lamp), and 89% of mineralization was achieved for 700 ml solutions, while only 63% mineralization was observed in absence of UV-light (Fenton) at 250 min reaction times. Considerable excess of H2O2 in reaction medium caused decreases in mineralization efficiency, due to scavenging the hydroxyl radicals generated in Fenton and photo-Fenton reactions. The efficiency of the degradation was improved by loading H2O2 into reaction medium in small amounts at various time intervals. © by PSP 2006

A comparative study of ozonation, homogeneous catalytic ozonation, and photocatalytic ozonation for C.I. Reactive Red 194 azo dye degradation

In this study, the decolorization, dearomatization, and mineralization efficiencies of different advanced oxidation processes (AOPs; namely O 3, O 3/Fe(II), O 3/Fe(II)/UVA, and O 3/TiO 2/UVA) were investigated for the azo dye C.I. Reactive Red 194 (RR194). The effects of pH (3-11), amount of TiO 2 (0.05-1g/L), and concentration of Fe(II) (0.1-1.6mM) were investigated for the applied methods. The decolorization and mineralization efficiencies of the photocatalytic ozonation system (O 3/TiO 2/UVA) were increased by decreasing the pH of the dye solution in contrast to the ozonation system (O 3). Decolorization of RR194 was increased in the photocatalytic ozonation system with an increasing amount of catalyst however, a decreasing was occurred for the homogeneous catalytic system (O 3/Fe(II)) when increasing the concentration of catalyst. The decolorization efficiency of the homogeneous catalytic system (O 3/Fe(II)) was enhanced when combined with UVA light. In our study, the most efficient method for dearomatization and mineralization was the O 3/TiO 2/UVA among the applied AOPs. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Comparison of the fatty acid composition of the freshwater fish larvae Tilapia zillii, the rotifer Brachionus calyciflorus, and the microalgae Scenedesmus abundans, Monoraphidium minitum and Chlorella vulgaris in the algae-rotifer-fish larvae food chains

The proximate and the fatty acid analysis of the warm freshwater fish, Tilapia zillii larvae, the freshwater rotifer Brachionus calyciflorus and the microalgae Scenedesmus abundans, Monoraphidium minitum and Chlorella vulgaris each constituting a different food chain with B. calyciflorus and T. zillii larvae have been carried out. C. vulgaris had significantly higher lipid content than the other two microalgae and this was also reflected in the lipid content of B. calyciflorus fed each of the microalgae separately. Five fatty acids dominated in all the microalgae, namely 18:3n - 3, 18:2n - 6, 18:0, 18:1 and 16:0 though there were significant differences both in quantitative distribution of these acids and the total fatty acid content. The content of 18:3n-3, 18:2n-6 and 16:0 and the total fatty acid content of C. vulgaris were considerably higher than the corresponding values in the other two microalgae. But interestingly, these strong differences were not reflected in B. calyciflorus samples fed these microalgae separately though the one fed C. vulgaris had slightly higher total fatty acid content than the other two rotifer samples. One can consider that the freshwater rotifer B. calyciflorus is capable of creating its own characteristic fatty acid content up to a sufficient level even when cultured with a fatty acid deficient algae probably by consuming excessive amounts of this algae compared to other algae of relatively high fatty acid content. The proximate and fatty acid analysis results of the three T. zillii larvae fed the three B. calyciflorus samples obtained by culturing with three different microalgae were very similar. This was an expected result because the three B. calyciflorus samples did not differ much from each other. The low 18:2n - 6 (1.66-3.53 mg g-1 DM) and 18:3n - 3 (1.14-1.22 mg g-1 DM) content and the relatively high 22:6n - 3 (10.7214.38 mg g-1 DM) content of the T. zillii larvae samples indicated that they were capable of elongating and desaturating both linoleic and linolenic acids of the B. calyciflorus samples

Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study

We investigated a new adsorbent system, Reactive Red 120 attached poly(2-hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA-EDMA)] beads, for the removal of Ni2+ ions from aqueous solutions. Poly(HEMA-EDMA) beads were prepared by the modified suspension copolymerization of 2-hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150-250 µm), having a swelling ratio of 55% and carrying 25.5 µmol of Reactive Red 120/g of polymer, were used in the removal of Ni2+ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA-EDMA) beads for Ni2+ ions was investigated in aqueous media containing different amounts of Ni2+ ions (5-35 mg/L) and having different pH values (2.0-7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni2+ ions onto the Reactive Red 120 attached poly(HEMA-EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni2+ ions onto poly(HEMA-EDMA) beads was negligible (0.1 mg/g). The desorption of Ni2+ ions was studied with 0.1M HNO3. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k20°C = 0.565 mg/g min0.5, k30°C = 0.560 mg/g min 0.5, and k40°C = 0.385 mg/g min0.5. Adsorption-desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo-first-order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc