Continuous steam distillation

Gum turpentine is obtained from wounding living trees to get an exudate containing turpentine and rosin. Turpentine is separated from the rosin by continuous steam distillation and further fractionation. Wood turpentine comes from the extraction of stumps of pine trees using naphtha, and subsequent separation of rosin and turpentine by fractional distillation. Tail-oil turpentine is a byproduct of the Kraft sulphate paper manufacture. Terpenes are isolated from the sulphate terpentine and separated from the black digestion liquor. The composition of turpentine oils depends on its source, although a-pinene and p-pinene are the major components. 

Fig. II, 41, 4 is an apparatus for the continuous steam distillation of a liquid which is heavier than water. The aqueous mixture is placed in the flask A of relatively large capacity the receiver B consists of a distilling flask (provided with a stopcock at the lower end), the capacity of which is less than the volume of the liquid in A, and is placed several inches higher than the opening in the wide vertical tube C. The lower end of the funnel D must-be below the side arm of the receiver in order to prevent bubbles of the heavy liquid from collecting on the surface of the steam distillate and being carried back to the flask A. The rubber tube E for the returning aqueous liquor must at some point be lower than the entrance to the tube C so that a trap of liquid will be formed and prevent the vapours from A entering the side tube.

Figure 8.3 Apparatus used for sample preparation involving distillation or sublimation. A, distillation apparatus for organic volatiles in water B, micro apparatus for continuous steam distillation with continuous llquid-llguid extraction of the distillate C, micro sublimation appeuratus.

Continuous steam distillation, 147, 148 Cooling baths, 61 Cooling curve method, 26 Copper bronze, activated, 193 Copper - chromium oxide catalyst, for aldehyde synthesis, 318, 321 for hydrogenation, 872, 873 hydrogenolysis with, 872J Copper phthalocyanine, 983 Copper powder, 192 Copper sulphate, as desiccant, 40, 41 Cork stoppers, 55 boring of, 56... 

Continuous Steam Distillation.—The apparatus (Fig. 16) is very convenient when this process has to be carried on for some time. The substance to be steam distilled is placed in the round-bottomed flask A along with water if none is present. To the flask is attached through a cork a tube delivering to a vertical tube B, and with a small side tube C. A... 

In continuous steam distillation, an insulated conveying system with superheated steam as carrier is used for providing a countercurrent flow of steam and pulverised plant material. During transport, the oil is transferred into the vapour phase and exits the system with the steam. A cyclonic vessel separates the gas phase from the solid phase. In the last step the gas phase (steam and oil) is condensed, the oil is separated using a Florentine flask and the water recycled to the boiler [27]. 

Steam distillation is also a very simple and effective method for the purification or deodorisation of high-boiling organic substances (e.g. essential oils). In the food industry, fats or fatty acids are deodorised and decolourised with steam. Continuous steam distillation in a column is used for this purpose. In this operation, the heated oil is run as a thin film countercurrently to the steam this reduces the amount of steam... 

Boucard G., Serth R., Continuous Steam Distillation of Essential Oils, Perf Flav., 23,3/4 (1998)... 

Teranishni, R., Keller, U., Flath, R.A., and Mon, T.R., Comparison of batchwise and continuous steam distillation—solvent extraction recovery of volatiles from oleoresin capsicum, African type (capsicum frutesens), J. Agric. Food Chem., 28, 156, 1980. 

Dll. We are doing a single-stage, continuous steam distillation of 1-octanol. The unit operates at 760 mm Hg. The steam distillation is operated with liquid water present. The distillate vapor is condensed and two immiscible liquid layers form. The entering organic stream is 90.0 mol% octanol and the rest is nonvolatile conpounds. Flow rate of feed is 1.0 kmol/h. We desire to recover 95% of the octanol. 

D15. We wish to use continuous steam distillation to recover 1-octanol from 100 kg h of a mixture that is 15 wt % 1-octanol and the remainder consists of nonvolatile organics and solids of unknown composition. The feed will be preheated to the same temperature as the still pot, which operates at 1.0 atm pressure. The pot is operated with liquid water in the pot. Assume the still pot is well mixed and liquid and vapor are in equilibrium Ninety-five percent of the 1-octanol should be recovered in the distillate. Assume that water is completely immiscible with 1-octanol and with the non-volatile organics. Because the conposition of the non-volatile organics is not known, we do a simple experiment and boil the feed mixture under a vacuum with no water present. The result is at 0.05 atm pressure the mixture boils at 129.8°C. 

Note We will see in Problem 9.E2 that batch steam distillation requires less steam than continuous steam distillation. 

During most of the batch operation, the mole fraction of the volatile organic is considerably higher than it is at the end of the batch. In continuous steam distillation the mole fraction of the volatile organic is always at its lowest value. Thus, batch steam distillation requires less steam for a given separation than continuous steam distillation. 

Steam distillation A Bleidner apparatus can be used for the extraction of aromatic amines. In this system, a continuous steam distillation or continuous LLE is carried out and good recoveries are obtained (over 90%). The extraction solvent is isooctane and the extraction time is 2-3 h the technique is not laborious. Steam distillation extraction can be used quantitatively for different types of organic substances at microgram per liter to nanogram per liter levels. Good results can be obtained within 20 min. Steam distillation results in a cleaner extract and reduces the build-up of residue at the GC column. The small volumes of solvent normally used in steam distillation techniques facilitate solvent concentration and minimize interferences due to solvent impurities. 

Continuous steam distillation combined with continuous extraction of the distillate with cyclohexane or isooctane is the most effective technique for separation of nonylphenol and its low mole EO adducts from water (106). Since isooctane has the higher boiling point, it is more suitable for recovery of the 1- and 2-mole adducts than is cyclohexane (118). The separation is nearly quantitative for homologs up to n = 3, with recovery dropping to only 24% for = 6 (119). 

NPE, E = 0-7 ethoxy distribution Sewage influent and effluent Continuous steam distillation/ liquid-liquid extraction with cyclohexane Normal phase HPLC-UV (277 nm) 119... 

Continuous steam distillation/solvent extraction (cyclohexane) alumina cleanup (CH2CI2 elution)... 

Jahda and Marha [160] investigated the isolation of s-triazines from water using continuous steam-distillation extraction prior to gas-liquid chromatography. Recoveries of seven triazine herbicides, Propazine, Terbutylazine, Atrazine, Prometryne, Terbutryne, Desmetryne and Simazine from water at pH values of 5, 7 and 9 are reported. Recovery rates were independent of pH but generally improved with increase in time of steam-distillation extraction from 1 to 3h. Low recovery rates were obtained for Simazine. Atrazine only gave good recovery rates after 3h steam-distillation extraction. 

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