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The aim of this study was to investigate the use of Fenton’s reagent for the degradation of polycyclic aromatic hydrocarbons (PAHs) in sewage sludges. As Fenton’s reagent generates hydroxyl radicals that further oxidise pollutants in the solution, our efforts focused on finding experimental conditions that would ensure the stability of aqueous PAH solutions. The use of Teflon recipients along with the addition of a co-solvent were required to limit adsorption effects. A non ionic surfactant (Brij-35) was found to be a more suitable co-solvent instead of using an organic solvent as it minimises hydroxyl radical consumption. However it was not efficient in desorbing PAHs contained in sludge samples after 24 h contact time, even at concentrations above its critical micellar concentration.

The adsorption-desorption mechanisms at the interface between organic and inorganic soil colloids influence the movement of pesticides, and in turn their bioavailability. Here we demonstrate the potential of high resolution magic angle spinning nuclear magnetic resonance (H HR-MAS) to assess insitu interactions of pesticides at the solid aqueous interface. We used layered double hydroxides (LDH) also called anionic clays, due to their environmental relevance as soil models and cleaner materials for decontamination processes. We studied the adsorption behaviour of the pesticide 4-chloro-2-methylphenoxyacetic acid (MCPA) on anionic MgAl-clays. Our findings demonstrate that the mobile and immobile fractions of the pesticide can be unambiguously distinguished by H high resolution magical angle spinning nuclear magnetic resonance (H-HR-MAS-NMR).

The photo- and biodegradation of atrazine in the presence of several soil constituents, in particular earthworm casts collected from agricultural soils, were investigated. Earthworm casts were found to favour the photodegradation of atrazine but did not affect its biodegradation, as well as commercially available humic acids. The organic matter content of casts, even rather poor, increased the photodegradation rate. In contrast, the lack of effect of earthworm casts on the biodegradability may be due to the absence of minerals with swelling layers.

Following evidence for the intoxication of bees, the systemic insecticide imidacloprid was suspected from the mid nineties of having harmful effects. Recently, some studies have demonstrated that imidacloprid is toxic for the bees at sub-lethal doses. These doses are evaluated in the range between 1 and 20 µg kg, or less. It appeared thus necessary to study the fate of imidacloprid in the environment at such low levels. Thus, we developed methods for the determination of low amounts, in the µg kg range, of the insecticide imidacloprid in soils, plants and pollens using high pressure liquid chromatography — tandem mass spectrometry (LC/APCI/MS/MS). The extraction and separation methods were performed according to quality assurance criteria, good laboratory practices and the European Community’s criteria applicable to banned substances (directive 96/23 EC). The linear concentration range of application was 1–50 µg kg of imidacloprid, with a relative standard deviation of 2.9% at 1 µg kg. The limit of detection and quantification are respectively LOD = 0.1 µg kg and LOQ = 1 µg kg and are suited to the sub-lethal dose range. This technique allows the unambiguous identification and quantification of imidacloprid. The results show the remanence of the insecticide in soils, its ascent into plants during flowering and its bioavailability in pollens.

We studied the impact of a sulfonylurea-based herbicide on the growth of aquatic microbes including photosynthetic and non-photosynthetic protozoa, and ex-symbiotic and non-symbiotic free living algae. This herbicide is designed to block the biosynthesis of branched amino acids in plants. A commercial sulfonylurea-based herbicide containing methyl 3-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)carbamoyl]-sulfamoyl]-2-thiophenecarboxylate was added to the culture of (green paramecia), and , an ex-symbiotic algae isolated from green paramecia and free-living , at various concentrations ranging from 0.01 to 1 000 mg l. The viability of protozoa and algae was examined under microscopy, 1 week after addition of the herbicide. High concentrations of herbicide (100–300 mg l) were shown to be inhibitory to the growth of symbiotic algae and free living . The same range of herbicide concentrations was shown to be at lethal level for green paramecia and other non-photosynthetic paramecia. The herbicide showed no lethal effect in . Instead, the growth in was markedly enhanced. In addition, treatment with the herbicide resulted in marked changes in size and shape of the cells seriously affecting the euglenoid movement. Lastly we conclude that the sulfonylureic herbicides may not be harmless to aqueous environment.

The photochemical behaviour of the sulfonylurea herbicide rimsulfuron, -[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyridinesulfon amide, on silica and clay minerals, used as soil surrogates, was investigated and compared to a natural soil sample. The antagonistic behaviour of adsorption process and chemical degradation with respect to photodegradation was assessed and the formation of photoproducts was also determined. Results showed that all chemical and photochemical processes responsible for the disappearance of the herbicide follow a second order kinetic. The photochemical degradation of rimsulfuron was strongly affected by retention phenomena: with increasing of the adsorption capability of supports the photoreactivity of the herbicide decreased. The extraction rate of the herbicide covered the following values: soil 59.5%, illite 48.5%, aerosil 22.2%, montmorillonite 21.0%, showing that silica and clay minerals can retain and protect rimsulfuron from photodegradation much more than soil. Though, adsorption of the herbicide was always accomplished to a chemical reactivity of solid substrates. -[(3-ethylsulfonyl)-2-pyridinyl]-4,6-dimethoxy-2-pyridineamine and -(4,6-dimethoxy-2-pyrimidinyl)--[(3-(ethylsulfonyl)-2-pyridinyl)]urea were found both as photochemical and chemical metabolites.

