A traditional technology for removing acid gases includes absorption by aqueous solutions of alkanolamines. Despite a high degree of gas flow purification and the high productivity of this process, there is a problem of thermo-oxidative degradation of the absorption solution. Degradation products are thermally stable and tend to accumulate within the system, resulting in significant operational problems. One of the promising approaches to the regeneration of alkanolamine absorbents is combining of membrane filtration and electrodialysis. This paper presents the first study of the effect of the pore size of a membrane used for prefiltration of an alkanolamine absorbent on the efficiency of the removal of heat-stable salts (HSS) by electrodialysis. Our findings indicate that both the initial HSS content and the effectiveness of their extraction vary depending on the alkanolamine type. Such variation is determined by the different mechanisms of a resin formation in absorbent solutions depending on the alkanolamine type. It was shown that decreasing the pore size and transition from microfiltration to nanofiltration enhances the degree of HSS extraction from 55 to 65% for classical electrodialysis and up to 87% for bipolar electrodialysis. To address the issue of fouling in ion-exchange membranes, a sequential washing with acid and alkaline solutions has been proposed. Our results indicate that this method makes it possible to restore the degree of HSS extraction from absorption solutions by 95%.

Membrane separation is an efficient approach for volatile organic compounds (VOC) recovery from industrial off-gases due to its low energy consumption, compact design, and operational simplicity. The membrane-based VOC recovery critically depends on the membrane material, which must exhibit high VOC permeability and selectivity. In this study, novel sorption-selective membranes based on polydecylmethylsiloxane (PAMS-10/PDMS) were synthesized using α,ω-dienes of varying lengths as cross-linkers: 1,7-octadiene (OD), 1,9-decadiene (DD), and 1,11-dodecadiene (DdD). The cross-linker lengths were chosen to be shorter than, equal to, or longer than the PAMS-10/PDMS n-decyl side-chain substituent, enabling a systematic investigation of polymer supramolecular structure effects on transport properties.The influence of cross-linker concentration and length on mechanical, structural, sorption, and transport properties was examined in detail. The combination of three independent experimental methods (time-lag, vapor permeation, and in situ spectroscopic ellipsometry) revealed that increasing α,ω-diene concentration and decreasing its length led to a reduction in the diffusivity and permeability of permanent gases, gaseous hydrocarbons and VOC vapors. WAXD-analysis confirmed that n-alkyl side chains formed an interdigitated packing, with the interplanar distance decreasing by up to 0.5 Å which increasing cross-linking density.For VOC/N2 separation, the slightly cross-linked OD-1 membrane and the DdD-5 membrane, cross-linked with long 1,11-dodecadiene, demonstrated mixed-gas selectivities of 950/921/314/840 and 940/1086/233/1106 for toluene/n-octane/i-octane/n-butyl acetate, respectively, significantly exceeding the values reported for conventional PDMS-membranes. Notably, the DD-5 membrane, cross-linked with 1,9-decadiene, matching the length of PAMS-10/PDMS side chain substituent, exhibited mixed-gas selectivity comparable to the ideal selectivity, a unique behavior attributed to optimal supramolecular organization. These findings establish PAMS-10/PDMS membranes as highly efficient materials for VOC recovery applications, highlighting the versatility of cross-linker modification for adjusting transport characteristics.

Comparative analysis of membrane materials was provided for the recovery of volatile organic compounds (VOCs) from vapor-gas mixtures generated during petroleum product loading operations. Mathematical modeling of membrane separation in a countercurrent mode was used to evaluate the effectiveness of two different membranes: polydecylmethylsiloxane (C10) and polydimethylsiloxane (PDMS), for recovery n-octane vapors, a model component limiting mass transfer during gasoline fraction recovery. Calculations were performed for a rail tank car loading and unloading process with a capacity of 830 m³/h and a target VOC recovery rate of 90%. It was found that the high selectivity of C10 with respect to n-octane vapor provides significant technological advantages, such as an increase in the concentration of n-octane in the permeate stream and a decrease in specific energy consumption. With a decrease in permeate pressure from 10 to 2 kPa, the required area of C10 membranes is shown to decrease by 6 times and for PDMS membranes by only 2.7 times. The costs of the membranes and energy consumption for VOC recovery from one railway tank car were estimated. The results obtained support the potential of using highly selective C10 membranes to create energy-efficient VOC recovery units for oil refining.

Membrane separation is an efficient approach for volatile organic compound (VOC) recovery from industrial off-gases due to its low energy consumption, compact design, and operational simplicity. Membrane-based VOC recovery critically depends on the membrane material, which must exhibit high VOC permeability and selectivity under mixed-gas conditions. In this study, novel highly selective membranes for VOC removal based on polydecylmethylsiloxane (PAMS-10) were synthesized using both polydimethylsiloxane and various α,ω-dienes as cross-linkers: 1,7-octadiene (OD), 1,9-decadiene (DD), and 1,11-dodecadiene (DdD). The influence of cross-linker concentration and length on mechanical, structural, sorption, and transport properties was examined extensively. The combination of three independent experimental methods (time-lag, vapor permeation, and in situ spectroscopic ellipsometry) revealed that increasing α,ω-diene concentration and decreasing its length led to a reduction in the diffusivity and permeability of permanent gases, gaseous hydrocarbons, and VOC vapors. For VOC/N₂ separation, the slightly cross-linked OD-1 membrane and the DdD-5 membrane, cross-linked with long 1,11-dodecadiene, demonstrated outstanding mixed-gas selectivities of 950/921/314/840 and 940/1084/233/1106 for toluene/n-octane/i-octane/n-butyl acetate, respectively. Notably, the DD-5 membrane, cross-linked with 1,9-decadiene, matching the length of the PAMS-10 side chain substituent, exhibited the best mechanical properties and mixed-gas selectivity comparable to the ideal selectivity, a unique behavior attributed to optimal supramolecular organization.