Glycerol and bioglycerol conversion in supercritical water for hydrogen production.

Catalytic transesterification of vegetable oils leads to biodiesel and an alkaline feed (bioglycerol and organic residues, such as esters, alcohols. . .). The conversion ofbioglycerol into valuable organic molecules represents a sustainable industrial process leading to the valorization of a renewable organic resource. The physicochemical properties in the supercritical domain (T > 374 degrees C, P > 22.1 MPa) transform water into a solvent for organics and a reactant favouring radical reactions. In this context, the conversion ofbioglycerol in supercritical water (SCW) into platform molecules and/or high energetic gases (hydrogen, hydrocarbons) could represent an interesting valorization process. The reported research results concern the conversion of bioglycerol compared to pure glycerol. The experiments have been done in batch autoclaves (5 ml and 500 ml stirred). Solutions of pure (5 or 10 wt%) and crude (3.5 wt%) glycerol have been processed with or without catalyst (K2CO3 1.5 wt%) in the range of 450-600 degrees C. The molecular formula of bioglycerol was determined as C4.3H9.7O1.8Na0.1Si0.08. Glycerol was partially decomposed in the batch systems during the heating (42% before reaching 420 degrees C) and some intermediates (propanediol, ethylene glycol . . .) were quantified, leading to a proposition of a reaction pathway. Acrolein, a valuable platform molecule, was mainly produced in the absence of catalyst. No solid phase was recovered after SCW conversion of pure and bioglycerol in batch reactors. The optimal parameters for gasification were 600 degrees C, 25 MPa for bioglycerol and 525 degrees C, 25 MPa, for pure glycerol. In these operating conditions, 1 kg of pure or bioglycerol leads to 15 and, respectively, 10 mol of hydrogen. Supercritical water gasification of crude glycerol favoured the generation of light hydrocarbons, while pure glycerol promoted H2 production. SCW conversion of glycerol (pure and crude) allows to obtain simultaneously energetic gases (respectively 2600 and 4000 kcal/kg glycerol) and valuable platform molecules.

Pollutants leaching behaviour from solidified wastes: a selection of adapted various models.

Leaching tests are essential in the environmental assessment of stabilized wastes. Research programmes were conducted on their interpretation in order to develop tools for the evaluation of long term release of pollutants contained in solidified wastes. Models for the leaching of porous materials are discussed in this paper according to the specificity of the chemical species (i.e. transport model with total dissolution of species-diffusional model; transport model with progressive dissolution of species due to limitation of solubility-shrinking core model; and the model coupling transport and chemical phenomena). The leaching behaviour of pollutants (i.e. lead) solidified in a cement matrix was studied under different chemical conditions. Results have shown that the release of species whose solubilities depend on the physico-chemical conditions, and especially the pH (e.g. amphoteric metals), is governed by the solubility of the species in the pore water at local conditions and by the pH evolution within the matrix. A coupled dissolution/diffusion model was developed to describe the release of chemically complex species contained in a porous medium in contact with water. Leaching tests of cement matrices and artificial porous matrices containing calcium hydroxide and pollutants were conducted in order to validate the coupled dissolution/diffusion model. A good assessment of the retention of some pollutants contained in cement matrices could then be obtained by the association of two tests: solubilization of the pollutants related to the chemical context (pH) under steady state conditions and monolithic long term dynamic leaching tests in order to characterize the evolution of the chemical context (pH) and consequently the release of pollutants. The objective is to integrate this approach in the standardization process (CEN TC 292- WG 6, in progress).

Leaching assessment of road materials containing primary lead and zinc slags.

Characterisation of the leaching behaviour of waste-containing materials is a crucial step in the environmental assessment for reuse scenarios. In our research we applied the multi-step European methodology ENV 12-920 to the leaching assessment of road materials containing metallurgical slag. A Zn slag from an imperial smelting furnace (ISF) and a Pb slag from a lead blast furnace (LBF) are investigated. The two slags contain up to 11.2 wt% of lead and 3.5 wt% of zinc and were introduced as a partial substitute for sand in two road materials, namely sand-cement and sand-bitumen. At the laboratory scale, a leaching assessment was performed first through batch equilibrium leaching tests. Second, the release rate of the contaminants was evaluated using saturated leaching tests on monolithic material. Third, laboratory tests were conducted on monolithic samples under intermittent wetting conditions. Pilot-scale tests were conducted for field testing of intermittent wetting conditions. The results show that the release of Pb and Zn from the materials in a saturated scenario was controlled by the pH of the leachates. For the intermittent wetting conditions, an additional factor, blocking of the pores by precipitation during the drying phase is proposed. Pilot-scale leaching behaviour only partially matched with the laboratory-scale test results: new mass transfer mechanisms and adapted laboratory leaching tests are discussed.

