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In this work we report a new way of producing wrinkled soft Janus spheres by using scCO 2 . The wrinkles appear in one of the half-hemispheres by the asymmetric UV irradiation of the particles followed by an anisotropic scCO 2 swelling. This treatment allows the fabrication of banded as well as sinusoidal packed wrinkles in the irradiated spheres surface. The particles were prepared from an elastomeric network consisting of two soft segments, polypropylene oxide and polybutadiene. The spheres to be treated by scCO 2 were selected taking into account the chemical composition as well as the elastic and wettability characteristics of the materials.

The fractionation of red wine grape pomace (RWGP) by subcritical water (SBW) extraction/hydrolysis was studied in a semi-continuous reactor. Different temperature programs were used, comprising ramps and plateaus at different temperatures, with different time lengths. Pressure was kept constant at 100 bar. A program applied to previously defatted RWGP (def-RWGP) featuring plateaus at 50, 100 and 190 °C allowed the recovery of virtually all of the hemicellulose, while leaving in the residue essentially all of the lignin and the cellulose. The latter was readily hydrolyzed enzymatically. When using whole RWGP, it was shown that over 85 % of the lipids remained in the residue. The RWGP extracts had contents of phenolic compounds up to 29 g/100 gextract, and were rich in hemicellulose-derived carbohydrates, mostly in the form of oligomers. The extracts exhibited an antioxidant capacity that compared favorably with that of gallic acid.

In this work the phase behavior of the ternary system ethanol/(±)-menthol/CO2 was studied at the temperatures of 313 and 323 K, in the pressure range 8–10 MPa. Experiments were performed using a high pressure phase equilibrium apparatus with a visual cell. CO2 is more selective toward ethanol, separation factors ranging from 1.6 to 7.6 at the conditions tested. The pTxy data obtained were correlated with the Peng–Robinson equation of state combined with the Mathias–Klotz–Prausnitz mixing rule. The model gave a good fitting to the data, with a total average absolute deviation of 3.7%, and was able to predict the occurrence of a three-phase region observed experimentally at 313 K and 9 MPa.

Enzymatic transesterification is becoming a commercially competitive route to biodiesel. Supercritical CO2 (scCO2) is well established as a solvent for extraction processes. Here we analyze the economy of a scCO2-based, enzymatic process, for the production of biodiesel from waste cooking sunflower oil (WCO). The conversion of WCO to fatty acid ethyl esters (FAEE) catalyzed by immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM), and downstream separation to recover biodiesel conforming to the EN14214 norm, were studied in a pilot plant unit. The data generated was used to design an envisaged industrial plant, for which an energy balance was carried out. Investment and production costs were estimated for the conversion of 8000 tonWCO/year. This led to biodiesel costs of 1.64€/L and 0.75€/L (for a WCO price of 0.25€/kg; enzyme prices of 800€/kg and 8€/kg, respectively), which already reflect the ca. 10% impact of glycerol sales.

A continuous process for biodiesel production in supercritical carbon dioxide was implemented. In the transesterification of virgin sunflower oil with methanol, Lipozyme TL IM led to fatty acid methyl esters yields (FAME) that exceeded 98% at 20 MPa and 40 °C, for a residence time of 20 s and an oil to methanol molar ratio of 1:24. Even for moderate reaction conversions, a fractionation stage based on two separators afforded FAME with >96% purity. Lipozyme TL IM was less efficient with waste cooking sunflower oil. In this case, a combination of Lipozyme TL IM and Novozym 435 afforded FAME yields nearing 99%.

The continuous kinetic resolution of (R, S)-1-phenylethanol via enzymatic transesterification was chosen as a benchmark reaction for the study of a complete reaction/separation process using supercritical carbon dioxide. Phase equilibrium data for binary and ternary systems was acquired as a starting point to determine the best conditions of operation. Total conversion of the (R)-isomer of the alcohol was achieved using a 10% molar excess of vinyl laurate. Three separators operating at given temperatures and pressures allowed the recovery of (S)-1-phenylethanol with a purity of 86%. The phase equilibrium data obtained indicates that an additional separation step should allow the recovery of both (S)-1-phenylethanol and (R)-1-phenylethylaurate with over 95% purity. Due to the low solubilities of the target compounds, CO2 from the outlet gas stream of the last separator must be recycled to ensure the technical viability of the integrated reaction/separation of (R, S)-1-phenylethanol.

We performed a comparative study on the activity of Fusarium solani pisi cutinase immobilized on zeolites NaA and NaY, in n-hexane, acetonitrile, supercritical ethane (sc-ethane) and sc-CO2, at two different water activity (aW) values set by salt hydrate pairs in situ and at acid–base conditions fixed with solid-state buffers of aqueous pKa between 4.3 and 10.6. The reaction studied was the transesterification of vinyl butyrate by (R,S)-2-phenyl-1-propanol. The transesterification activity of cutinase was highest and similar in sc-ethane and in n-hexane,about one order of magnitude lower in acetonitrile and even lower in sc-CO2. Activity coefficients (γ) generated for the two substrates indicated that they were better solvated in acetonitrile and thus less available for binding at the active site than in the other three solvents. γ data also suggested higher reaction rates in sc-ethane than in n-hexane, as observed, and provided evidence for a direct negative effect of sc-CO2 on enzyme activity. Manipulation of the acid–base conditions of the media did not afford any improvement of the initial rates of transesterification relative to the blanks (no added acid–base buffer, only salt hydrate pair), except in the case of cutinase immobilized on zeolite NaA in sc-ethane at aW = 0.7. The poor performance of the blank in this case and the great improvement observed in the presence of a basic buffer suggest a deleterious acidic effect in the medium which, an experiment without additives confirmed, was not due to the known acidic character of the salt hydrate pair used to set aW = 0.7. In acetonitrile, increasing aW was accompanied by a decrease in initial rates of transesterification, unlike in the other solvents. There was considerable hydrolysis in acetonitrile, where initial rates of hydrolysis increased about 20-fold from aW = 0.2 to 0.7. Hydrolysis was less pronounced in sc-ethane and in n-hexane, and only at aW = 0.7, and in sc-CO2 butyric acid was detected only at very long reaction times, in agreement with a generally low catalytic activity. Cutinase enantio-selectivity towards the alcohol substrate was low and unaffected by any manipulation of medium conditions. This work has been supported by Fundação para a Ciência e Tecnologia (FCT, Portugal) through the contracts PRAXIS/PBIO/14314/1998 and POCTI/35429/QUI/2000 and the grant PRAXIS XXI/BD/21615/99 (S. Garcia), and by FEDER.We thank Ricardo Baptista for help in the production of cutinase.