## 1 Introduction  
Biotechnology is one of the most popular and widely developing technologies. Due to the increasing needs of the growing population, significant attention is being paid to the development of new and alternative routes for the production of chemicals from renewable feedstock [1; 2; 3; 4; 5]. One of the areas of development of green energy is the production of biofuels, such as bio-alcohols (biomethanol, bioethanol, and biobutanol), based on renewable raw materials. Biomass is one of the most promising sources for the production of liquid biofuels, and can provide up to 14% of global energy consumption [6; 7]. The most promising bio-alcohol in terms of compatibility with internal combustion engines is 1-butanol. Moreover, biobutanol can be mixed with gasoline in any ratio and has a high octane number. Compared to methanol and ethanol, butanol also has a higher combustion heat and lower volatility [8; 9; 10; 11]. Biobutanol is produced by acetone-butanol-ethanol (ABE) fermentation of a plant substrate (for example, lignin cellulasic biomass (LCB)) under the action of microorganisms [12]: _Clostridium acetobutylcium_, _Clostridium bejerinckii_, and _Clostridium saccharobutylcium_ and _saccharoperbutylacetonicum_[13; 14; 15; 16]. Using non-LCB as feedstock requires pretreatment and hydrolysis to release fermentable sugars from the biomass [17]. One of the main problems of fermentation is the low yield of butanol (up to 2 wt. %) caused by the inhibitory effect of alcohol on producing microorganisms [18]. This significantly reduces the efficiency of raw material use and increases the cost of its separation from the fermentation mixture [19]. The solution of this problem is to remove the target products from the fermentation mixture and return it to the bioreactor for further fermentation. Such an approach will make it possible to obtain a concentrated product as the output as well as to reduce the inhibitory effect of alcohols for deeper processing of raw materials. The main requirements in the process of butanol extraction from fermentation mixture are low energy consumption and the absence of negative influences of the conditions and materials used on microorganisms. To date, the following methods of biobutanol extraction, which can be integrated with ABE fermentation, have been proposed: distillation [20], adsorption [21], liquid extraction [22], reverse osmosis [23], and pervaporation [24; 25; 26; 27; 28; 29; 30; 31]. Among the presented methods, pervaporation separation is of particular interest: separation at fermentation temperatures (35-40 \({}^{\circ}\)C), isolation of microorganisms from a solution with a higher concentration of n-butanol by means of a membrane [32; 33; 34], and preservation of the productivity of microorganisms by withdrawing alcohols from the broth [35]. The combined scheme of fermentation and hydrophobic pervaporation processes makes it possible to concentrate butanol from the fermentation mixture by \(\sim\)10 times [31]. Low separation temperatures in the process of pervaporation result in low energy consumption for concentrating butanol. Thus, in previous work [36] the comparison of energy consumption for the separation of a butanol-water mixture was carried out, and it was shown that less energy is required for the pervaporation separation of the mixture (3.7 kJ/g) in comparison with adsorption (5.4 kJ/g). Extraction of bio-alcohols from fermentation mixtures using pervaporation through hydrophobic membranes is economically competitive with distillation for small to medium volumes of extraction (\(\sim\)2-20 million liters per year) [24]. The traditional membrane material for hydrophobic pervaporation is polydimethylsiloxane (PDMS) [24]. Based on PDMS, most commercial pervaporation membranes are made, such as Pervap (Sulzer Chemtech, Winterthur, Switzerland), Pervatech PDMS (Pervatech, Rijssen, The Netherlands), and PolyAn (PolyAn GmbH, Berlin, Germany) [31].