status and perspectives of organophilic …dortmund / germany, phone +49 (0) 231-730696 tab. 1:...

1. Introduction

A big potential attributed to organo -philic nanofiltration with separation limitsin the range from about 150 to 1000, is toovercome the previous limits of separabil-ity of substance mixtures, to regenerateand clean solvents, as well as to carefullyextract temperature-sensitive recyc lables.A number of industrial processes werealready able to be implemented during thelast few years. The basis for them isformed by a range of commercially avail-able membranes and module configura-tions. However, in contrast to many appli-cations with aqueous substance systems,OSN systems are never to be looked at asturnkey systems. This, above all, wasemphasized by Youri Bouwhius, AndrewBoam and Axel Kobus of EvonikIndustries AG in their introductory lecture.Differently from the water market, it isimpossible to act simply as a supplier forOEMs without having contact with endcustomers oneself. Rather, the enterprisegets involved itself in the development of asolution for special separation tasks. Thisis also important in the respect thatorganophilic nanofiltration is not justreplacing another mostly thermal separa-tion process, but often also means a newprocess procedure and/or obtaining newproducts. Up to now, 32 different applica-tions for OSN have thus been identifiedand of these, 20 have been judged as com-mercially viable. At the time of the lecture,three of these were in the technical stage,eight in the laboratory or pilot phase andthe remaining nine were being looked at ascase studies. To persuade an end customerof the advantages of a process transforma-tion, or the production of a new product, aswell as also to implement this, then

46 F & S International Edition No. 14/2014

Highlights 2013

Status and perspectives oforganophilic nanofiltration H. Lyko*

Separation processes in the chemical and pharmaceutical industry make up a high proportion of plant and operatingcosts for production processes; this is true for water-based substance systems, as well as for those that are based onorganic solvents. While membrane technology is established for aqueous substance mixtures and its advantages areindisputable compared with thermal separation processes, particularly with respect to energy consumption and spacerequirements, membranes and membrane separation processes in conjunction with organic solvents are often still in anearly stage of market development. Especially interesting for a large number of separation tasks, that up to now canonly be handled thermally, is the nanofiltration of organic solvents. At the 4th International Conference on OrganicSolvent Nanofiltration (OSN) /1/, that was held in March 2013 by the Department of Chemical Process Engineering(Aachener Verfahrenstechnik) and the DWI (German Wool Research Institute, now the Institute for the Development of“interactive” materials) of the Aachen RWTH under the direction of Prof. Matthias Wessling, about 60 participantsdiscussed the newest results from research and development, as well as experiences with industrial processes of OSN.In the course of this, it seems that all research institutes in Europe specializing in this area were represented, as well asscientists from Russia, Asia and the USA, and also industrial enterprises active in this sector.

*Dr.-Ing. Hildegard LykoDortmund / Germany, Phone +49 (0) 231-730696

Tab. 1: Overview of different membrane polymers that are suitable for OSN (Basic structures,partly still cross-linked by specific molecules at the time of membrane production)

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requires time and also a different business model than that of beinga pure component supplier. Therefore, the benefit from the intro-duction of OSN, on one hand through saving energy and materialcompared with thermal processes, and on the other hand asincreased added value through possibly better products, shouldalso be reflected in attainable prices for the membranes and mod-ules.

Besides the development, production and characterisation ofnew membrane materials and the realisation of new processes,many presentations were on the agenda in this conference that alsodealt with methods of advance calculation of separation efficien-cies, membrane selection and process design.

2. Membrane materials and their properties

The number of solvent-stable membrane materials available sofar in industrial orders of magnitude is relatively limited. Indeed,in addition, various substance classes or modifications were stillpresented that, up to now, were manufactured and characterized ona laboratory scale and have been tested in filtration tests. Somepolymers form the basis of the most important membrane develop-ments for OSN, which, as an overview, are shown in Table 1 intheir basic structure, most notably polyimides and polydimethyl-siloxane (PDMS). Thus, the products by Evonik, Duramem andPuramem, which were also described several times at this event,consist of such polymers. Duramem is an ASN (asymmetric inte-grally skinned) membrane made from polyimide. Puramem is acomposite membrane with a silicone layer. The Borsig group, too,to which GMT Membrantechnik GmbH belongs, uses silicone-based composite membranes for organophilic nanofiltration.Katrin Ebert showed this in her report on the activities of GMT inthis area. However, in her explanation, module selection alsoplayed an important role. Spiral wound modules and pocket mod-ules are being used. On the question of a performance and costcomparison of the two types of module, the pocket module wasshown to be the more expensive one, but possibly better suited forhigher flow rates.

