Quantitation of the amount of finish applied during fiber manufacturing is an important industrial quality control process. Finish levels that are too low result in excessive fiber and mechanical wear. On the other hand, overly high finish levels may cause residue buildup on the processing equipment. Removal of the finish has traditionally been done with solvents such as chloroform or Freon followed by gravimetric or spectroscopic analysis of the removed material. Quantitation of low molecular weight oligomeric material is another important quality control practice for the fiber industry in that the presence of these species and their concentration affect the physical properties of the polymer. Also, excessively high concentrations of oligomers may result in residue deposits on processing equipment. Typical conventional methods for determining the concentration of oligomers present in fibers involve large quantities of organic solvent for removal of the oligomers followed by chromatographic analysis. Increased government regulation of chlorinated and other solvents has led to investigations of alternate methods of extraction. Several studies have shown that supercritical fluid extraction (SFE) using carbon dioxide as the extraction fluid is an important alternative to conventional organic solvent extraction for the removal of both textile finishes and oligomeric material. This research seeks to extend the previous studies regarding the application of SFE for the quantitation of finish and oligomers from nylon 6,6 fibers. The effects of pressure, extraction temperature, modifier percentage, static extraction time, and dynamic extraction time on the supercritical fluid extraction efficiency of nylon 6,6 oligomers were examined. Results from the SFE methods for both finish and oligomer extractions were compared to results from conventional solvent extraction. The extracted oligomers were identified by HPLC with coupled on-line atmospheric pressure chemical ionization mass spectrometry (APCI-MS) and HPLC fractionation coupled with off-line Liquid Secondary Ion Mass Spectrometry (LSIMS). / Master of Science

No description available.

Three types of nonlinear optical spectroscopies, ultrafast two-dimensional infrared (2DIR) spectroscopy, transient infrared (IR) absorption/pump-probe spectroscopy, and sum-frequency generation (SFG) vibrational spectroscopy, are used to investigate molecular structure and dynamics in two distinct classes of materials. First, 2DIR and pump-probe spectroscopies are used to study ultrafast rotational and vibrational energy relaxation in dense gaseous and supercritical fluid solutions, special solvation effects near the critical point, and the evolution of cooperative, liquid-phase dynamics as a function of density for two different solvent systems. 2DIR’s demonstrated capabilities offer a unique tool for identifying co-existing free rotor and liquid-like populations within the same fluid sample, evaluating the adequacy of isolated binary collision (IBC) relaxation descriptions in dense gas and near-liquid density fluids, and learning about how solute-solvent intermolecular properties separately influence rotational and vibrational relaxation in these dynamic and heterogeneous environments. Analysis of the density-dependent 2DIR and pump-probe spectra of a quasi-free rotor (asymmetric stretch rovibrational band of N2O) in SF6 and Xe provides timescales for rotational energy relaxation rates (1 – 3 collisions), but much slower vibrational energy relaxation rates. A critical slowing effect on the rate of rotational relaxation is identified, and liquid-like solvation is observed in dense gaseous solutions at state points lower than the critical density. Solvent-dependent differences in energy relaxation and IBC model breakdown, as well as applications of this 2DIR methodology to other high density and supercritical solution dynamics and descriptions are discussed. In a second nonlinear spectroscopy project, SFG is used to study the role of substrate type, gold or silver, and surface roughness on the parity odd-even effect in n-alkanethiolate (n = 10 – 16) self-assembled monolayers (SAMs), materials of potential importance to molecular scale electronics. SFG methyl vibrational transition intensities, frequencies, and linewidths display parity and metal dependence attributable to the orientational differences of the interfacial ethyl group, which inverts for SAMs on Ag substrates relative to SAMs on Au. Substrate roughness, an often-underreported experimental parameter, is shown here to affect the extent of odd-even methyl orientation anisotropy, and this SFG analysis establishes a new roughness limit for the appearance of odd-even effects on Ag substrates.