Leaching of inorganic contaminants from cement-based waste materials as a result of carbonation during intermittent wetting.

Characterization of the leaching behavior of wastes is a crucial step in the environmental assessment for reuse or disposal scenarios. The release of inorganic contaminants from waste materials is typically evaluated by tank leaching of continuously water-saturated material. However, materials, in many field or management scenarios, experience cyclic wetting and drying under varied environmental conditions (i.e. variable relative humidity, atmospheric CO2 or CO2 from biologic activities). During periods of storage in an unsaturated environment, many processes may occur that can influence the release potential and release rate of inorganic constituents. The research presented here was carried out to examine how the phenomena of carbonation during drying influence the release of inorganic contaminants from Portland cement-based materials during cyclic wetting and storage. Batch equilibrium leaching tests were used to determine constituent solubility as a function of pH. Dynamic leaching tests on monolithic material were carried out to determine the rate of constituent release as a function of leaching time and intermittent storage conditions. This paper presents the results observed for three typical waste constituents, arsenic, cadmium and lead.

Modeling of solid/liquid/gas mass transfer for environmental evaluation of cement-based solidified waste.

A physicochemical and transport model has been developed for the long term prediction of environmental leaching behavior of porous materials containing inorganic waste solidified with hydraulic binders and placed in a reuse scenario. The reuse scenario considered in the paper is a storage tank open to the atmosphere including material leaching with water and carbonation through the leachate contact with air. The model includes three levels: (i) the physicochemical pollution source term (chemical equilibria in the pore water and diffusion in the porous system); (ii) chemical equilibria and mass transfer in the tank; and (iii) gas/liquid transfer of carbon dioxide. The model was applied to the case of a material obtained through solidification of Air Pollution Control (APC) residues from Municipal Solid Waste Incinerator (MSWI). The simulation results are in good agreement with two scale experimental data: laboratory and field tests. Experimental data and simulations show the main trends for release of elements contained in the material: (i) the release of alkaline metals and chloride is not significantly influenced by carbonation and (ii) the release of Ca and Pb is governed by chemical equilibria in pore water and diffusion, while their speciation in the leachate is determined by pH and the presence of carbonate ions.

Improved white blood cell functions: additional effects of membrane plasmapheresis.

The changes in cellular functions were analyzed in 4 rheumatoid arthritis and 2 biliary cirrhosis patients. Impaired T-cell functions (low lymphocyte transformation reactivity (LTR) to Con A), seen in one cirrhosis patient before MP, improved with MP. MP also removed inhibitory factor(s) for LTR from the plasma of this patient. RA patients tended to have decreased Con A response and enhanced PWM response. MP enhanced LTR in 2 patients, but lowered LTR in patient who had been taking immunosuppressive drugs. Changes in lymphocyte populations occurred and included a substantial increase of T cells. A primary effect was an increase of helper T-cells. During MP, early leukopenia accompanied by complement activation and secondary leukocytosis were observed. Phagocytic PMNs activated by this process had significant augmentation of their O-2 generating activity as measured by chemiluminescence. This was evident in severe RA and in 2 cirrhosis patients with low phagocytic cell function before MP. This activation of phagocytes by MP may lead to additional beneficial effects by further lowering MMs such as immune complexes from plasma. A better understanding of these phenomena is necessary to assess the overall therapeutic response to MP, especially in patients where cellular mechanisms are important in pathogenesis of their disease.

Incidencia de desnutricion y atencion medica en ninos de bajo peso de nacimiento y peso de nacimiento normal en un consultorio periferico. / Incidence of malnutrition and medical care in infant with low birth weight and normal birth weight in a suburban policlinic

Se estudiaron 46 ninos de bajo peso de nacimiento (peso de nacimiento menor o igual a 2.500 gramos), y 129 ninos de peso de nacimiento normal (peso de nacimiento mayor o igual a 2.501 gramos), controlados en un consultorio periferico de Santiago, con el objetivo de describir la incidencia de desnutricion en ambos grupos y determinar la magnitud de las acciones de salud otorgadas a ambos grupos hasta los seis meses de edad. Se comen tan algunas de las dificultades para catalogar el estado nutricional de los ninos de bajo peso de nacimiento y se destaca la necesidad de elaborar acciones de salud especialmente dirigidas a estos ninos, a nivel de la atencion primaria de salud, como corresponde a su condicion de "alto riesgo"