Vitreous polyetheretherketone (PEEK) is also considered to beespecially chemically stable. Gas separation and fuel cell mem-branes are also made from this. Katrien Hendrix of the Centre forSurface Chemistry and Catalysis at KU Leuven has producedmembranes from polymers of this construction type and has char-acterised them. Here, the standard polymer, which is produced bypolycondensation of difluorobenzophenone and hydroquinone,was modified to make it soluble for the manufacturing process ofOSN membranes. Thus, the monomer hydroquinone was replacedby another one from the group of diphenones. The molecule illus-trated in Table 1 contains tertiary butylhydroquinone. With the

generated PEEK variations, with different solvent compositions forthe drawing solution, and with different crosslinkers and otherparameters of phase inversion, membranes were produced andcharacterised with different methods. Inter alia, a clear influenceof the solvent combination on the thickness of the separation-active layer, the permeability and the retention of the test substancerose bengal (a dye) was found.

Polymers with intrinsic microporosity have solid molecularscaffolds, whose interstices can be changed neither by mechanicalcompression during filtration, nor by temperature influences. Oneexample of this is the polymer shown in Table 1, PIM-1 (PIMstands for: polymer of intrinsic microporosity), with which

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F & S International Edition No. 14/2014 47

Fig. 1: Hybrid NF membrane for organophilic nanofiltration - ceramiccoating (approx. 200 nm) on a robust supporting structure made ofpolymer (image: ECN, SolSep BV, HybPON-Konsortium NL)

Fig. 2: Test cell for performing spectroscopic ellipsometry underfiltration conditions (image: Twente University see /7/)


Patricia Gorgojo et al., from ImperialCollege in London, experimented. Theessential advantage of intrinsic microp-orosity (in accordance with IUPAC, poresless than 2 nm are understood by this)exists in the clearly increased permeabilityin comparison with customary TFC mem-branes. Extraordinary stability in organicsolvents, as well as in highly corrosiveenvironments, is also displayed by Poly -benzi midazole. This type of membraneswas also made and tested in ImperialCollege under the direction of Prof.Andrew Livingston and a patent wasapplied for /5/.

Silsesquioxanes (Organosilicates) unitethe stability of silicates with the flexibilityof rubbery polymer. Toshinori Tsuru et al.from Hiroshima University make mem-branes from materials that can be repre-sented by the sum formula RSiO3/2. Thetype and length of hydrocarbons hidingbehind the abbreviation “R” cause theflexibility / strength of the originatingstructures. If alkanes are used, onereceives flexible, dense membranes; wheninserting aromatic compounds, rigidporous structures originate. One materialtype from this group, from which oneexpects superior properties, are so-calledpolyhedral oligomeric silsesquioxanes(POSS, see Table 1). How to produceultrathin POSS-polyamide films fromthese building blocks is described in thethesis of M. Dalwani from Twente /4/. InAachen, Yali Zhang, University ofTechnology of Twente, presented aprocess in which these films are imple-mented in situ in microchannels. They aresupposed to be used for solvent exchangein microfluidic systems. In the course ofthis, the selectivity of these membranes isnot as important as their permeability andtheir mechanical stability, since the sol-vent exchange takes place via a displace-ment process.

The Dutch company SolSep BV, underthe trade name HybSi®, produces pervapo-ration membranes which consist of amicroporous layer on a ceramic substrate(as capillaries). For OSN, ManagingDirector Peter Cuperus presented a newconcept for hybrid membranes made froma polymer substrate with an approx. 200nm thick ceramic coating (see Fig. 1),which also allows for the production offlat sheet membranes and with it for theassembly to spiral-wound modules.