The purpose of this research was to design a simple, novel interface for on-line coupling of Supercritical Fluid Extraction (SFE) with High Performance Reversed Phase Liquid Chromatography (HP-RPLC), and to explore its ability for quantitative analysis of analytes in different matrices. First, a simple interface was developed via a single one six-port injection valve to connect the SFE and LC systems. A water displacement method was utilized to eliminate decompressed CO2 gas in the solid phase SFE trap and connection tubes. To evalute this novel hyphenated system, spiked polynuclear aromatic hydrocarbons (PAHs) in a sand matrix were used as target analytes with the achievement of quantitative results. Also PAHs in naturally contaminated soil were successfully extracted and quantitatively determined by this hyphenated system. Compared to the EPA method (Soxhlet extraction followed by GC-MS), on-line SFE-LC gave precise (4-10% RSD) and accurate results in a much shorter time. Based on this hyphenated technique, a method for the extraction and analysis of hyperforin in St. John's Wort was developed under air/light free conditions. Hyperforin is a major active constituent in the antidepression herbal medicine-Hypericum Perforatum (St. John's Wort). Hyperforin is very sensitive to oxygen and light. There is no way to date to determine whether any degradation occurs during the sample-processing step in the analytical laboratory. On-line coupling of SFE-LC with UV absorbance/ electrospray ionization mass spectrometry (SFE-LC-UV/ESI-MS) provided an air/light free extraction-separation-detection system, which addressed this issue. Mass spectral data on the extract confirmed the presence of the major degradation compounds of hyperforin (i.e. furohyperforin and two of its analogues). Thus, the degradation process must have occurred during plant drying or storage. The feasibility of quantitative extraction and analysis of hyperforin by on-line SFE-LC was made possible by optimizing the extraction pressure, temperature, and modifier content. High SFE recovery (~90%) relative to liquid-solid extraction was achieved under optimized conditions. We then extended the interface's application to an aqueous sample by using a liquid-fluid extraction vessel. Quantitative extraction and transfer were achieved for the target analytes (progesterone, phenanthrene, and pyrene) spiked in water, as well as in real samples (urine and environmental water). During each extraction, no restrictor plugging was realized. Extraction temperature and pressure were optimized. Different amounts of salt were added to the aqueous matrix to enhance ionic strength and thus extraction efficiency. Methanol and 2-propanol were used as CO2 modifiers. Two modifier modes were compared, e.g. dynamically mixing modifier with the CO2 extraction fluid, and pre-spiking modifier in the extraction vessel. Surprisingly, we found pre-spiking the same amount of modifier in the vessel enhanced the recovery from ~70% to ~100% for progesterone, phenanthrene, and pyrene due to a "co-extraction effect". The last phase of our work explored the disadvantages/limitations of this hyphenated technique through the analysis of more highly polar phenolic compounds in grape seeds. Five types of SFE trapping adsorbent materials were evaluated in an effort to enhance the collection efficiency for the polar components. Pure supercritical CO2 was used first to remove the less polar oil in the seeds. Then methanol-modified CO2 was used to remove the polar components (e.g. phenolic compounds). Catechin and epicatechin (90%) were exhaustively extracted out of the de-oiled seed after 240 minutes with 40% methanol as modifier. Both singly linked (B-type) and doubly linked (A-type) procyanidins were identified by LC-ESI-MS, as well as their galloylated derivatives. Compared to the off-line SFE-LC approach, much less sample was required for extraction in the on-line method, since all the extracted components could be transferred to the LC column. Also, no extract processing/concentration step was needed in the on-line method. However, in the on-line mode, some polar compounds were lost (1) during the collection step (e.g. lower trapping efficiency on a single solid SFE trap when a high percentage modifier was used) and (2) during the water rinsing step (e.g. less retention of polar compounds on C18 trap). Therefore, this hyphenated technique is less desirable for the analysis of highly polar compounds. / Ph. D.