The interactions of the two phenolic endocrine disrupters nonylphenol and bisphenol A and of two herbicide metabolites (hydroxydesethyl terbuthylazine and desethyl terbuthylazine) with dissolved humic and fulvic acids were investigated by means of dialysis, using C-labeled compounds. Experiments were carried out at different pH values. The strength of xenobiotic-organic matter interactions was quantified by calculating organic carbon-normalised distribution coefficients . The results show that pH changes in the range of 3 to 10 had little or no impact on the association of both phenols and desethyl terbuthylazine to humic acids. In contrast, the values for hydroxy-desethyl terbuthylazine association to humic acids at pH 3 and 4.5 were nearly one order of magnitude higher than those at neutral and basic pH. Association of the xenobiotics to fulvic acids was only observed at low pH and about one order of magnitude weaker than to humic acids under identical conditions. We conclude that the binding of the investigated xenobiotics occurs mainly via hydrophobic interactions. Results from additional soil sorption experiments indicated similar binding mechanisms to soil organic matter and dissolved humic acids for nonylphenol and bisphenol A. Due to strong interactions between dissolved humic acids and soil, the xenobioticorganic matter interactions did not affect the sorption of the investigated compounds to soil.

Volunteer "amateur" gardeners were observed, but not supervised, while they mixed, then applied carbendazim, and decontaminated their equipment. A whole body dosimetry method was used, including dosimeters on hands, feet and face. Personal air samplers collected airborne pesticide in the breathing zone. Analysis of the tank mixes prepared by volunteers indicated that the final concentration ranged from 55 to 177% of the intended concentration. Areas of body most heavily contaminated during mixing were the hands, with levels of up to 25 mg of active substance (a.s.) found due to spillages during measurement. Residues of pesticide within the measuring cap were up to 31 mg of a.s. During application the arms, hands, front torso and feet were most contaminated. Typical contamination rates during application were 20 ml h of the diluted tank mix: up to 10 mg h of active substance, with typical applications in these scenarios lasting 5 to 15 min.

Carbon dioxide is a renewable resource of carbon when we consider the reuse of existing CO as a carbon source for producing chemicals. The development of new applications is of major interest from the point of view of carbon dioxide sequestration and within the scope of green chemistry. For example, using CO instead of CO or COCl for chemical synthesis constitutes an attractive alternative avoiding hazardous and toxic reactants. However, it has the lowest chemical reactivity, which is a serious drawback for its transformation. Supercritical CO as a reaction medium offers the opportunity to replace conventional organic solvents. Its benign nature, easy handling and availability, non volatile emitting, and the relatively low critical point ( = 73.8 bar, = 31 °C) are particularly interesting for catalytic applications in chemical synthesis, over a wide range of temperatures and pressures. The benefits of coupling catalysis and supercritical fluids are both environmental and commercial: less waste and less emission of volative organic compounds (VOCs), improved separation and recycling, and enhanced productivity and selectivity.

The case study described in this paper concerns the reaction of carbon dioxide with alcohols to afford dialkyl carbonates with special emphasis on dimethyl carbonate. It is of significant interest because the industrial production of this class of compounds, including polycarbonates, carbamates, and polyurethanes, involves phosgene with strong concerns on environmental impact, transport, safety and waste elimination. The future of carbon dioxide in green chemistry, including supercritical applications, is highly linked to the development of basic knowledge, know-how, and tools for the design of catalyst precursors and reactors.

Mechanical energy was first used for running chemical reactions three centuries before Christ, for the preparation of mercury. The term mechanochemistry was introduced by Ostwald in 1893. The scientific principles of the technology were discussed by Heinicke in 1984. In this technology, energy transfer takes place through high energy milling of solids that undergo several transformations. Chemical reactions can also take place, that avoids the use of solvents with great benefit from the environmental point of view. As a matter of fact, mechanochemistry has been used so far for the preparation of new materials and running chemical reactions in absence of solvents. More recently, it has been used within the new perspective of application to solving environmental problems. In this paper, the utilization of mechanochemistry as a solid state technology for the dehalogenation of polychlorobiphenyls (PCBs) present in contaminated soil is described. The abatement of PCBs is quantitative. The high energy milling of soil with ternary hydrides represents a valid alternative to the technology based on the use of metal sodium and water, due to the higher safety, and more controlled reaction conditions.