With purely ceramic membranes theapplication limits still to be overcome liein the achievable separation limit and inthe hydrophilicity of the ceramics, so thatthey must be modified for sufficient wet-ting with organic solvents. As Ingolf Voigtof the Fraunhofer Institute for CeramicTechnologies and Systems (IKTS) demon-strated, commercial ceramic membraneswith separation limits of 450 have beenavailable there for ten years. Hydro -phobiza tion of the ceramics is achieved bymodification with silanes. However, theirmolecular dimensions are so large that onedoes not take nanofiltration membranes asa starting material, but instead one takesultra-filtration membranes in order toallow sufficient penetration of the silanes.The lower separation limit of a silanisedUF membrane is approximately 600 Da.More recent developments within thescope of the nano-membrane project, inwhich, inter alia, the Merck chemicalscompany is also involved, aim at the pro-duction of ceramics by means of Sol-gelprocesses and in situ hydrophobicisation.The new membranes have a substructuremade from TiO2, an intermediate layermade from ZrO2 as well as a separation-active layer made from both oxides. Theproduction is done using complex-formingagents, which support gelation and alsohave an influence on the freedom from

defects and therefore also on the real sep-aration limit. Membranes were producedwhich, in aqueous solutions, presentedMWCOs of 200 - 300 Da, and the cut-offof the finest membrane in organic solventswas approx. 350 Da. The recoverableretention of organic substances dependedstrongly on the solvent used.

As a special, also mechanically verystable class of membranes, Santanu Karan(Imperial college of London UK)described diamond-like, ultra thin hydro-carbon layers (10 - 40 nm, called DLClayers (diamond-like carbon)) on porousceramics, which allow a high, viscosity-dependent flow of organic solvents withconcurrent retention of dissolved organicmolecules (for details see /6/). The ultra-thin layer is applied by plasma depositionof a vaporous hydrocarbon, diluted with aninert gas. Here, not a pure carbon skeletonis formed, but a self-supporting amor-phous layer of very regular and highlycross-linked organic structures with a highcarbon content, between which there arehydrophobic nanopores with a total poros-ity of about 12%. Before the plasma depo-sition of the hydrocarbon, the substrate iscovered with an approx. 80 nm thin layermade of cadmium hydroxide nanofibres,which is subsequently dissolved again,using an ethanolic solution of hydrochloricacid. So that the nanofibres are not dam-aged during the plasma coating, the coat-ing takes place at a temperature of -20°C.

3. New method of membraneproduction

A large part of the membranes used forOSN are thin-film composite membranesin which the separation-active layer isdeposited on a porous substructure, forexample a UF membrane. A commonprocess for applying the separation-activelayer is interfacial polymerisation. For

Fig. 3, a: Isolines of permeability for three different solvents, a so-calledMembrane Permeability Map (MPM) for commercial OSN membraneStarmem 122 (image: University of Technology of Dortmund,Department of Biochemical and Chemical Engineering, Institute ofFluid Process Engineering)

Fig. 3, b: Isolines for the retention of Phenyldodecane in a ternarysolvent mixture (Membrane Rejection Map (MRM)) by the OSNmembrane Starmem 122 (image: University of Technology ofDortmund, Department of Biochemical and Chemical Engineering,Institute of Fluid Process Engineering)


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this, the substrate is saturated with an aqueous solution of themonomer concerned (possibly after pretreatment for the improve-ment of wettability), and afterwards the system is immersed in theorganic solution containing the second reactant of the polymerisa-tion. At the interface of the two immiscible solvents, the twomonomers meet with each other and polymerise in a very thinlayer. For this production process, simpler and faster alternativesare sought. For instance, Elke Dom of the Catholic University ofLeuven in Belgium suggested combining the production of the UFmembrane used as a substrate with the first step of the wetting withthe aqueous solution. In the examined case, the last step of themanufacture of a UF membrane was carried out by phase inversionwith an aqueous solution, which at the same time already con-tained the monomer for interfacial polymerisation. Besides thesaving of a production step, one expects from this method also aneasier and more complete impregnation of the substructure withthe monomer, because it is precisely already present in the coagu-lation bath. If the substructure consists of solvent-stable, cross-linked polyimide, then the crosslinkers are identical for the sub-structure and interfacial polymerisation.

