Isopropanol/water mixture, separation

To cope with matrix effects, and to achieve some enrichment, suitable separation methods can be applied, e.g. solvent extraction, coprecipitation, or volatilization directly from the inorganic solid sample (Heinrichs, 1979 Han et al., 1982 Sager, 1984). As the volatility of organic chelates is low, and the volatility of halogenides from organic solvents remains the same, organic phases obtained from solvent extractions have been put directly into the furnace. In this case, however, carry-over in the autosampler has to be prevented by an organic soivent, at ieast by an isopropanol/water mixture. 

Anjali Devi, D., Smitha, B., Sridhar, S., and Aminbhavi, T. M. 2005. Pervaporation separation of isopropanol/water mixtures through cross-linked chitosan membranes. J. Membr. Sci. 262 91-99. 

Nawawi, M.G.B.M. and Hassan, H.B. 2003. Pervaporation separation of isopropanol-water mixtures using crosslinked chitosan membranes. J. Teknol. 39(A) (Keluaran Khas Dis) 55-64. 

The azeotropic composition of a binary system is not only influenced by recycled third components added to the mixture and by the operating pressure, but also by the presence of an insoluble inert gas, which is favorable for the separation if the volatile components of the mixture diffuse at different velocities across the regions of inert gases. Figure 2-31 a shows an example using the binary isopropanol/water mixture. Steam diffuses faster across an air bolster than isopropanol vapor, and thus, the distillate of isopropanol mole fraction is more water-rich due to the presence of air between the liquid and the condensation surfaces (point A2), compared with the distillation under air exclusion (point A,). 

The shifting of A] A2 is of practical use in separating water rich isopropanol/water mixtures (Fig. 2-31 b). A feed/"is almost completely separated into water flow rate JV leaving column DCl and a isopropanol flow rate P leaving column DC2. Both columns are operated at ambient pressure. The overhead products AT, and JC2 are practically of azeotropic composition (point Aj, Fig. 2-31 a). In the condenser C, most of the condensed overhead products form the reflux / , or / 2, to the columns DCl or DC2, respectively. The remainder is then separated into a water rich fraction >i and an alcohol rich fraction >2 in the diffusion distillation unit DA (Fig. 2-31 c shows the diffusion separation unit). Some of the overhead product fluxes Kj and K2 are heating the unit while water is used for cooling. 

Separation of an isopropanol/water mixture by azeotropic rectification using toluolene, reduction of energy costs to 70% of these compared to conventional operation by means of a heat pump IPA Isopropanol P Power Q Heat flow... 

In Part 3 of this book an extrainer is added to the system so that liquid-liquid sphtting can appear in the top decanter and also maybe in the top few stages of the azeotropic column. The LLE behavior in the decanter, or the VLLE behavior in the top stages of flie azeotropic column, can be predicted by Aspen Plus. The system of separating an isopropanol-water mixture using cyclohexane as the entrainer will be used as an example to demonstrate the way to generate a LLE envelope in Aspen Plus. 

P. Zhang, J. Qian, Y. Yang, Q. An, X. Liu, Z. Gui, Polyelectrolyte layer-by-layer self-assembly enhanced by electric held and their multilayer membranes for separating isopropanol-water mixtures. Journal of Membrane Science, 320 (2008) 73-77. 

Fonr mobile phases (mixtures of chloroform, isobutanol, isopropanol, water, and acetic acid) separately and in combination... 

Hybrid membranes composed of poly(vinyl alcohol) (PVA) and tetraethylorthosilicate (TEOS), synthetised via hydrolysis and a co-condensation reaction for the pervaporation separation of water-isopropanol mixtures has also been reported [32], These hybrid membranes show a significant improvement in the membrane performance for water-isopropanol mixture separation. The separation factor increased drastically upon increasing the crosslinking (TEOS) density due to a reduction of free volume and increased chain stiffness. However, the separation factor decreased drastically when PVA was crosslinked with the highest amount of TEOS (mass ratio of TEOS to PVA is 2 1). The highest separation selectivity is found to be 900 for PVA TEOS (1.5 1 w/w) at 30°C. For all membranes, the selectivity decreased drastically up to 20 mass % of water in the feed and then remained almost constant beyond 20 mass %, signifying that the separation selectivity is much influenced at lower composition of water in the feed. 

In view of the very high reactivity of the aminochromes in solution, paper chromatographic studies with these compounds present a number of difficulties. For instance, the ease with which the aminochromes may interact with the solvent system being used, or with impurities in the paper, must be taken into consideration. One of the solvent systems which has been extensively employed for the paper chromatographic separation of aromatic compounds (i.e. an isopropanol-ammonia-water mixture) is quite unsatisfactory in this case, since, in the experience of the author, total decomposition of the aminochromes in basic solvents invariably occurs very rapidly.64 This is not surprising in view of the known sensitivity of the amino-... 