Supercritical fluid extraction (SFE) continues to be explored as a feasible alternative to traditional Soxhlet and other types of extraction. In many cases SFE is cleaner, faster, and less expensive than the traditional types of extractions. This investigation has focused on the evaluation of Supercritical CO₂ extraction as a quantitative method for recovery of a hypolipidemic drug (tradename xenalipin) from an animal feed matrix. Initial emphasis of this study focused on the recovery of xenalipin from a the animal feed matrix employing a liquid solvent trap. By studying the effect of time of extraction versus recovery of drug, the liquid trap was shown to be inadequate. Further studies implemented the extraction of xenalipin from a filter paper matrix and the use of solid phase traps. This method of inquiry was use to evaluate the degree of recovery as related to the parameters of CO₂ density, extraction time, and flow rates of CO₂. After achieving quantitative extraction of xenalipin from filter these parameters were transferred to the animal feed matrix. The animal feed matrix was prepared using three different methods. Each matrix was evaluated for homogeneity of sample and ability to achieve quantitative extraction. / Master of Science

The extraction of fifteen (15) polymer additives with supercritical carbon dioxide which are used as antioxidants, uv stabilizers, process lubes, flame retardants and antistats from eight formulations of polystyrene is demonstrated and compared to traditional dissolution/precipitation extractions. The purpose of the study was twofold: 1) the development of a high performance liquid chromatography (HPLC) method(s) for the additives and 2) the determination of the viability of supercritical fluid extraction (SFE) for the additives from polystyrene. Separation of some of the additives was achieved using reversed phase liquid chromatography. Nine of the additives were assayed in this manner while, the remaining six additives could not be assayed using reversed phase liquid chromatography. In order to develop an extraction method for the additives, the effects of static extraction time, CO2 density, and temperature were first investigated. These preliminary extractions revealed that a static extraction period which afforded an opportunity for the polymer to swell combined with a high CO2 density and extraction temperature above the glass transition (Tg) yielded quantitative recoveries of the additives. Triplicate extractions of the various polystyrene formulations matched additive recoveries obtained by the traditional dissolution/precipitation method. / Master of Science

Tong Hoi Yee. / "July, 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 237-253). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Thesis (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: In this study the deoiling and fractionation of paraffin wax using supercritical fluid extraction (SCFE) has been investigated. SCFE was compared with state-of-the-art processes such as wax crystallisation, static crystallisation and short path distillation. Ethane and carbon dioxide were investigated as supercritical solvents for the supercritical fluid extraction of paraffin wax. Supercritical phase equilibrium data for ethane - n-alkane and CO2 - n-alkane systems close to the mixture critical region were obtained from the literature, and were correlated with several equations of state. Statistical mechanical equations of state failed to correlate the data close to the mixture critical region due to the neglect of density fluctuations which influences phase behaviour close to critical points, or due to inadequate mixing rules. It was found that simple cubic equations of state such as Soave-Redlich-Kwong, Peng-Robinson and Patel-Teja could correlate the data using two interaction parameters. This can be attributed more to their flexibility as correlating tools than to their fundamental accuracy. The Patel-Teja EOS was modified by fitting it to predict low vapour pressure data for long-chain n-alkanes. This modified Patel-Teja EOS was then fitted to the phase