Continuous Water Circulation Distillation A Modification of Steam Distillation D. B. Gujarathi and N. T. May1 Sangamner College, Sangamner, Pin-422 605, lndia
In the conventional steam distillation ( I ) , a steam generator is used, and the steam is passed through the flask mntaining the swam-volatile compounds in the mixed forms. Due to latent heat of steam. the steam-volatile comnound undergoes evaporation. It requires frequent addition of water in the steam eenerator. Secondlv. the contents of the flask containing steam-volatile compokds may elevate or eo hevond caoacitv. so that the steam distillation work " needs interruption. To overcome all these difficulties, a CWCD2unit can be used for separating steam-volatile substances fmm complex mixtures or natural sources.
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Working Details The CWCD unit is depicted in the figure. The mixture containine steam-volatile comnounds is transferred to the amount of water is added, distillati& flask A. ~ s u f f i c i e & and the contents are heated. The water vapor along with steam-volatile compounds are carried through the rubber tube to the condensor C.3 The flask B containing water links the extractor E4 and side tube F. The condensate drops down into the extractor E that contains extractanL5 The steam-volatile compound, being soluble in the extractant, gets extracted while the surplus water drops are transferred into the flask A with the help of side tube F. The same cycle goes on until the heating is discontinued. The system is equipped with vent D as shown to relieve pressure developed during overheating. Performance The CWCD unit has been used for isolation of curcumin from rhizomes of Curcumalonga linn. About 450 mg
'The work was performed oy N.T. llay in panial fulfilmentof BSc Degree under Restrunur~ng Lnlversry of Poona. Pune.Programme, . 411007, lndia. 'CWCD means Continuous Water Circulation Distillation. 3The condensor is prepared by using 112-in. PVC pipe and 5 mm glass tubing and rubber corks. 4Theearactor E is prepared from cutting the stem of air condensor SO that the lower end will just touch the bottom d flask B. =Theextractant should be water immiscible and its specific gravity should be less than one; e.g., ethyl acetate.
86
Journal of Chemical Education
Continuous Water Circulation Distillation (CWCD)unit.A - Distillation Flask; B - Round bottom Flask; C - Condenser; D -Vent; E - Extractor; F - Side Tube. curcumin has been isolated from 20 g turmeric powder using ethyl acetate (10 mL) as an extractant and utilizing the above assembly. Literature Cited 1.Roger.V. et el. Vogpl's 'ktbook afOIganicPmetimI Ckmisby, 4thed.;hdon:Lmgman. 1978.
