Separation of the Azeotrope (Allyl Alcohol + Water) using Naturally Derived Solvents and their comparison with other Extractive Reagents

Chemical Engineering

Azeotropes are formed when two chemical species form close-boiling mixtures, such that the mixture becomes inseparable by simple distillation, and also cause excessive pressure drop and pressure loss in the system, which results in energy losses. Allyl Alcohol forms a positively – deviating azeotrope with water. Since conventional distillation techniques would get ruled out here, it calls for a more radical approach to separation, which can be achieved by the use of entrainers, like organic solvents and ionic liquids. But these entrainers are environmentally hazardous and expensive. An alternative to these entrainers are environment-friendly extractive reagents - Natural Deep Eutectic Solvents, having far less environmental impacts and are significantly cost-effective compared to other azeotrope breakers. The isobaric vapour-liquid distillation experiment was carried out using Natural Deep Eutectic Solvents, at a pressure of 101.325 kPa in a Vapour-Liquid Equilibrium Distillation apparatus. The separation was initially accomplished by a common salt - Calcium Chloride, followed by the Natural Deep Eutectic Solvent (5 g), which was reported to reduce the boiling point of allyl alcohol by at least 15 ͦC, thereby facilitating effective separation of the allyl alcohol - water binary azeotrope. Eventually, the separation was done using the indigenously prepared bio-derived solvent which essentially consists of a mixture of glycerol and sun-dried orange peels, which were then crushed into a powder, and the two substances were mixed in pre-defined quantities and stirred to form a paste-like mixture. The consistency of VLE data was checked through the ‘Slope of ln ϒ- curve’ and the ‘Redlich-Kister’ consistency tests.

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