equilibria by adjusting two interaction parameters per binary system. The interaction parameters for each solvent (ethane or CO2) system were then fitted to generalised correlations to enable extrapolation to solvent - n-alkane systems for which no equilibrium data were available. The Simplified Perturbed Hardchain theory (SPHC) equation of state was used to correlate lower-pressure solubility data used to model the extract separator. A pilot plant SCFE unit was constructed and used to obtain experimental fractionation data of a low-molecular weight Fischer-Tropsch wax. The experimental results indicate that fractionation of the wax is possible and that the separation efficiency is enhanced by returning some of the extract to the column as reflux. An equilibrium stage model was constructed and used to simulate the extraction experiments. It was possible to obtain good agreement between the experimental results and model predictions. Deoiling of petroleum waxes with a low n-paraffin content (which are not currently deoiled commercially) was investigated. Experimental SCFE and SPD results indicated that selective deoiling is not possible, since the separation is based on differences in molecular weight (or vapour pressure). Simulations of wax crystallisation or solvent extraction and practical tests indicate that deoiling is possible, based on differences in structure and therefore melting point of the components in the wax. Practical problems associated with crystallisation or solvent extraction such as filtration, the use of chlorinated solvents and low yields currently prevent the commercial deoiling of these waxes. During crystallisation of these waxes a soft wax cake is formed which impedes the operation of static crystallisation. A detailed study of the economics of n-paraffin wax deoiling using SCFE was conducted. Flow sheets were proposed to minimise the energy consumption of the SCFE process. Comparison of SPD, static crystallisation and SCFE indicates that a SPD plant will be the cheapest option for deoiling the wax feed investigated. Fractionation of heavier waxes using SPD might not be economically feasible, since the distillation temperature increases dramatically with increasing molecular weight, which leads to higher energy cost. For medium to long chain n-paraffin waxes SCFE should be very competitive, since the capacity of the supercritical solvent can be manipulated to extract longer chain waxes without increasing the extraction temperature. Static crystallisation appears to be the more expensive deoiling option, due primarily to the large initial capital investment cost. / AFRIKAANSE OPSOMMING: Die olieverwydering en fraksionering van paraffienwasse met behulp van superkritiese ekstraksie is in hierdie studie ondersoek. Die modellering van moderne olieverwyderings- en fraksioneringsmetodes soos waskristallisasie, statiese kristallisasie en kortpad distillasie is ook ondersoek. Etaan en koolstofdioksied is ondersoek as superkritiese oplosmiddels vir die superkritiese ekstraksie van paraffienwasse. Literatuurdata van superkritiese fase-ewewigte vir etaan - n-alkaan en CO2 - n-alkaan stelsels naby die mengselkritiese punt is versamel en gekorreleer met verskeie toestandsvergelykings. Statisities-meganiese toestandsvergelykings kon nie data naby mengselkritiese punte korreleer nie, moontlik weens digtheidsvariasies wat afwykings van klassieke gedrag teweegbring, of onakkurate mengreëls. Eenvoudige kubiese toestandsvergelykings soos Soave-Redlich-Kwong, Peng-Robinson en Patel-Teja kon op die ewewigsdata gepas word deur gebruik van twee interaksieparameters. Dit kan eerder toegeskryf word aan hulle buigsaamheid eerder as hulle fundamentele akkuraatheid. Die Patel-Teja toestandsvergelyking is gemodifiseer deur dit te pas op lae dampdruk data van langketting n-alkane. Hierdie gemodifiseerde toestandsvergelyking is gepas op die fase-ewewig data deur twee interaksieparameters te gebruik per binêre sisteem. Die interaksieparameters vir die oplosmiddel stelsels (etaan of CO2) is gekorreleer met algemene vergelykings sodat dit vir ekstrapolasie na oplosmiddel - n-alkaan stelsels gebruik kan word waarvoor ewewigsdata nie beskikbaar is nie. Die "Simplified Perturbed Hardchain" teorie (SPHC) toestandsvergelyking is gebruik om laer druk oplosbaarheidsdata te korreleer vir gebruik in die modellering van die ekstrak skeier. In Superkritiese ekstraksie loodsaanleg is gebou en gebruik om eksperimentele fraksioneringsdata van 'n lae molekulêre massa Fischer- Tropsch was te genereer. Vanaf die eksperimentele resultate blyk fraksionering van was moontlik te wees. Die doeltreffendheid van die skeiding kan verhoog word deur terugvloei van ekstrak na die kolom. 