Controlling molecular weight cut-off of PEEK nanofiltration membranes using a drying method

Abstract

Cite this article as: João da Silva Burgal, Ludmila Peeva, Patrizia Marchetti and Andrew Livingston, Controlling molecular weight cut-off of PEEK nanofiltration membranes using a drying method, Journal of Membrane Science, http://dx. KEYWORDSPoly(ether ether ketone); Organic solvent nanofiltration; drying method; control of molecular weight cut-off; statistical analysis. 2 3 ABSTRACT In this research paper we report two ways of controlling the molecular weight cut-off (MWCO) of PEEK membranes prepared via phase inversion and subsequent drying. The two methods explored were the change of polymer concentration in the dope solution -8 wt.%, 10 wt. % and 12 wt. % -and the variation of solvent filling the pores prior to drying -e.g.water, methanol, acetone, tetrahydrofuran and n-heptane. The results show that it is possible to vary the MWCO from 295 g.mol -1 to 1400 g.mol -1 by varying these parameters. A statistical analysis based on a genetic algorithm showed that the Hansen solubility parameter, polarity and their interactions with molar volume were likely to be the most important parameters influencing the performance of PEEK membranes when drying from different solvents. In addition, the drying temperature also proved to have an effect on the membrane performance -the higher the temperature the higher the rejection and the lower the permeance. IntroductionOrganic Solvent Nanofiltration (OSN) membranes can be used for separation in the chemical and pharmaceutical industry to perform concentration and purification and solvent recovery. Recently, it was shown how OSN could be used for catalytic reactions with reaction and separation occurring in situ under high temperature and basic conditions [1].One of the main challenges of fabricating suitable OSN membranes is to have the right MWCO to perform the separation of interest. The most widely used method for manufacturing polymeric membranes is the phase inversion method. This method involves four mains steps: dissolving a polymer in an appropriate solvent (dope solution); membrane casting; phase inversion (wet or dry); and membrane post-treatment [2].It is known that it is possible to manipulate the membrane performance by varying the composition of the dope solution, varying the conditions during the phase inversion step or via a post-treatment step (drying, conditioning or crosslinking) [3,4]. 4In the dope preparation step it is necessary to take into account the polymer concentration, the addition of volatile solvents, non-solvents (or "bad" solvents) and pore forming additives [4]. It has been observed that polymer concentration has a significant effect on the viscosity which in turn affects the performance of the final membrane (higher concentration leads to higher selectivity but lower permeance) [5]. Volatile solvents such as ethylether (EE), tetrahydrofuran (THF) or dioxane, could be added to the dope solution in order to produce integrally skinned asymmetric membranes via the dry/wet method (where the evaporation step is essential) [6,7]. By allowing partial...

Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving

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Polyelectrolyte complex nanofiltration membranes by surface deposition of polyethylenimine on polyanion supports

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Thin-Film Composite Nanofiltration Membranes for Non-Polar Solvents

“…To prepare the porous support membrane, various materials have been commonly used such as polysulfone (PSF) [ 14 , 15 , 16 , 17 , 18 , 19 ], polyethersulfone (PES) [ 20 , 21 ], poly(ether ether ketone) (PEEK) [ 22 , 23 , 24 ], polyacrylonitrile (PAN) [ 25 , 26 ], poly(vinylidene fluoride) (PVDF) [ 27 , 28 , 29 ], polyethylene (PE) [ 30 ], polypropylene (PP) [ 31 , 32 , 33 ], the recycled polyethylene terephthalate (PET) [ 34 ], and cellulose [ 35 ] as shown in Table 1 . Most of the porous support membranes are prepared by the phase inversion method, while the common polyolefin membranes including PE and PP are manufactured by sequential steps consisting of the melt extrusion and mechanical stretching [ 36 ].…”