Developments in the understanding and modeling of the agglomeration of suspended crystals in crystallization from solutions

International audienc

Optimal control of crystallization of alpha-lactose monohydrate

16 pagesInternational audienceWe present a mathematical model for solvated crystallization of alpha -lactose monohydrate in semi-batch mode. The process dynamics are governed by conservation laws including population, molar and energy balance equations. We present and discuss the model and then control the process with the goal to privilege the production of small particles in specific the range. We compare several specific and unspecific cost functions leading to optimal strategies with significantly different effects on product quality. Control inputs are temperature, feed rate, and the choice of an appropriate crystal seed

Ultrasound assisted crystallization of a new cardioactive prototype using ionic liquid as solvent

6th Meeting of the European-Society-of-Sonochemistry (ESS), 15/04/2019 au 19/04/2019, Besancon.International audienceThis work deals with the antisolvent crystallization of LASSBio-294 (3,4-methylenedioxybenzoyl-2-thienylhydrazon) assisted by ultrasound. An ionic liquid (IL), 1-ethyl-3-methylimidazolium methyl phosphonate [emim][CH3O(H)PO2] was used as solvent and water as antisolvent. The influence of the following parameters on crystals properties (size distribution, morphology, residual solvent and in vitro dissolution) were studied with two mixing mode (quick and dropwise) of solution with antisolvent. The impact of washing and drying process was also evaluated. Comparative studies of conventional crystallization conditions (without ultrasound) were also performed. The effect of ultrasound on LASSBio-294 recrystallized properties was influenced by the add mode, water/IL ratio and drug solution concentration. As example, US promoted the formation of small crystals with high residual IL under the following conditions: quick addition, high drug solution concentration and high water/IL ratio. However, despite the decrease of elementary particle size, ultrasound did not avoid crystals agglomeration. The drug dissolution rate was affected by the physical structure of agglomerates. When employed as drying process of washed crystals, spray drying reduced this agglomeration and improved the dissolution of LASSBio-294 crystals

Étude de la précipitation du silicate de magnésium amorphe assistée par ultrasons (synthèse, caractérisation et modélisation)

Le talc naturel est utilisé en tant que charge de haute performance des matrices polymères, car il permet d'améliorer leurs propriétés mécaniques. Pour cela, la dispersion de la charge dans la matrice doit être de qualité, ce qui implique que les particules soient nanométriques. Or, obtenir des particules nanométriques par broyage s'avère coûteux énergétiquement et économiquement. L'étude d'une opération de précipitation a conduit à la synthèse de silicate de magnésium amorphe constitué de particules primaires nanométriques. L'analyse de surface du solide par chromatographie gazeuse inverse a été employée afin de prédire les interactions entre le solide et la matrice polymère. La constante d'équilibre du solide amorphe et les vitesses de cristallisation ont pu être identifiées après modélisation des équilibres chimiques.Natural talc is used as an high performance filler in polymer matrices because it enables to improve mechanical properties. In order to improve these properties, a good-quality dispersion of the filler in the polymer matrix is necessary, that involves particles being nano-sized. However, getting nano-sized particles by milling processes is expensive and very energetic. The study of a precipitation operation has led to the synthesis of amorphous magnesium silicate whose primary particles are nano-sized. Solid surface analysis by inverse gas chromatography has been made in order to predict interactions between solid and polymer matrix. Equilibrium constant of amorphous solid and crystallization rates have been identified after modelling of chemical equilibria.TOULOUSE-INP (315552154) / SudocSudocFranceF

Crystallization of α-glycine by anti-solvent assisted by ultrasound

International audienc

Mechanism of hydrochar formation from black liquor

Hydrothermal carbonization is gaining increasing attention, since hydrochar demonstrates benefits for a large range of applications (biofuel, energy storage, electrodes…) [1]. The generation of solid is basically performed from solid materials (biomass or waste) making difficult the understanding of the phenomena involved. The aim of this study is to better understand the generation of hydrochar in subcritical conditions using black liquor. Black liquor (BL) is an alkaline liquid residue of paper industry containing high concentration of dissolved organics (lignin, partially hydrolyzed cellulose), and a high inorganics content (K, Na, Ca, S…). that makes it a high-value biomass. BL was chosen for its high water, organic and inorganic contents of respectively 80, 14 and 6 wt%. The study has been performed in batch reactor at 350°C, under autogenous pressure for various reaction times (0.5 to 24h). Please click Additional Files below to see the full abstract

