Salih Dinçer

Supercritical-fluid extraction of essential oil from Turkish lavender flowers☆

Abstract Essential oil was extracted from Turkish lavender flowers by supercritical carbon dioxide. A statistical experimental design based on “Second Order Central Composite Design” was planned fixing the extraction period at four hours. Parameters such as pressure, temperature, carbon dioxide flow rate, and particle size coded as x1, x2, x3, and x4, respectively, were used. These parameters were investigated in five levels (−2, −1, 0, 1, and 2). The dependent variable Y1 was taken as the relative overall essential oil yield. The effects of operating conditions of supercritical fluid extraction on the relative overall yields were calculated with respect to steam distillation. The optimum conditions to obtain Y ≥ 80% were about x1 = 85.77 bar, x2 = 36.58 °C, x3 = 10.11 L h−1, and x4 = −2143 μm, after some modifications for third order-like model. The components of lavender essential oil such as fenchone, camphor, linalool, linalyl acetate, bornyl acetate, and cadinene were detected by GC-MS chromatography. Fenchone and camphor were determined as the major components. Besides, the essential oil samples extracted and trapped in alcohol for each experiment were analyzed qualitatively by gas-liquid chromatography. Then, the same response surface methodology was used for components of essential oil such as fenchone (Y2) and camphor (Y3).

Pervaporation of methanol-methyl acetate binary mixtures

Abstract In this study, the pervaporation behaviour of azeotrope forming methanol–methyl acetate binary mixtures of different compositions was investigated at 30 and 45°C using cuprophane membranes. Experimental fluxes and selectivities of the permeating components were determined and evaluated on the basis of the feed mixtures and membranes. The effect of vacuum pressure on total flux and selectivity is discussed.

Coprocessing of a Turkish lignite with a cellulosic waste material: 3. A statistical study on product yields and total conversion

The objectives of this study were to evaluate statistically the effects of coprocessing parameters on liquefaction yields, to determine the key process variables affecting the oil+gas, oil and asphaltene yields and total conversion. A statistical experimental design based on Second Order Central Composite Desing was planned fixing the liquefaction period at 1 h. Parameters such as temperature, initial cold pressure, tetralin/(lignite+sawdust) and sawdust/lignite ratios coded as x1, x2, x3 and x4, respectively, were used. The parameters were investigated at five levels (−2, −1, 0, 1 and 2). The effects of these factors on dependent variables, namely, oil+gas, oil and asphaltene yields and total conversion were investigated. To determine the significance of effects, the analysis of variance with 99.9% confidence limits was used. It was shown that within the experimental ranges examined, temperature and sawdust/lignite ratio were the variables of highest significance for oil+gas yields, oil yields and total conversion.

Sorption behavior and preliminary pervaporation results of cross-linked polyvinylalcohol and polydimethylsiloxane membranes prepared for the separation of water-ethylacetate mixtures

Since pervaporation process is the coupling of solution and diffusion mechanisms, a sorption study was carried out with membranes prepared by cross-linking polyvinylalcohol (PVA) and polidimethylsiloxane (PDMS). Tartaric acid (Tac) was used as the cross-linking agent for PVA, and a commercial cross-linking agent was used for PDMS. Sorption experiments were carried out at 30-50°C temperature range in pure water and ethyl acetate using the films prepared. The PVA and PDMS films prepared preferentially sorb water and ethylacetate, respectively. A pervaporation study at 30°C was carried out for pure ethylacetate and pure water, and mixtures of ethylacetate containing 2 and 2.5 wt% water using 100 w m thick PVA membrane. The results indicate that the PVA membrane prepared is extremely selective for water.

Supercritical Fluid Extraction of Lavandula stoechas L. ssp. cariensis (Boiss.) Rozeira

Abstract The flowers of Lavandula stoechas L. ssp. cariensis (Boiss.) Rozeira were extracted in both a batch and semi-continuous system by supercritical CO2. In the first stage, experiments were performed in a batch system based on response surface methodology (RSM). Parameters used were pressure, temperature, mixing speed and extraction time, and were coded as, X1, X2, X3 and X4, respectively. These parameters were investigated at three levels (-1,0 and 1). The dependent variable, Y, was taken as the volatile concentrate yield of supercritical fluid extraction. It was calculated with respect to the yield of solvent extraction by dichloromethane. In the second stage, experiments were carried out in a semi-continuous system at constant pressure and temperature, and different CO2 flow rates. Concentrations of volatile components were determined as a function of extraction time and CO2 residence time

Application for pinch design of heat exchanger networks by use of a computer code employing an improved problem algorithm table

In this work, the methods used in pinch design were applied to a heat exchanger network with the aid of an improved problem algorithm table. This table enables one to compose composite and grand composite curves in a simplified way. A user friendly computer code entitled DarboTEK, compiled by using Visual Basic 3.0, was developed for the design of integrated heat exchanger networks and estimation of related capital costs. Based on the data obtained from the TUPRAŞ petroleum refinery at Izmit, a retrofit design of heat exchanger networks was accomplished using DarboTEK. An investment of

Liquefaction of Turkish lignites and asphaltites with a Turkish vacuum residual oil

3,576,627 is needed which will be paid back in 1.69 years simply by energy conservation due to heat integration.

DESORPTION OF ETHYL ACETATE-WATER MIXTURE BY USING CROSS-LINKED POLY(VINYLALCOHOL) MEMBRANE AND COMPARISON OF RESULTS WITH PERVAPORATION

Abstract Liquefaction studies in a magnetically stirred autoclave were carried out using different types of lignite and asphaltite. Tupras vacuum residue oil was coprocessed with Beysehir, Cayirhan, Goynuk, Keles and Orhaneli lignites, and Silopi and Şirnak asphaltites. Coprocessing was performed under liquefaction conditions of 2:1 solvent:lignite or asphaltite ratio, 440°C, 80 atm hydrogen pressure for 1 hour reaction time. Total conversions ranging from 40.3 to 92.1% (d.a.f.) for both lignites and asphaltites were obtained. A comparison of liquefaction yields obtained in vacuum residue oil with those obtained using tetralin or anthracene and creosote oils as solvent, under the same operation conditions, was made.

Phase behaviour of essential oil components in supercritical carbon dioxide

In this study using poly(vinylalcohol) (PVOH) membranes cross-linked with tartaric acid (Tac) desorption experiments were performed for selected concentrations of binary ethyl acetate (EtAc)-water mixture at temperatures of 30°, 40°, and 50°C to determine sorption of components. Sorption values measured were compared with those estimated by the Flory-Huggins approach. Additionally, desorption results were compared with pervaporation results of another study in terms of solution-diffusion theory, and the effect of thermodynamic interactions on selective transport of the binary mixture and membrane system was investigated. The results obtained show that selective transport of EtAc-water mixture was influenced by increasing temperature and water content in the feed. It is shown that preferential sorption is more effective for pervaporation selectivity than diffusion selectivity.