Z,Z)-Bis[2-phenylethenyl] Ditellnrium2 6.4 g (50 mmol) tellurium, 42 g (750 mmol) potassium hydroxide. 22.6 g (100 mmol) tin(II) chloride dihydrate, 10,2 g(100 mmol) phenylacetylene, 20 ml toluene, 60 ml water, and 1.2 g Adogen 464 are vigorously stirred and kept at 80° to 97° for 7 h. The organic layer is separated and the aqueous layer is extracted with benzene. The benzene is evaporated under reduced pressure and the residue dissolved in a small volume of diethyl ether. This solution is poured into 200 m/ isopropanol. The mixture is kept in the refrigerator for 3 days. The yellow crystals of the bis[2-phenylethenyl] tellurium are separated from the red needles of the ditellurium compound, that melted at 82 (yield 6%). 

Toxic trace elements were isolated from water samples by extraction with di-ethyldithiocarbamate (Table 2.1.2). Following this pre-concentration step the metal ions were adsorbed on a cation-exchange resin using a mixture of tetrahydro-furan-methylglycol-6 M HCl as sorption solution. The succesive elution was treated with 6 M HCl, 1 M HCl and 2 M HNO3 for fractional separation. In another application hexane-isopropanol-HCl mixture was used as the adsorption medium An analytical scheme which provides quantitative results, is described for ion-exchange separation of fifteen major, minor and trace elements in silicates For concentration and separation of copper, chromium, lead and iron an ion-exchanger in phosphate or OH -form was used in various combinations ... 

For heterogeneous batch distillation a new double column configuration operating in closed system is suggested. This configuration is investigated by feasibility studies based on the assumption of maximal separation and is compared with the traditional batch rectifier. The calculations are performed for a binary (n-butanol - water) and for a ternary heteroazeotropic mixture (isopropanol - water + benzene as entrainer). Keywords heteroazeotrope, batch distillation, feasibility studies. 

The pervaporation dehydration study of isopropanol-water and ethanol-water mixtures was carried out by Moon et al. [90]. The two-ply dense composite membranes were prepared using successive castings of sodium alginate and CS solutions. The membranes showed improved mechanical strength, flux, and separation factor. The three factors like polymer type contacting the feed stream, NaOH treatment, and type of cross-linking agent decide the flux and separation factor of the two-ply membrane system. 

PV using PVA membranes were studied extensively (Yeom and Lee 1996 Li et al. 2007 Rhim et al. 2002). Nonporous PVA membranes were modified in gaseous plasma to improve the separation efficiency for water-isopropanol (IPA) mixtures via PV. Membranes were exposed to the plasma of air, nitrogen, and oxygen for 2-15 min and their performance was evaluated at 75°C. Modification of membranes in a nitrogen plasma environment leads to increase in selectivity by about 1477 at 25°C. The cross-linking on the membrane surface induced by the plasma was found to be responsible for the observed improvement (Upadhyay and Bhat 2004). 

Bidimensional TLC studies have been done using silica gel as the sorbent. For instance, Lando et al. (1967) separated apurinic DNA oligonucleotides on silica gel with an isopropanol-water (75 25) mobile phase in the first direction and butanol-acetic acid-0.5% ammonia (90 30 40) in the second direction. Thymus DNA was separated into 21 spots, of which 16 were identified as nucleotides by UV spectrophotometry following enzymatic treatment. Issaq et al. (1977) used 2D-TLC on silica gel to separate a mixture of 19 adenine and uracil bases. Chloroform-methanol (90 10) was used for the first dimension and chloroform-propanol (90 30) for the second. 

We will start this chapter by explaining how the heterogeneous azeotropic distillation works in separating a mixture with an azeotrope. Three systems with different RCMs will be used as examples to illustrate the column sequence for the separation. After that, we will focus on the detailed design and control of the isopropanol-water system, which is a system that exhibits the most complex RCM. 

Thiamin may be extracted from tissues, foodstuffs or pharmaceutical preparations with aqueous alcohol mixtures at a pH of 4-6 and separated from closely related compounds and metabolites by TLC on cellulose layers or silica gel. Various mobile phases have been used, including isopropanol-water-trichloracetic acid-ammonia (71 9 20 0.3) and butan-l-ol-acetic acid-water (40 10 50) (1). Thiamin may be separated from its hydrolysis and oxidation products by TLC/densitometry (2) and other chromatographic techniques have been reviewed (3). Sandwich-type chambers afford rapid... 

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