A Novel Spherical Crystallization Method Using Pickering Emulsions

Area of Science:

• Chemical Engineering
• Crystallization Science
• Colloid and Surface Chemistry

Background:

• Spherical crystallization is a key process intensification technique.
• Surfactants are crucial but pose toxicological concerns, necessitating alternatives.
• Pickering emulsions offer a potential surfactant-free approach.

Purpose of the Study:

• To investigate the use of colloidal particle-stabilized Pickering emulsions for spherical crystallization.
• To eliminate or significantly reduce surfactant usage in crystallization processes.
• To enhance Pickering emulsion stability using depletion attraction for improved crystallization control.

Main Methods:

• Preparation of silica nanoparticles to stabilize oil-in-water emulsions.
• Evaporative crystallization of ibuprofen within stabilized Pickering emulsions.
• Application of depletion attraction using polyethylene glycol (PEG) and polyvinyl alcohol (PVA) to enhance emulsion stability.
• Comparison of crystal products obtained using silica nanoparticles versus a conventional non-ionic surfactant (Tween 20).

Main Results:

• Depletion attraction effectively stabilized Pickering emulsions, enabling high dispersed phase fractions.
• Mono-dispersed ibuprofen spherical agglomerates were successfully produced.
• Silica nanoparticles reduced crystallization induction time by promoting heterogeneous nucleation.
• Steric effects from nanoparticles potentially mitigated secondary agglomeration.

Conclusions:

• Pickering emulsions stabilized by silica nanoparticles are a viable alternative to surfactant-stabilized systems for spherical crystallization.
• Depletion attraction significantly improves Pickering emulsion stability and crystallization product morphology.
• Silica nanoparticles offer advantages in nucleation and agglomeration control, reducing reliance on traditional surfactants.