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Solvent Extraction of Citric Acid with Different Organic Phases

Advances in Chemical Engineering and Science 2017年第3期7卷 304-324页

作者： Estêv&atilde o Magno Rodrigues Araújo Fabrício Eduardo Bortot Coelho Julio Cézar Balarini tania lúcia santos miranda Adriane Salum Chemical Engineering Department Federal University of Minas Gerais (UFMG) Belo Horizonte Brazil

The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine? 336, ExxalTM 13 tridecyl alcohol, and the aliphatic diluent EscaidTM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine? 336, and 10% w/v of ExxalTM 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28°C ± 2°C) was determined, and the equilibrium constant was calculated (36.8 (mol·l-1)-1.5). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions’ pH is lower than the citric acid pKa1. It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol·l-1)-1.5·s-1 and 5.69 × 10-2 s-1, respectively, were calculated. Coefficients of determination (R2) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and si

关键词： Citric Acid Solvent Extraction Alamine 336 TOA Equilibrium Isotherm

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Individual and Combined Effects of the Extractant,Surfactant and Modifier Concentrations on the Droplet Coalescence Time of the Primary Emulsion in the liquid Surfactant Membrane Extraction Process

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Advances in Chemical Engineering and Science 2018年第4期8卷 205-214页

作者： Adriane Salum lorena da Costa Nascimento tania lúcia santos miranda leandro Dornellas Sampaio Andrade Cibele Konzen Julio Cézar Balarini Estevao Magno Rodrigues Araújo Fabrício Eduardo Bortot Coelho Department of Chemical Engineering Federal University of Minas GeraisBelo HoriozonteBrazil

In this work, the individual and combined effects of the extractant, surfactant and modifier concentrations on the droplet coalescence time of the primary emulsion in the liquid surfactant membrane extraction process were evaluated, through emulsification experiments. Adogen 464 was used as extractant (carrier), and Escaid 110, as diluent. Two systems were studied. The first one composed by the extractant, the surfactant and the diluent, and the second one composed by the same reagents, but with the addition of 1-decanol as modifier. It was observed that, when the modifier is not present in the membrane phase, the surfactant not only stabilizes the primary emulsion, but, apparently, it also plays a role similar to that of the alcohol, promoting the solvation of the amine in a low polarity diluent. Furthermore, the extractant, a quaternary amine, helps to stabilize the primary emulsion in systems without a modifier. For membrane phases consisting of 1 or 5% w/w of Adogen 464 and 2% or 5% w/w of ECA 4360, a concentration of 3% w/w of 1-decanol was sufficient to promote the solvation of Adogen 464 in Escaid 110 and to obtain a low droplet coalescence time.

关键词： liquid Surfactant Membranes Emulsification Adogen 464 ECA 4360 1-Decanol Droplet Coalescence Time

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Taxifolin stability: In silico prediction and in vitro degradation with HPlC-UV/UPlCe ESI-MS monitoring

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Journal of Pharmaceutical Analysis 2021年第2期11卷 232-240页

作者： Fernanda Cristina Stenger Moura Carmem lúciados santos Machado Favero Reisdorfer Paula Angelica Garcia Couto Maurizio Ricci Valdir Cechinel-Filho Tiago J.Bonomini louis P.Sandjo tania Mari Belle Bresolin Pharmaceutical Sciences Graduate Program School of Health SciencesCourse of PharmacyUniversidade do Vale do ItajaíItajaíSC88302-202Brazil laboratory of Research and Development of Drugs Pharmaceutical Sciences Graduate ProgramSchool of Health SciencesCourse of PharmacyUniversidade Federal do PampaUruguaianaRS97500-970Brazil Department of Pharmaceutical Science Universita degli Studi di PerugiaPerugiaPG06123Italy Chemistry Department Universidade Federal de Santa CatarinaTrindadeFlorian opolisSC88040-900Brazil

Taxifolin has a plethora of therapeutic activities and is currently isolated from the stem bark of the tree larix gmelinni(Dahurian larch). It is a flavonoid of high commercial interest for its use in supplements or in antioxidant-rich functional foods. However, its poor stability and low bioavailability hinder the use of flavonoid in nutritional or pharmaceutical formulations. In this work, taxifolin isolated from the seeds of Mimusops balata, was evaluated by in silico stability prediction studies and in vitro forced degradation studies(acid and alkaline hydrolysis, oxidation, visible/UV radiation, dry/humid heating) monitored by high performance liquid chromatography with ultraviolet detection(HPlC-UV) and ultrahigh performance liquid chromatography-electrospray ionization-mass spectrometry(UPlC-ESI-MS). The in silico stability prediction studies indicated the most susceptible regions in the molecule to nucleophilic and electrophilic attacks, as well as the sites susceptible to oxidation. The in vitro forced degradation tests were in agreement with the in silico stability prediction, indicating that taxifolin is extremely unstable(class 1) under alkaline hydrolysis. In addition, taxifolin thermal degradation was increased by *** the other hand, with respect to photosensitivity, taxifolin can be classified as class 4(stable).Moreover, the alkaline degradation products were characterized by UPlC-ESI-MS/MS as dimers of taxifolin. These results enabled an understanding of the intrinsic lability of taxifolin, contributing to the development of stability-indicating methods, and of appropriate drug release systems, with the aims of preserving its stability and improving its bioavailability.

关键词： Dihydroquercetin In silico stability prediction Forced degradation

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