'n Ewewigsmodel is opgestel en gebruik om die ekstraksie eksperimente te modelleer. Deur die ekstraksiedruk en aantal stadia te verander kon goeie ooreenstemming met eksperimentele resultate verkry word. Die verwydering van olie uit petroleumwasse met In lae n-paraffien inhoud (wat nie tans kommersiëel ontolie word nie) is ondersoek. Eksperimentele resultate vir superkritiese ekstraksie en kortpad distillasie dui daarop dat selektiewe olieverwydering nie moontlik is nie, omdat die skeiding gebaseer is op verskille in molekulêre massas en dus (of dampdrukke). Simulasies van waskristallisasie dui op die moontlikheid van olieverwydering gebaseer op verskille in strukture van die komponente in die was. Praktiese probleme geassosieer met kristallisasie of oplosmiddel ekstraksie soos filtrasie, lae opbrengste en gebruik van gechlorineerde koolwaterstowwe as oplosmiddel belemmer die kommersialisering van olieverwydering vir hierdie tipes wasse. 'n Gedetaileerde studie van die ekonomiese lewensvatbaarheid van superkritiese olieverwydering is uitgevoer. Vloeidiagramme is voorgestelom die energieverbruik van die superkritiese ekstraksieproses te minimeer. Vergelyking van kortpad distillasie, statiese kristallisasie en superkritiese ekstraksie dui daarop dat kortpad distillasie die goedkoper opsie vir die olieverwydering van die spesifieke was is. Fraksionering van swaarder wasse met kortpad distillasie sal moontlik nie haalbaar wees nie omdat die distillasietemperatuur drasties toeneem met molekulêre massa. Die skeiding van medium tot langketting wasse met superkritiese ekstraksie behoort meer mededingend te wees, want die kapasiteit van die superkritiese oplosmiddel kan maklik verstel word om langer kettinglengtes wasse te ekstraeer sonder om die temperatuur te verhoog. Statiese kristallisasie blyk die duurder olieverwyderingsopsie te wees hoofsaaklik weens die hoë kapitaalkoste van so 'n aanleg.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Long-chain hydrocarbons are of value to numerous lucrative industries. Due to the low volatility and close melting and boiling points of these solutes, traditional fractionation methods lack the required selectivity for separation and cause thermal degradation of the product. This project investigates the feasibility of Supercritical Fluid Extraction (SFE) for processing these systems, with the primary objective of modelling the high-pressure vapour-liquid equilibrium (VLE) properties of hydrocarbon solutes with a light-weight solvent using a semiempirical equation of state (EOS). Pure component vapour pressures and saturated liquid volumes are also investigated. A thorough investigation into the phase behaviour of the n-alkanes, 1-alcohols, carboxylic acids and esters in light weight supercritical solvents CO2, ethane and propane revealed that the solute structure and temperature largely influence the solute solubility and process feasibility. Good selectivity amongst the various solutes was observed for all three solvents, but very high pressures were required for complete miscibility using CO2 (exceeding 30 MPa). The quadrapole moment of CO2 further leads to complexities in phase behaviour such as temperature and density inversions (CO2/alkanes and CO2/alcohols) and 3-phase regions within the operating range. Simple linear trends in pressure vs. carbon number and temperature were observed for all the considered series using ethane and propane and these solvents were thus selected for conducting the modelling for this study. A thorough