4. Characterisation of membrane materials

One of the most important interactions between solvent andpolymer membranes that affect the separation behaviour is theswelling behaviour, i.e. the absorption of solvent by the membranematerial. The more fluid the membrane absorbs, the more flexibleit will become and with this, stability, permeability and retentioncapacity change. The swelling behaviour also depends therefore onthe membrane thickness. Nieck Benes, University of Twente,demonstrated in his Keynote Speech how this behaviour isanalysed with the help of spectroscopic ellipsometry. With spectralellipsometry, thickness, refractive index and surface roughness ofthin layers of material can be measured in a contactless manner. Inthe present case, this measurement method was applied in a specialtest cell under filtration conditions, i.e. under increased pressurewith permeation through the membrane. The course of the thick-ness across temperature and hence the glass transition temperatureof the polymer used can be determined by heating the film to beexamined. Through the course of the change in thickness in thepresence of various solvents, through the time and depending onthe pressure, mechanisms of transport through the examined mem-brane are illustrated. An exact description of the method and theresults obtained with the permeation of n-hexane by means of dif-ferently cross-linked PDMS films is provided in /7/.

The sorption capacity of membranes is also measured usinggravimetric steam sorption measurements or by gas chromatogra-phy. The latter means the exposure of the material to a test gas mix-ture and the analysis of the transmitted components with a flameionisation detector. Thomas Schmid, as a representative of theMeasurement Systems manufacturer Surface MeasurementSystems Inc, presented measurements on a poster that had alreadybeen carried out with different membranes.

One can determine the essential features of membrane perme-ability and selectivity only in filtration tests. Here, there is theendeavour to achieve a general comparability of materials. PatriziaMarchetti et al., from Imperial College in London, inter alia askedthe question about the feasibility of a “Robeson plot” for OSNmembranes. The original Robeson plot illustrates the selectivity ofgas separation membranes in mixtures of two gases depending onthe permeability of the faster permeating gas /8/ and has an obvi-ous upper limit of the achievable performance numbers. For OSNmembranes, a reasonable number of common solvents and solutessuch as polystyrene, linear and aromatic alkanes, as well as dyes,were suggested, as well as possibilities for a uniform mode of rep-resentation. Analogous to the representation of gas separation

membranes, the application of selectivity (solvent compared withsolute) over the permeability is an option for the solvent. In thisrepresentation, one can put either different solvents, differentsolutes or different membranes in a diagram and compare them.

5. Membrane selection, modelling of the separationperformance and process design

Because of the huge number of different solvents and the com-plexity of the interaction between solvents and membranes, thepre-calculation of typical data on process design is difficult. Thus,methods are investigated in different projects with which, on thebasis of a limited number of measured values, one can make state-ments about expected separation performance. In TU Dortmund,together with the chemicals company Merck, a study on membraneselection was carried out by means of heuristic methods. AsStefanie Zeidler explained, series of measurements involvingselected solvents and solutes were carried out, which were sup-posed to be sufficiently representative that one can judge the suit-ability of OSN for a separation task problem to be solved, givenknowledge of easily accessible parameters of the substancesinvolved.

As a graphic means for the assessment of permeability and theretention capacity of membranes, Patrick Schmidt et al. (also TUDortmund) created ternary diagrams. The graphics illustrationshown in Figures 3 a and b, which depict the results of measure-ments on the commercial membrane Starmem™122, illustrate aclear dependence of the retention of the dissolved component onthe composition of the solvent mixture. With the help of the iso-lines, which can also be represented as selectivities (Membrane

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Selectivity Maps, MSM, not shown here),one can select the solvent compositionsuitable for a desired filtration result (seealso /9/).

Patrizia Marchetti ventured to take onthe forecast of permeability for differentsolvents by means of OSN membraneswith the help of a relatively simple model.Thus the viscosity is identified as animportant parameter of the solvents used.According to the Hagen Poiseuille modelfor a viscous pore flow, there is propor-tionality between the permeability and theinverse of the viscosity. Miscellaneouscorrelation factors dependent on the poresize consider surface effects in thenanopores, and the source behaviour offlexible polymer membranes is taken intoaccount through the Hansen solubilityparameters (parameters calculated fromthe energy densities of the different inter-molecular interactions). Other membrane-specific model parameters were deter-mined by permeability measurementswith from four to five different solvents ineach case. With the developed model, cor-respondence could be received successful-

ly between measured and calculated flowrates through ceramic as well as throughpolymer membranes. The permeationbehaviour of solvents through ceramicmembranes is described by AnitaBueckenhoudt of VITO, Belgium, by aphenomenological model. Here, the flowrate of an organic solvent through themembrane, its viscosity as well as theoverall Hansen solubility parameter arebrought into context with the correspond-ing data for the solvent water, namely withthe interposition of a membrane-specificparameter that depends on pore size andthe hydrophilicity / hydrophobicity of themembrane. With this phenomenologicalmodel, one should be able to calculate theflow rate of any solvent or mixture througha membrane if the substance data and thepermeability for water are known.