High bubble concentrations produced by ultrasounds in binary mixtures

7th Meeting of the European‐Society‐of‐Sonochemistry, BIARRITZ GUETHARY, FRANCE, MAY 14‐18, 2000International audienceIt was discovered that simultaneous insonification and air blowing of different aqueous binary solutions such as water/sodium‐dodecyl‐sulphate (SDS), water/methanol or water/potassium‐sulphate yields a very concentrated bubble cloud invading the whole vessel in a few seconds. After the end of insonification, this cloudiness remained in the solution for about 1 min. The phenomenon was investigated by computer‐treatment of solution pictures recorded every second after the end of insonification. Turbidity appeared to increase with ultrasound power, and also with SDS concentration. During the disappearance of the cloud, a turbidity front appeared rising and spreading upward. This front was studied in the characteristic plane and interpreted as a spatial segregation of different bubble sizes rising with different terminal velocities. The bubble sizes involved were estimated to about 10 mum. Adsorption of surface active species are invoked to explain the cloud formation and its abnormally slow disappearance, but the occurrence of the phenomenon for potassium‐sulphate salt remains unexplained

Contrôle de la cristallisation du alpha-lactose monohydraté

National audienceLa cristallisation est une opération utilisée dans différents domaines industriels comme la pharmacie, l'agro-alimentaire ou la chimie fine. Ce processus consiste à isoler un produit en solution pour le récupérer sous forme solide dans l'objectif de conférer au solide synthétisé des spécifications voulues en vue de contrôler ses propriétés d'usage. Un grand intérêt est porté à l'étude du processus de cristallisation afin de le maîtriser, et donc d'améliorer les propriétés du produit final. Un modèle dynamique fiable décrivant les phénomènes mis en jeu est nécessaire pour l'étudier, et appliquer des stratégies de contrôle afin de produire des solides conformes aux cahiers des charges et aux exigences industrielles. Dans ce travail, nous nous intéressons à la cristallisation du α-lactose monohydraté en mode semi-continu avec ensemencement. Le lactose est un sucre réducteur présent dans le lait, qui existe sous deux formes anomériques α et β en solution (mutarotation). La modélisation mathématique de la cristallisation du α-lactose monohydraté comprend le bilan de population sur les cristaux de α-lactose monohydraté, les bilans de matières sur le α-lactose, le β-lactose et l'eau, avec prise en compte de la mutarotation et le bilan d'énergie. Cette étude présente le contrôle du processus de cristallisation selon deux objectifs d'optimisation : minimisation du taux de nucléation et minimisation du coefficient de variation de la distribution de taille en volume

Inverse gas chromatography a tool to follow physicochemical modifications of pharmaceutical solids: Crystal habit and particles size surface effects

Powders are complex systems and so pharmaceutical solids are not the exception. Nowadays, pharmaceutical ingredients must comply with well-defined draconian specifications imposing narrow particle size range, control on the mean particle size, crystalline structure, crystal habits aspect and surface properties of powders, among others. The different facets, physical forms, defects and/or impurities of the solid will alter its interaction properties. A powerful way of studying surface properties is based on the adsorption of an organic or water vapor on a powder. Inverse gas chromatography (IGC) appears as a useful method to characterize the surface properties of divided solids. The aim of this work is to study the sensitivity of IGC, in Henry’s domain, in order to detect the impact of size and morphology in surface energy of two crystalline forms of an excipient, d-mannitol. Surface energy analyses using IGC have shown that the α form is the most energetically active form. To study size and shape influence on polymorphism, pure α and β mannitol samples were cryomilled (CM) and/or spray dried (SD). All forms showed an increase of the surface energy after treatment, with a higher influence for β samples (γsd of 40–62mJm−2) than for α mannitol samples (γsd of 75–86mJm−2). Surface heterogeneity analysis in Henry’s domain showed a more heterogeneous β-CM sample (62–52mJm−2). Moreover, despite its spherical shape and quite homogeneous size distribution, β-SD mannitol samples showed a slightly heterogeneous surface (57–52mJm−2) also higher than the recrystallized β pure sample (∼40mJm−2)