review of semi-emperical EOS models from literature revealed that the simple cubic equations of state (CEOSs) provide a promising modelling approach for SFE applications due to their simplicity, flexibility and reliability. The simple Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) EOSs provide good correlation of vapour pressure (%AAD below 5 %) for all the series over a large carbon number range (up to nC20), provided a two parameter alpha function is used. A 3rd parameter in the volume dependence for Patel-Teja (PT) EOS provides considerable improvement over the PR and SRK EOSs for satureate liquid volume correlations of the non-polar solutes (alkanes and esters), but offers virtually no advantage for the more polar alcohols and acids. The CEOSs therefore suffer clear limitations in simultaneous representation of these saturation properties (vapour pressure and liquid molar volume) for the systems of interest. Good correlations of high pressure binary VLE data were obtained using CEOSs available in the Aspen Plus ® simulator (% AAD in P, T and X2 generally below 1 % and ranging from 4 to 12 % for Y2 for all series) provided that two binary interaction parameters (BIPs) are used in the model mixing rules, irrespective of the model used. Aspen Plus ® was further validated as a reliable thermodynamic tool by comparing model fits using the RK-ASPEN model with parameters obtained from the Aspen Plus ® data regression routine and computational methods used in self-developed MATLAB software. Very similar results were obtained for both computational methods, which encourages the use of Aspen Plus ® for process modelling in SFE applications. A statistical sensitivity analysis into the relative effect and interactions between 6 modelling factors in applying the CEOSs revealed that the mixing rules, temperature and solute structure had the largest effect on the correlation of the high pressure VLE, with the pure component limit having negligible effect once BIPs are fitted to data. A significant interaction was, however, observed between the pure component model and the solute structure and temperature, which suggest that accurate correlation of mixture VLE does not solely rely on appropriate mixing rule selection, but also the pure model. Binary interaction parameters (BIPs) in model mixing rules were found to become intercorrelated when more than one are used, greatly impeding the development of generalized correlations. BIPs were also found to be sensitive to the pure component limit (alpha function and pure constants used), the temperature, the combining rules used and possibly the fluid density. These factors should all be taken into account systematically for developing generalized correlations which therefore fell outside the scope of this study. Recommendations were, however, made on how the MATLAB software developed in this study can be used to both expand the size of the statistical analysis already conducted into relevant modelling factors and to develop new generalized correlations for BIPs and new mixing rules. / AFRIKAANSE OPSOMMING: Lang-ketting koolwaterstowwe is van waarde in talle winsgewende industriële toepassings. Vanweë die lae vlugbaarheiden ooreenstemmende kook- en smeltpunte van hierdie molekules, toon tradisionele fraktioneringsmetodes nie die nodige selektiwiteit vir ekstraksie nie en veroorsaak bonop termiese degradering van die produk. Hierdie projek ondersoek dus die lewensvatbaarheid van superkritiese ekstraksie vir die prosesering van hierdie sisteme, met primêre fokus op die modellering van die hoë-druk damp-vloeistof ewewig eienskappe van koolwaterstowwe opgelos in ‘n lae-massa oplosmiddel met gebruik van ‘n semi-empiriese toestandsvergelyking. Suiwer-komponent dampdrukke en versadigde vloeistof volumes word ook ondersoek. ‘n Deeglike ondersoek na die fasegedrag van die n-alkane, 1-alkohole, korboksiel-sure asook esters in lae-massa superkritiese oplosmidds CO2, etaan en propaan toon dat die struktuur van die opgeloste stof en die temperatuur ‘n groot invloed het op die oplosbaarheid en proses lewensvatbaarheid. Goeie selektiwiteit