Dimitar Peshev of Imperial CollegeLondon presented his simulation tool“OSN Designer” with which the perfor-mance of a membrane system can be sim-ulated by using commercial simulationprograms like Aspen One, MATLAB andCAPE OPEN. To achieve this, existing

transport models (solution permeabilitymodel, pore flow model or another phe-nomenological model that describes thepermeation and the retention by the mem-brane), as well as models for the processprocedure (batch operation, semi-batchdiafiltration, stationary continuous filtra-tion) had to be integrated in the simulationsurroundings. As an application example,the concentration of rosemary essence inethanol was named among other things/10/. Here the total energy consumption ofa membrane system could be determinedas a function of reconcentration and com-pared with respective values for distilla-tion in order to assess which processing ismore economical with what concentration.

6. Phenomenon negativeretention

Stefanie Postel, RWTH Aachen,showed that the retention of dissolvedcomponents by a certain OSN membranedepends on the affinity of the solute, onone hand relative to the membrane, butalso relative to the solvent (mixture) used.In certain cases, it comes even to negativeretention of solutes. This was proved withthe help of the three solvents toluene,methanol and isopropanol with differentsolutes to be retained. Therefore, negativeretention can appear if the solubility of acomponent in a solvent is especially high.Here, negative retention of carboxylic acidin methanol and of n-alkanes in methanoland isopropanol were measured. The tech-nical usability of this phenomenon wasdiscussed, but also the objection wasbrought forth that, in such a case, classicalextraction is the more suitable separationprocess.

7. New processes and productswith OSN

The development of hybrid membranesat SolSep described in section 2 happenedwithin the scope of the EU projectSOLVER (Solvent Purification andRecycling in the Process Industry UsingInnovative Membrane Technology) withthe objective to clean solvent streams ofvarious industries and return them torespective processes. As project coordina-tor Peter Vandezande, of the Belgianresearch institute VITO, presented, about85-90% of material consumption in theproduction of a pharmaceutical activeingredient is attributable to a solvent. Forthe electronics industries, the market vol-ume lies at about 2 billion €/a for the sol-vent requirement. Here alcohols are usedmainly for cleaning and conditioning ofcomponents, whose content in metals afterthe treatment must be below 10 ppb.


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Fig. 4: Test facility for the characterisation of OSN membranes (by courtesy of SIMA-tec GmbH,Hürth)

Fig. 5: Process diagram for hydroformylation with micellar systems, followed by an OSN forpurifying the organic phase (image: Department of Process and Chemical Engineering of theUniversity of Technology of Berlin)


Meanwhile flat sheet membranes weretested on different scales and the retentionof a total of about 35 metals from alcoholswas determined. A pilot plant for 4” spiralwound modules or for ceramic modulesallows nanofiltration with up to 45 barpressure at a maximum of 50°C. Withoptimum setting of the operating parame-ters, as high degrees of purity of the sol-vents could be achieved as are required inthe electronic industry.

Ionic liquids, which are used for extrac-tion of recyclables from biomass, also playa special role in the area of solvent recy-cling. Olli Nakari of the University ofTechnology in Lappeenranta, Finland,examined retention of hemicellulose fromionic liquid [EMIM]Oac (1-ethyl-3-methyl-imidazol-acetate). Because theseliquids do not behave like organic sol-vents, no organophilic membranes areactually necessary. However, in practiceone often mixes the liquids with organicsolvents (e.g. methanol) in order to reducethe viscosity and achieve satisfactory flowrates through the membrane withoutincreasing temperature.

Thomas Fahrenwaldt of the Institute ofChemistry of Rostock University is inves-tigating OSN as an alternative to chro-matography for the retention of smallorganic molecules, like different aminoacids, urea derivatives or alkaloids, which,as catalysts, support enantio-selectivereactions. As an example reaction for thepreparation of such an organic catalyst, thederivatisation of quinine with the chloridesof various organic acids was implemented.The chlorides were dosed in excess, toensure a complete reaction and, therefore,were still present as residues in the productsolution. For the purification of the targetproduct with simultaneous removal of theimpurities, a multi-stage diafiltration withethanol was tested. After 5 diafiltrationcycles, a much purer product was receivedthan with chromatography.

