Environmental Chemistry Letters (v.1, #2)
Green epoxidation on Ti-mesoporous catalysts
by F. Chiker; F. Launay; J. P. Nogier; J. L. Bonardet (pp. 117-120).
New mesoporous catalysts with a mean pore size of 65 Å have been synthesised by grafting titanium on a mesoporous silica SBA15 (Santa BArbara) by means of titanium tetrachloride in the gas phase. These catalysts have been tested for the green epoxidation of cyclooctene, cyclohexene, (R)-limonene and α-pinene by hydrogen peroxide, tert-butyl hydroperoxide or cumyl hydroperoxide. The selectivity is 100% and epoxide yields can reach almost 100% in the case of organic hydroperoxides without any leaching of titanium species. Here we show that cyclohexene epoxidation could be used as the first step of a greener synthesis of adipic acid.
Keywords: Mesoporous; SBA; Titanium; Epoxidation; Hydroperoxide; Cyclohexene
Binding of trinitrotoluene (TNT) to water extractable humus
by Heike Knicker; Petra Müller (pp. 121-125).
Solid-state 15N NMR was applied to the aqueous extracts of a 13C-enriched plant slurry (Lolium perenne), anaerobically incubated with 15N3-trinitrotoluene (TNT). Almost all 15N3-TNT transformation products became covalently bound to the plant-derived organic material extractable with water. DCPMAS 15N 13C NMR revealed a three-step reaction scheme. After reduction of TNT, the aryl amines are acetylated. Subsequent alkylation of the resulting amides strengthens the incorporation of TNT-transformation products into humic material. Comparable results have been recently obtained under aerobic conditions, which indicates that this pathway is a common process during biological TNT transformation.
Keywords: Solid-state; 15N NMR; Transport of TNT; Covalent binding; Anaerobic degradation
Chloroacetic acids in environmental processes
by M. Matucha; M. Gryndler; S. T. Forczek; H. Uhlířová; K. Fuksová; P. Schröder (pp. 127-130).
The fate of chloroacetic acids (CAA) in forest soils was studied using radio-indicator methods. We showed that chloroacetic acids are both microbially degraded and simultaneously formed by chloroperoxidase-mediated chlorination of acetic and humic acids. The degree of biodegradation of chloroacetic acids in soil depends on their concentration. Dichloroacetic acid (DCA) is degraded faster than trichloroacetic acid (TCA). Chlorination of acetic acid led to a fast formation of dichloroacetic acid, whereas chlorination of humic acids gave rise to trichloroacetic acid. Both processes lead to a steady state in soil, participate in the chlorine cycle and possibly also in decomposition of organic matter in forest ecosystems.
Keywords: Dichloroacetic acid; Trichloroacetic acid; Microbial degradation; Enzymatic chlorination; Forest soil; Radio-indicator methods; Radioactively labelled compounds
Fate of the veterinary medicine ivermectin in soil
by Christian Mougin; Albert Kollmann; Jacqueline Dubroca; Paul Henri Ducrot; Michel Alvinerie; Pierre Galtier (pp. 131-134).
We investigated the fate of the drug ivermectin in the soil. We found that ivermectin was transformed solely by photos, leading to the formation of two ivermectin isomers. We indeed failed to detect any biotransformation reaction of the chemical either in the soil or in fungal liquid cultures. According to its limited water solubility, the bioavailability of ivermectin was very low in the soil solution. Here, we show that ivermectin, transferred to the soil from faeces of drug-treated cattle, could be stored for long periods in the soil.
Keywords: Avermectin; Ivermectin; Soil; Transformation; Bioavailability
Biosorption of Cr(VI) using low cost sorbents
by N. Fiol; I. Villaescusa; M. Martínez; N. Miralles; J. Poch; J. Serarols (pp. 135-139).
Waste products from industrial operations, such as yohimbe bark, grape stalks, cork and olive stones were investigated for the removal of Cr(VI) from aqueous solutions. Equilibrium batch experiments at room temperature were performed. Metal uptake showed a pH-dependent profile and optimum uptake at initial pH between 2.0–3.0. Slight influence of NaCl on metal uptake was observed. The sorption data fitted well to the Langmuir model within the concentration range studied. Grape stalks proved to be the most efficient sorbent followed by yohimbe bark, cork and olive stones.
Keywords: Yohimbe bark wastes; Cork wastes; Grape stalk wastes; Olive stone wastes; Chromium; Metal removal
Maximum uptakes of cadmium on free and immobilised bacteria and actinomycetes cells
by Bernard Fabre; K. Jézéquel; T. Lebeau (pp. 141-144).
Studies of adsorption of cadmium by free bacterial and free actinomycete cells, alginate beads and immobilised bacterial or actinomycete cells in alginate beads were performed in ultrapure water. The immobilisation in alginate beads allows the survival of the microorganisms in non-ideal conditions. Here, we found the following affinity for the cadmium ion: R25 free cells b Langmuir parameter. The maximum uptakes gave the series: ZAN 044 free cells
Keywords: Cadmium; Free and immobilised micro-organisms; Alginate beads; Linear and non-linear modelisations; Maximum uptakes
Fungal laccases: from structure-activity studies to environmental applications
by Christian Mougin; Claude Jolivalt; Pierre Briozzo; Catherine Madzak (pp. 145-148).
Laccases are multicopper oxidases mainly secreted by filamentous fungi. Producing radical forms from organic substrates, they are involved in numerous reactions leading to the degradation and polymerization of xenobiotics. Our studies have led to a better knowledge of the structural, catalytic and genetic properties of laccases and allowed to develop a strategy for their evolution through genetic engineering. Here, we show that fungal laccases, wild or engineered, may be potent tools to develop bioremediation processes of soils polluted by organic compounds, and assays to assess the ecotoxicological impact of these pollutants on soil fungi.
Keywords: Fungal laccases; Xenobiotics; Biotransformation; Bioremediation; Ecotoxicological risk assessment; Genomics; Proteomics
Effect of deuterium-depleted water on reproduction of rainbow trout
by F. Pricope; Ştefănescu; G. Tiţescu; I. Cărăuş; D. Ureche (pp. 149-151).
During the artificial reproduction of salmonides, the fecundity can be increased either by improving the viability of spermatozoa, or by extending the time period during which a roe micropile remains open, thus allowing its fecundation. Practically, this can be achieved by the use of some fertilising techniques suitable for fish species. Here, we show that the reproduction of rainbow trout in a 1:1 solution of deuterium-depleted water and distilled water led to a significant increase in survival of roes during their embryonic development. Moreover, the addition of glucose and fructose into the deuterium-depleted fertilising solutions led to a further increase in roe survival during embryonic development. The increase in survival is mainly explained by an increase in the motility of spermatozoa.
Keywords: Salmonids; Artificial reproduction; Deuterium-depleted water; Fertilising solutions; Survival index