No abstract

No abstract

No abstract

No abstract

Pharmaceutical production typically involves multiple reaction steps with separations between successive reactions. Two processes which complicate the transition from batch to continuous operation in multistep synthesis are solvent exchange (especially high‐boiling‐ to low‐boiling‐point solvent), and catalyst separation. Demonstrated here is membrane separation as an enabling platform for undertaking these processes during continuous operation. Two consecutive reactions are performed in different solvents, with catalyst separation and inter‐reaction solvent exchange achieved by continuous flow membrane units. A Heck coupling reaction is performed in N,N‐dimethylformamide (DMF) in a continuous membrane reactor which retains the catalyst. The Heck reaction product undergoes solvent exchange in a counter‐current membrane system where DMF is continuously replaced by ethanol. After exchange the product dissolved in ethanol passes through a column packed with an iron catalyst, and undergoes reduction (>99 % yield).

Pharmaceutical production typically involves multiple reaction steps with separations between successive reactions.T wo processes which complicate the transition from batch to continuous operation in multistep synthesis are solvent exchange (especially high-boiling-to low-boiling-point solvent), and catalyst separation. Demonstrated here is membrane separation as an enabling platform for undertaking these processes during continuous operation. Tw oc onsecutive reactions are performed in different solvents,w ith catalyst separation and inter-reaction solvent exchange achieved by continuous flowmembrane units.AHeck coupling reaction is performed in N,N-dimethylformamide (DMF) in acontinuous membrane reactor which retains the catalyst. The Heck reaction product undergoes solvent exchange in ac ountercurrent membrane system where DMF is continuously replaced by ethanol. After exchange the product dissolved in ethanol passes through acolumn packed with an iron catalyst, and undergoes reduction (> 99 %y ield).

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...

In this work it is shown that PEEK membranes are “green” from the production point of view when compared with commercial polyimide (PI) based organic solvent nanofiltration (OSN) membranes.