Solvent crystallization of palm based dihydroxystearic acid with isopropyl alcohol: Effects of solvent quantity and concentration on particle size distribution, crystal habit and morphology, and resultant crystal purity

Crude dihydroxystearic acid was prepared from palm based oleic acid and was then solvent purified with isopropyl alcohol in a custom fabricated simultaneous batch crystallizer unit. The crystallized dihydroxystearic acid was a functional ingredient that acted as multipurpose intermediate for synthesis of various fine chemicals, cosmetics and personal care products. The effects of solvent quantity and concentration on particle size distribution, crystal habit and morphology, and resultant crystal purity were studied. The crystals were purer but smaller and the span of the distribution curve was wider at higher solvent quantity and concentration. Through scanning electron microscopy and X-ray diffraction, it was observed that the crystals agglomerated into plate-like (flaky) habit with triclinic crystal structure. Solvent crystallization with 80% IPA at 20 °C and solute:solvent ratio of 1.0:1.0 was the most optimized and efficient, producing β-DHSA crystals that has high resistance against fat exudation during vacuum filtration process.

Crude dihydroxystearic acid was prepared from palm based oleic acid and was then solvent purified with isopropyl alcohol in a custom fabricated simultaneous batch crystallizer unit. The effects of solvent quantity and concentration on particle size distribution, crystal habit and morphology, and resultant crystal purity were studied. It was observed that the crystals agglomerated into plate-like (flaky) habit that grew in a layer-by-layer fashion. The flower-like triclinic crystal structure was similar to that of desert rose structure occurred among gypsum and barite crystals in arid areas. The desert rose were semi-spherical radiating rose-like rosette aggregates of platy barite crystals.Figure optionsDownload as PowerPoint slideHighlights
► Palm DHSA is a multipurpose functional ingredient in various consumer products.
► Solvent crystallization of DHSA is optimized with 80% IPA; 20 °C; DHSA:IPA 1.0:1.0.
► β-Polymorph DHSA crystal is desired for its high resistant against fat exudation.
► Optimized filtration is precursor to full scale mass production of DHSA crystals.