Highly selective polybenzoxazinoneimide vs. its nonselective prepolymer in separation of water-ethanol mixture: Role of sorption parameters in pervaporation performance

ABSTRACT

Relationship between structure and transport properties of two polyheteroarylenes is studied on the example of polybenzoxazinoneimide (PBOI) and its prepolymer – polyamic acid imide-containing (PAAI). Formation of dense membranes, determination of their physical parameters, and control of membrane morphology by SEM were carried out. Transport properties of the membranes in the separation of the water – ethanol mixture were determined by sorption and pervaporation experiments. The equilibrium sorption degree, diffusivity, as well as sorption selectivity and diffusion selectivity of the PAAI and PBOI membranes were considered. The pervaporation experimental data on the total flux and the separation factor of the membranes were converted into permeability and selectivity to estimate the performance of the membranes. Due to the – COOH groups in the structure, PAAI membrane exhibits significantly higher sorption degree of water (4 times more) and ethanol (10 times more) as compared with those of PBOI. However, the PAAI membrane has water/ethanol sorption selectivity lower than 1, which indicates the absence of separation efficiency in the ethanol dehydration. In contrast, the PBOI membrane is very effective in the ethanol dehydration as the separation factor reaches 9000 in pervaporation of the mixture containing 10 wt% water.

KEYWORDS:

• Polybenzoxazinoneimide
• ethanol dehydration
• pervaporation
• sorption
• selectivity

Acknowledgements

A.P. thanks the grant of the President RF [MK-1280.2020.3]. Equipment of Resource Centers of St. Petersburg State University, namely, the Interdisciplinary Resource Center “Nanotechnologies,” “Thermogravimetric and calorimetric methods of investigation” and “Cryogenic Department” were used for membrane investigations.

Disclosure Statement

The authors declare that there is no conflict of interest.

Author Contributions

Membrane formation, physicochemical investigation, analysis of transport properties, and article writing were carried out by Galina Polotskaya, Alexandra Pulyalina, and Ilya Faykov. The polymers were synthesized by Mikhail Goikhman and Irina Podeshvo. All authors read and approved the final manuscript.