tussen die verskillende koolwaterstowwe was waargeneem vir al drie oplosmiddels, alhoewel baie hoë drukke nodig was vir totale vermenging van die fases in CO2 (hoër as 30 MPa). Die quadrupool moment van CO2 veroorsaak verder ongewenste kompleksiteite in fase gedrag soos temperatuuren digtheid inversies (CO2/alkane en CO2/alkohole) en 3-fase-gebiede in die bedryfs-kondisies. Eenvoudige lineêre tendense in druk tenoor die koolstofnommer van die opgeloste stof asook die temperatuur was waargeneem vir al die ondersoekte koolwaterstof reekse in etaan en propaan en hierdie oplosmiddels was dus gekies vir die modellering vir hierdie studie. 'n Deeglike oorsig van semi-empiriese toestandsvergelykings uit die literatuur het getoon dat die eenvoudige kubiese toestandsvergelykings ‘n belowende modelleringsbenadering bied vir superkritiese ekstraksie toepassings vanweë hul eenvoudigeid, buigsaamheid enbetroubaarheid. Die eenvoudige Peng-Robinson (PR) en Soave-Redlich-Kwong (SRK) toestandsvergelykings bied goeie korrelasie van suiwer dampdruk (foute laer as 5 %) vir alle koolwaterstowwe oor ‘n groot koolstofnommer gebied (tot by nC20), met die voorwaarde dat ‘n 2 parameter alpha funksie gebruik word. ‘n 3rde parameter in die volume afhanklikheid van die Patel-Teja (PT) toestandsvergelyking bied ‘n beduidende verbetering in die passing van die versadigde vloeistof volume vir die nie-polêre koolwaterstowwe (n-alkane en die esters), maar bied geen voordeel vir die meer polêre alkohole en karkoksiel sure nie. Die kubiese modelle toon dus duidelike beperkings vir die gelyktydige voorstelling van hierdie versadigingde eienskappe (dampdruk en vloeistof volume) vir die sisteme van belang. Goeie korrelasie van hoë druk binêre damp-vloeistof ewewig data was verkry deur gebruik van die kubiese toestandsvergelykings beskikbaar inAspen Plus ® (fout in P, T en X2 tipies laer as 1 % en van 4 tot 12 % vir Y2 vir alle sisteme), met die voorwaarde dat 2 binêre interaksie parameters gebuik word in die model mengreëls, onafhanklik van die model. Aspen Plus ® was verder bekraktig as ‘n betroubare termodinamiese hulpmiddel deur model passings te vergelyk met die RK-ASPEN model tussen gevalle waar parameters verkry is deur die beskikbare regressie metode in Aspen Plus ® en metodes gebruik in self-ontwikkelde MATLAB sagteware. Eenderse resultate was verkry vir beide berekeningsmetodes, wat die gebruik van Aspen Plus ® vir prosesmodellering in superkritiese ekstrasie toepassings aanmoedig. ‘n Satistiese sensitiwiteits analise op die relatiewe effek en interaksies tussen 6 modelleringsfaktore in die toepassing van die kubiese toestandsvergelykings het gevind dat die mengreëls, temperatuur en die stuktuur van die opgeloste stof die grootste effek op die korrelasie van hoë druk binêre damp-vloeistof ewewig het, met ‘n weglaatbare effek vandie suiwerkomponent limiet waargeneem sodra binêre interaksie parameters gepas is aan data. ‘n Beduidende interaksie was wel waargeneem tussen die suiwerkomponent model en die struktuur van die opgeloste stof asook die temperatuur, wat daarop dui dat akurate korrelasie van mengsel damp-vloeistof ewewig nie slegs afhanklink is van ‘n gepaste keuse van mengreëls nie, maar ook die suiwer-komponent model. Binêre interaksie parameters in die model mengreëls ondergaan inter-korrelasie wanneer meer as een interaksie parameter gebruik word, wat die ontwikkeling van algemeen toepaslike korrelasies grotendeels belemmer. Binêre interaksie parameters was ook bevind om sensitief te wees tot die suiwer component limiet (alpha funksie en suiwer konstantes wat gebruik is), die temperatuur, die kombineringsreëls en moontlik die vloeistof digtheid. Hierdie faktore moet dus almal sistematies in ag geneem word wanneer algemeen toepaslike korrelasies ontwikkel word, wat dus buite die omvang van die huidge studie val. Aanbevelings was wel gemaak vir hoe die MATLAB sagteware ontwikkel vir hierdie studie gebruik kan word om beide die betaande statistiese analise uit te brei, asook nuwe korrelasies vir binêre interaksies parameters en nuwe mengreëls te ontwikkel.

No description available.