Catálogo de publicaciones - libros

Novel biofilm reactor systems, a parallel trickling biofilter (TBF) system and a two-stage continuous stirred tank reactor (CSTR)/trickling biofilter system, were developed and operated for long-term continuous treatment of gas-phase trichloroethylene (TCE) by the bacterium G4. The effects of trichloroethylene concentrations on reactor performances were analyzed. The critical trichloroethylene elimination capacities were determined to be 8.6 and 25.3 mg trichloroethylene l d, respectively.

The cyclic glucose oligosaccharides known as cyclodextrins (CDs) are able to form host-guest inclusion complexes with a variety of organic compounds including a number of pollutants. Substituted cyclodextrins in which one or more hydroxyl groups have been modified with, e.g. -CH, -CHCH(OH)CH, -CHCOO, -COO and -SO, have many desirable properties compared with unmodified cyclodextrins, including greater aqueous solubility and binding ability. As part of studies on the abiotic degradation and soil-water interactions of pesticides and other hydrophobic organic compounds, in this work we have examined a number of substituted -cyclodextrins for use as complexing agents for the enhancement of aqueous solubility of the organic pollutants trichloroethylene (TCE) and perchloroethylene (PCE). Solubility enhancement factors ( / ) up to 5.5 and 14 were determined for trichloroethyelene and perchloroethyelene respectively. Binding constants for trichloroehylene with the substituted cyclodextrins, evaluated using H nuclear magnetic resonance (NMR), ranged from 3 M to 120 M. In experiments with soil-derived peat contaminated by perchloroethylene and trichloroethylene, it was shown that selected cyclodextrins are capable of effective removal of the contaminants, suggesting that a suitably substituted -cyclodextrin may be a valuable additive in pump-and-treat protocols for site remediation of poly-chlorinated organics.

Over the years, chemists have been known to make a significant contribution to science, and to generate new chemical substances as a result of their professional activities. Over 20 million compounds have been recorded in the literature, however, because of their use in chemical processes and their disposal in waste products, only a smaller number of these compounds are available for furture use. Therefore, there is a tremendous loss of molecular diversity and chemical heritage. Reproduction of samples, if successful, is expensive and time-consuming. It may also contribute to a substantial damage to the environment. Chemical sample archives are priceless resources that can tremendously facilitate and speed-up discovery of new drugs, and new compounds, as well as the development of many other chemical products, with industrial, pharmaceutical, agricultural, educational, and research applications. The Molecular Diversity Preservation International (MDPI) project has been successful in carrying out worldwide collections/deposits, exchanges, and "recycling" of a significant number of chemical samples.

Materials prepared by sol-gel method combined with drying under supercritical conditions are called aerogels. Titania aerogels appear to be promising photocatalysts. In this study the aerogels were synthesized from tetraisopropyl orthotitanate (IZPT) diluted in anhydrous methanol or isopropanol. The properties of titania aerogels were changed by applying various preparation ways. The adsorption capability of the aerogels (kinetics and isotherms of adsorption) was checked. They revealed a multistep adsorption, characteristic for mesoporous solids. The physicochemical properties of the catalysts were determined using X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The photocatalytic tests of the aerogels were conducted using aqueous solutions of 4-hydroxy-benzoic acid and -chlorophenol. The results prove that photocatalytic properties of the aerogels strictly depend on adsorption capacity.

A new process for the detoxification of phenol-containing waste waters based on catalytic hydrogenation suitable for a wide range of compounds is proposed. After an introduction pointing out the advantages of this approach, the principle of the multifunctional process is presented. Then two examples of application of this process for the treatment of polluted waste waters are reported; one containing chlorophenols and the other containing mixture of phenols of olive oil waste water. Using 4-chlorophenol as a model molecule of monoaromatic chlorophenols and tyrosol of phenols encountered in olive oil waste waters, the kinetics of catalytic hydrogenation was studied. In both cases, a scheme of the reaction was elucidated, different kinetics models were established and a dynamic simulation software was used for helping in their discrimination and for parameter estimation. In both cases, total conversion was achieved. The global rate of 4-chlorophenol conversion into cyclohexanol at 0.4 MPa and 353 K was 3.43 g hg while the rate of tyrosol conversion at 1 MPa and 353 K was 1.42 g hg.

