Abstract <p>The transport and separation characteristics of the composite membrane with a selective layer based on a copolymer of polydecylmethylsiloxane and polymethylpentafluoropropylsiloxane (50F5) were studied during the pervaporation recovery of <i>n</i>-butanol from aqueous mixtures. It was shown that the membrane with the selective layer of copolymer (M-50F5 exhibits a high separation factor for <i>n</i>-butanol/water (35) and a total permeate flux of 0.31 kg/(m² h). For the first time, an analysis of the impact of concentration polarization on the efficiency of <i>n</i>-butanol recovery from a model fermentation mixture was conducted, including the calculation of the concentration polarization modulus and the thickness of the diffusion boundary layer. It was revealed that increasing the flow rate of the feed mixture above 30 cm/s eliminates concentration polarization effects, as evidenced by a reduction in the boundary layer thickness to zero. Optimization of the hydrodynamic regime allowed for the minimization of mass transfer limitations caused by concentration polarization, particularly at low butanol concentrations. The obtained results substantiate the potential of using 50F5-based membranes for the pervaporation recovery of butanol from fermentation broths and open new opportunities for improving separation technologies for multicomponent systems.</p>