Behaviour of mesogenic side group polyacrylates in dilute and semidilute regime

The solution behaviour of a new mesogenic side group polyacrylate in tetrahydrofuran and toluene has been investigated by static and dynamic light scattering. In the dilute regime the polymer behaves as typical polydisperse linear chains in good solvent and the dynamics is dominated by a single fast mode. Cluster formation was detected starting at a concentration around 50 g l⁻¹. It seems to be independent of the solvent as well as of polymer molecular weight. In the semidilute regime, the behaviour of the reduced osmotic modulus leads to the conclusion that repulsion between the chains is stronger than in linear macromolecules. The appearance of larger clusters was revealed above a characteristic concentration and is slightly dependent on the polyacrylate molecular weight. The dynamics was generally characterised by a fast mode related to the cooperative diffusion and by a slow mode associated with large clusters. The existence of a network of multiconnected clusters is envisaged with increasing solution concentration.     

Oleic acid esterification with ethanol under continuous water removal conditions

The production of ethyl ester was investigated using a new reaction system consisting of a reactor coupled to an adsorption column. The adsorption system was used to shift the equilibrium toward ethyl ester production by removing the water from commercial ethanol and the water produced during the esterification reaction. A condenser placed above the adsorption column was responsible to condensate the vapor, returning water free ethanol to the reactor. Ethyl ester was produced by esterification of oleic acid and ethanol using sulfuric acid as catalyst. The results showed a yield of 99.9%. The best operating condition was found operating the reactor at 110 °C, 1% of catalyst (w/w) and with an oleic acid to ethanol ratio of 1:3.     

A New Simplified and Stability Indicating Liquid Chromatography Method for Routine Analysis of Isoflavones Aglycones in Different Complex Matrices

In this work, a stability indicating method for routine analysis of isoflavones in different matrices was developed and validated. In order to simplify the analytical method, the glycosides were previously hydrolyzed to the corresponding aglycone forms. The separation of all isoflavone aglycones was achieved in 23 min, with a total time of analysis of 30 min, using trifluoroacetic acid 0.1 % (v/v) and acetonitrile:trifluoroacetic acid (100:0.01, v/v) as mobile phase. The LC method specificity was evaluated by the analysis of isoflavone standards submitted to acidic, alkali, neutral, oxidative, and photolytic stress conditions. The isoflavones degraded in alkali at 60 °C or in alkali under ulraviolet C (UVC) radiation, forming, in both conditions, three degradation products D1, D2, and D3 which were analyzed by liquid chromatography mass spectroscopy (LC-MS/MS). The method showed linearity higher than 0.999 with the concentration ranged from 0.1 to 10 μg ml^-1 for all isoflavone aglycones. The limits of quantitation obtained using calibration curves were from 0.28 to 0.37 μg ml^-1 and the intermediary precision at three levels (2, 6, and 10 μg ml^-1) showed RSD values between 0.03 and 0.25 %. After the performed validation, the LC method was applied to compare the isoflavone aglycones content in three different matrices: Glycine max beans, Glycine max dry extract, and isoflavone aglycone loaded nanoemulsion. The repeatability data showed RSD values between 0.02 and 1.41 % and the intermediary precision at three levels showed RSD values between 0.05 and 1.99 %. The recovery data of the isoflavone aglycones standards in the matrices at three levels were between 90.74 and 106.43 %.     

Spent grape pomace as a still potential by‐product

This research consisted of the determination of several phenolic compound and fatty acid contents of the grape seeds and skins obtained from pomace PRE and POST distillation. The quantification of flavan‐3‐ol composition, the determination of the mean degree of polymerisation (mDP) of the condensed tannins and the estimation of their antiradical activity have been also realised. The distillation process applied did not seem to significantly affect the fatty acid distribution of extracted oils. Conversely, the antiradical activity of both seeds and skins changed. Heating significantly decreased the seeds’ activity, while increased the skins’ activity to around 50% compared to PRE sample. The conclusion from this study is that despite the degradation caused by the drastic conditions, many interesting, valuable compounds are still present in the extract from the waste of this process, which makes it a useful matter for a better exploitation than as fertiliser or for producing renewable energy.     

Biodiesel production from waste coconut oil by esterification with ethanol: The effect of water removal by adsorption

The production of biodiesel by esterification with ethanol using waste oil generated in the refining of coconut oil was investigated in this study. The reaction was performed with and without adsorption of water in order to verify the effect of removing water on the reaction conversion. Methanol was also evaluated as an esterification agent. For both ethanol and methanol, conversions over 99% mol were observed. Simultaneous water adsorption allowed the use of lower alcohol/oil molar ratios thus enabling better economics to a possible industrial process.