The increasing use of aprotic solvents in the industry leads to the set up of new wastewater treatment technologies adapted to the specificity of these compounds. The case of dimethyl sulfoxide (DMSO) is particularly interesting due to the specific properties of this component. Depending on concentration and the presence of other compounds in the effluent, several technologies can be chosen: concentration with reverse osmosis, biodegradation with specific process to avoid dimethyl sulfide (DMS) odours, oxidation in dimethyl sulfone (DMSO) by various oxidants. The choice has to be made according to economical and technical considerations. In this paper, different options are detailed with advantages and drawbacks.

This work discusses the use of rice hull ash as raw material to prepare cements, similar to Portland cement. Rice hull is an agricultural by-product containing about 20% of silica. Usually, this material is burned at the rice fields generating small silica particles, which may cause respiratory and environmental damage. We describe here the use of rice hull ash as a raw material to prepare -CaSiO, which is a component of commercial Portland cement. Heating rice hull at 600 °C gave silica with a surface area of 21 mg. Rice hull ash was mixed with CaO and BaCl · 2HO in several proportions, added stoichiometricaly in order to keep a ratio (Ca + Ba) / Si = 2 or 1.95. The solids were mixed with water 1/20 (w/w) and sonicated for 60 min. The suspensions were dried, grounded and heated. Cements with structure similar to that of -CaSiO were obtained at temperatures as low as 700 °C.

Many reports suggest the involvement of reactive oxygen species (ROS) in salt stress in plants. To date, it has not been well documented how rapidly plant cells respond to the salt stress by producing reactive oxygen species. Under salt stress, plants are exposed to both the hyperosmotic shock and cation shock. Recently we have shown that treatment with metal cations such as Li,Na,K,Ca,Mg,La,Gd and Al induces burst of O production in tobacco cells; whereas hyperosmotic treatments do not induce O production. Therefore, the salt-induced damages to plant cells mediated by reactive oxygen species may be due to cation shock. This chapter reviews the recent achievements in our understanding of plant response to salt stress. Lastly, we discuss the use of transition metal ions in mitigation of salt-induced reactive oxygen species.

The bioassay LUX-FLUORO test was developed for the rapid detection and quantification of environmental pollutants with genotoxic and/or cytotoxic effects. This bacterial test system uses two different reporter genes whose gene products and their reactions, respectively, can be measured easily and simultaneously by optical methods. Genotoxicity is measured by the increase of bioluminescence in genetically modified bacteria which carry a plasmid with a complete operon for the enzyme luciferase from the marine photobacterium under the control of a DNA-damage dependent so-called SOS promoter. If the desoxyribonucleic acid (DNA) in these bacteria is damaged by a genotoxic chemical, the SOS promoter is turned on and the operon is expressed. The newly synthesized luciferase reacts with its substrate thereby producing bioluminescence in a damage-proportional manner. In the second part of the system, genetically modified bacteria carry the gfp gene for the green fluorescent protein from the jellyfish downstream from a constitutively expressed promoter. These bacteria are fluorescent under normal conditions. If their cellular metabolism is disturbed by the action of cytotoxic chemicals the fluorescence decreases in a dose-proportional manner. The combined LUX-FLUORO test can be used for the biological assessment of the geno- and cytotoxicity of a wide variety of organic and inorganic chemicals including complex mixtures in different matrices.

Freshwater eutrophisation causes blooms of cyanobacteria, including species that produce toxins harmful to animals. We present here a study of the effects of two hepatotoxins: microcystin-LR (heptapeptide) and cylindrospermopsin (alkaloid), on , a photosynthetic protist. Microcystin- LR (0.01–10 εg ml) and cylindrospermopsin (0.13–12.5 εg ml) showed no toxic effect on growth but significantly increased cell productivity. O consumption was significantly stimulated half an hour after the toxin was added for microcystin and 48 h after for cylindrospermopsin for all the concentrations tested. In addition, a drastic inhibition of greening and photosynthesis as well as an 80% increase of reduced glutathione were observed at the high concentrations of cylindrosper-mopsin. Two-dimensional electrophoresis after S amino acid labeling showed that with cylindrospermopsin a 23-kDa protein was induced in the first 2 h, whereas a 29-kDa protein was overexpressed with microcystin and cylindrospermopsin.