## 4 Conclusions  
In this work the effect of long-term contact with real ABE-fermutation broth of composite membranes made of PDecMS and PHeptMS, as well as the commercial membrane MDK-3, was studied for the first time. It was shown that for all investigated membranes after one month of contact with broth there was a clogging of the surface of the selective layer. Based on the data of elemental analysis and infrared spectroscopy, the protein nature of deposits (microorganisms, products of their life activity) was revealed. For all membranes, a decrease in contact angles for water, n-butanol, acetone, and ethanol was observed after fouling. The smallest change in wetting angles was observed for the PHeptMS membrane.  
A comparison of the transport and separation properties of the membranes before and after a one-month exposure in the broth was studied in the pervaporation separation of the real ABE-fermutation mixture. It was noted that the flux of clogged membranes was lower than that of fresh membranes. The ABE/water separation factors of PDecMS and MDK-3 membranes decreased after clogging, which was due to an increase in the hydrophilicity of the surface of these membranes. The opposite trend was observed for PHeptMS. For all investigated membranes, a decrease in their PSI was observed after fouling as compared to the initial membranes. Nevertheless, the PHeptMS membrane before and after clogging retained the maximum PSI value for n-butanol among the studied membranes. As the temperature of the separated ABE mixture increased, an increase in permeate flux was observed for all membranes. The maximum values of the organic component/water separation factor were observed for the PHeptMS membrane--74 for butanol, 61 for acetone, and 10 for ethanol at 60 \({}^{\circ}\)C.  
For the most selective PHeptMS membrane, the dynamics of its contamination during vacuum pervaporation of real ABE-fermutation broth for 216 h were investigated. During the first 28 h of the experiment, the partial fluxes of the mixture components decreased. Subsequent stabilization of water, n-butanol, and ethanol fluxes, as well as some increase in acetone flux, indicate contamination of the selective layer surface. For the next \(\sim\)100 h, the performance of the composite membrane was stable and exhibited an average total flux of 0.16 kg/(m\({}^{2}\)-h) and average separation factors of 49.5, 44.8, and 6.3 for acetone, butanol, and ethanol, respectively. After 150 h of contact with the fermentation mixture, a 10% decrease in the selectivity of PHeptMS for all components was observed due to an increase in water permeability through the membrane. The overall decrease in the total flux during separation of the ABE-fermutation mixture by a factor of 1.28 indicates the necessity of its modification to increase its stability during long-term contact with the fermentation mixture.  
Conceptualization, E.A.G. and I.L.B.; Data curation, T.N.R., O.V.A. and G.N.B.; Formal analysis, T.N.R., E.A.G. and O.V.A.; Funding acquisition, G.S.G.; Investigation, T.N.R., E.A.G. and O.V.A.; Methodology, T.N.R., E.A.G., G.N.B., G.S.G. and I.L.B.; Project administration, G.S.G.; Visualization, T.N.R. and A.V.V.; Writing--original draft, T.N.R. and E.A.G.; Writing--review and editing, E.A.G., G.S.G. and A.V.V. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Russian Science Foundation, grant number 22-79-10332, [[https://rscf.ru/project/22-79-10332/](https://rscf.ru/project/22-79-10332/)]([https://rscf.ru/project/22-79-10332/](https://rscf.ru/project/22-79-10332/)) (accessed on 19 February 2023).  
Not applicable.  
**Acknowledgments:** This work was performed using the equipment of the Shared Research Center \"Analytical center of deep oil processing and petrochemistry of TIPS RAS\". Authors thanks to [PERSON] to provide SEM images. [PERSON] acknowledges KAUST for support.  
**Conflicts of Interest:** The authors declare no conflict of interest.