Jacques Molinier

Ozonolysis of lignin-improvement of in vitro digestibility of poplar sawdust

Conditions for optimal digestion of poplar sawdust using ozonolysis were investigated in both a fixed bed reactor and a stirred semibatch reactor. The fixed reactor performed better than the batch reactor. Of the parameters studied, (moisture content of the sample, particle size and ozone concentration in the gas flow), the moisture content of the sawdust had the most significant effect on solubilization. Digestibility was estimated by treating the ozonized samples with cellulose from Trichoderma reesei. Ozone treatment increased accessibility of the enzyme to the substrate.

Separation of tartaric and lactic acids by means of solvent extraction

A study of the possibilities for separating tartaric and lactic acids from winery wastewaters was conducted. Some principal extractants were tested. The organic phase containing TBP, dodecane or TOA, 1-decanol, dodecane permits a selective extraction of one of the acids. The distribution coefficients of both acids with solution of tertiary amine, modifier and diluent were determined. The same organic phase was tested to remove tartaric and lactic acids from a mixture. Taking into account the selective extraction, it was concluded that the most appropriate solvent composition corresponds to 15% (v/v) TOA, 15% (v/v) 1-decanol, and 70% (v/v) dodecane. This solvent was applied in a system of countercurrent extraction which permits to separate successfully tartaric from lactic acid.

Recovery of aconitic and lactic acids from simulated aqueous effluents of the sugar-cane industry through liquid-liquid extraction

The recovery of aconitic and lactic acids from dilute aqueous effluents of the sugar-cane industry by a solvent extraction technique has been investigated in order to reduce environmental pollution and in view of the possible uses of pure solutes in the field of foods and pharmaceuticals. Reactive extraction of carboxylic acids with tributylphosphate dissolved in dodecane was examined. Experiments were performed at 25 °C for three extractant concentrations of 50%, 60% and 70% (mass %) in dodecane. The decrease of specific gravity and viscosity of solvent resulting from the presence of an inert diluent was favourable to the phase settling and the mass transfer. The percentage of acids recovered in the organic phase for a volumetric solvent ratio varying from 0.5 to 5.0 was determined. Taking into account the difference between the partition coefficients for the carboxylic acids under consideration, the selectivity of solvent with regard to aconitic acid also was quantified. Moreover, owing to its water-insolubility, its availability and its low cost, tributylphosphate can be considered as a promising extractant for large-scale applications. © 2000 Society of Chemical Industry

Furfural decarbonylation catalyzed by charcoal supported palladium: Part I — Kinetics

Abstract The rate of furfural decarbonylation was investigated in the presence of a charcoal supported palladium catalyst using potassium carbonate as accelerator in the liquid phase between 150 and 160°C. Reaction speed varied with the quantity of catalyst and increased exponentially with temperature. Activation energy under these experimental conditions was 310 kJ/mol. Reaction by-products were mainly of high molecular weight, resulting from various dimerization reactions involving furan and/or 2-methyl furan. These products covered the surface of the catalyst and blocked active sites, resulting in deactivation.

Furfural decarbonylation catalyzed by charcoal supported palladium: Part II — A continuous process

Abstract During continuous furfural decarbonylation, using a carbon supported palladium catalyst, a high catalytic activity (36 000 g of furan per g of palladium) was observed. Furan productivity remained almost constant for 45 h and then decreased gradually to reach a new low level after 90 h. Analysis of residues indicated that by-products are partly responsible for the decrease in furan productivity.

Effect of reaction medium on ozone mass transfer and applications to pulp bleaching

Abstract Over the last few years, ozone has been considered as an effective reagent for the bleaching of chemical pulp and an alternative to conventional chlorinated compounds which induce environmental pollution. The purpose of this work was to investigate the optimal conditions of the ozonation process with the aim of avoiding the breakdown of carbohydrates present in the pulp. In order to limit the depolymerization of cellulose, which involves a decrease in the pulp strength, various organic compounds called “protectors” were added to the reaction medium. The results reported in this paper show the important role of most additives and their influence on the hydrodynamic phenomena taking place in the ozonation process. Indeed, these products improve the mass transfer and, more particularly, the diffusion of ozone in the pulp. Consequently, their presence enhances the performance of the ozonation stage.