In the Department of Process andChemical Engineering of TU Berlin, incooperation with the Department of LifeScience Engineering of Berlin Universityof Technology and Economics, one alsodeals with the extraction of base materialsfrom renewable raw materials. In the cat-alytic conversion of long-chain olefinsfrom renewable raw materials, these aremixed with the help of surfactants with theaqueous phase containing the catalyst.After the reaction, there is still a lesserportion of the surfactant in the organicproduct solution. Daniel Zedel showedthat with the help of the surfactantMarlipal 24/70 in Dodekan, this can beremoved with the help of OSN. However,

it has been established in long-term exper-iments that both permeability as well assurfactant retention decreased with time.

The possibilities to simplify the produc-tion of peptides in the liquid phase withthe aid of OSN, and render it more eco-nomical, are investigated by WenquianChen et al. from Imperial College,London, in cooperation with SchweizerLonza AG. The peptides, which are in highdemand in the pharmaceuticals marketwith huge growth rates, are “tailor-made”from individual amino acids in the con-ventional production process in recurringreaction steps. Between the reaction steps,the excess amino acid must be separated,something that happens up to now byextraction and precipitation. Diafiltrationwith organophilic nanofiltration mem-branes should serve as a substitute forthese complex separation processes. Thefeasibility has been demonstrated, but therequirements for the chemical resistanceof the membranes are very high for thisprocess. Therefore, one works currentlywith ceramic membranes.

Literature:/1/ VIVTA e.V. (Hrsg.): 4th International Conference on

Organic Solvent Nanofiltration, 12. – 14.03.2013,Aachen, Book of Abstracts

/2/ Dutczak, S.M.; Tanardi, C.R.; Kopéc, K.K., Wessling, M.;Stamatialis, D.: “Chemistry in a spinneret” to fabricatehollow fibre for organic solvent filtration; Separation andPurification Technology 86(2012), pp. 183 – 189

/3/ Volkov, A.V.; Parashchuk, V.V. Stamatialis, D.F.;Khotimsky, V.S.: High permeable PTMSP/PAN compositemembranes for solvent nanofiltration; Journal ofMembrane Science 333(2009), pp. 88-93; DOI:10.1016/j.memsci.2009.01.050

/4/ Dalwani, M.: Thin film composite nanofiltration mem-branes for extreme conditions; Dissertation, TwenteUniversity, 2011, ISBN: 978-90-365-3276-1;DOI:http://dx.doi.org/10.3990/1.9789036532761

/5/ Livingston, A.G.; Bhole, Y.S.: Asymmetric membranesfor use in nanofiltration; WO 2012/010886 A1, 2012

/6/ Karan, S.; Samitsu, S.; Peng, X.; Kurashima, K.;Ichinose, I.: Ultrafast viscous permeation of organic sol-vents through diamont-like carbon nanosheets; ScienceVol 335(2012), S. 444-447. DOI: 10.1126/sci-ence.1212101

/7/ Ogielo, W.; van der Werf, H.; Tempelmann, K.;Wormeester, H.; Wessling, M.; Nijmeier, A.; benes, N.E.:n-Hexane induced swelling of thin PDMS films undernon-quilibrium nanofiltration conditions, resolved byspectroscopic ellipsometry; Journal of MembraneScience 437 (2013), pp. 313-323. DOI:10.1016/j.memsci.2013.04.039

/8/ Robeson, L.M.: The upper bound revisited, Journal ofMembrane Science 320 (2008) No. 1-2, pp. 390 -400.DOI 10.1016/j.memsci.2008.04.030

/9/ Schmidt, P.; Köse, T.; Lutze, P.: Characterisation oforganic solvent nanofiltration membranes in multi-com-ponent mixtures: Membrane rejection maps and mem-brane selectivity maps for conceptual process design,Journal of Membrane Science, 429 (2013), 103-120.DOI: 10.1016/j.memsci.2012.11.031

/10/ Peshev, D., Peeva, L.G.; Peev, G.; Baptista, I.I.R.,Boam, A.T.: Application of organic solvent nanofiltrationfor concentration of antioxidant extracts of rosemary(Rosmarinus officiallis L.); Chemical EngineeringResearch and Design 89 (2011) no. 3, 318-327. DOI:10.1016/j.cherd.2010.07.002

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status and perspectives of organophilic …dortmund / germany, phone +49 (0) 231-730696 tab. 1:...

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