Powder: Crystallization Outcome

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Crystallization Outcome Antisolvent crystallization is a technique by which a nonsolvent is added to a concentrated solution to induce crystallization the solute. The addition of xylitol solutions to acetone decreased the solubility of the xylitol solute and thus rapidly generated a supersaturation state. The mixing process between the xylitol solvent and acetone antisolvent is likely to bring about an increase in the molar volume of the xylitol solution, and hence the solubility power towards the xylitol decreases, thus allowing the xylitol solute to precipitate. In comparison to other crystallization media, when xylitol was crystallized in the presence of PVA16000, the crystallization medium exhibited a high viscosity (nearly solidified). Thus, additional distilled water was added to allow more xylitol to be dissolved and thus liquefy the solution. Therefore, the final concentration of PVA16000 (0.03%, w/v) was lower than other additives used (from 0.06% to 1.2%, w/v). Concentrations higher than 0.03% (w/v) generated extremely viscous solutions and thus were not investigated. Characterization of Particle Size and Shape It has been previously reported that the micrometric properties of engineered crystals (e.g. size and shape) could differ significantly by using a small amount of an ‘effective additive’ (Davey, 1982). Particle size distribution (PSD) for commercial xylitol and crystallized xylitol in the presence or the absence of different additives varied considerably

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