Recovery of calcium tartrate and calcium malate in effluents from grape sugar production by electrodialysis

Abstract This paper deals with the recycling of concentrate during the electrodialysis treatment at 60°C of grape must in order to decrease the effluent pollution volume and to increase the concentration of tartaric and malic acid in the recovery of their insoluble salts. The concentrate extracted slightly below the threshold of salts crystallization is cooled (5°C for 48 h) and crystals of potassium salts are recovered. This concentrate is next recycled, extracted and cooled. The final effluent volume is fifteen times lower than that of the initial must. The cold storage of primary and secondary concentrates eliminates, respectively, 80% and 87% of tartaric acid, 15% and 14% of malic acid. When calcium chloride is added to the effluents, the tartaric acid recovery rate can be 60–75%, while that of malic acid is in the range 29–55%. Maximum recoveries can only be achieved when the effluent concentration is raised to 165 g of malic acid per liter.

Dinuclear rhodium complexes immobilized on functionalized diphenylphosphino-(styrene-divinylbenzene) resins giving high selectivities for linear aldehydes in hydroformylation reactions

Abstract A novel rhodium species grafted onto a polymer has been prepared by reacting the functionalized resin (Res-PPh 2 ) with [Rh 2 (μ-S t Bu) 2 (CO) 4 ] to afford [Rh 2 (μ-S t Bu) 2 (CO) 2 (Res-PPh 2 ) 2 ]. This complex catalyses the hydrofomylation of oct-1-ene under mild conditions with 99–100% selectivity in aldehydes and more than 90% selectivity in linear aldehyde. A peculiar inhibiting effect of dihydrogen has been shown.

RECOVERY OF CARBOXYLIC ACIDS FROM AQUEOUS SOLUTIONS BY LIQUID-LIQUID EXTRACTION WITH A TRIISOOCTYLAMINE DILUENT SYSTEM

Tertiary alkylamines in solution with organic diluents are attractive extractants for the recovery of carboxylic acids from dilute aqueous phases. The aim of this study was to investigate the mechanism for extraction of organic acids from water by a long-chain aliphatic tertiary amine. In order to attain this objective, we studied the liquid-liquid equilibria between the triisooctylamine + 1-octanol + n-heptane system as solvent and an aqueous solution of an individual carboxylic acid such as citric, lactic and malic acids. The experiments showed that the partition coefficient for a particular organic acid depends on the kind of solute, notably when the acid concentration in the aqueous phase is low. A mathematical model, where both chemical association and physical distribution are taken into consideration, is proposed. The model suggests that the various complexes obtained between amine and organic acids contribute to the distribution of the solute between the coexisting phases in equilibrium.

Recovery of aconitic acid from simulated aqueous effluents of the sugar-cane industry through liquid-liquid extraction

Abstract The recovery of carboxylic acids from the by-products of sugar-cane treatments by the technique of solvent extraction has been studied, in order to reduce environmental pollution and in view of the possible uses of aconitic acid in the food-processing and chemical industries. The liquid-liquid extraction process can be considered as an alternative to the classical precipitation method for the separation of aconitic acid from dilute aqueous effluents. In this work, the selected solvent was composed of a mixture of an extractant (tributylphosphate) with a diluent (dodecane). The concentration of tributylphosphate in the mixture of extractant and diluent, the composition of the initial aqueous solution and its pH, as well as the mass: solvent ratio were found to influence the equilibrium of distribution of the carboxylic acid between the organic and the aqueous phases. With a solvent composed of a mixture of tributyphosphate (70 vol%) + dodecane (30 vol%) and a mass:solvent ratio of 5, the percentages of aconitic acid extracted by the solvent were higher than 98% (mass%) whatever the composition of the initial aqueous solution. After the extraction step, the regeneration of solvent could be easily obtained by stripping of solute from the organic phase with a basic aqueous solution. This preliminary study showed the possibilities of the method for use in industrial processes.