Abstract
In this study, a novel polybenzimidazole (PBI)-based organic solvent nanofiltration (OSN) membrane possessing excellent stability under high pH condition was developed. To improve the chemical stability, the pristine PBI membrane was crosslinked with a silane precursor containing an epoxy end group. In detail, hydrolysis and condensation reaction of methoxysilane in the 3-glycidyloxypropyl trimethoxysilane (GPTMS) yields organic–inorganic networks within the PBI membrane structure. At the same time, the epoxy end groups on the organosiloxane network (Si–O–Si) reacted with amine groups of PBI to complete the crosslinking. The resulting crosslinked PBI membrane exhibited a good stability upon exposure to organic solvents and was not decomposed even in basic solution (pH 13). Our membrane showed an ethanol permeance of 27.74 LMHbar−1 together with a high eosin Y rejection of >90% under 10 bar operation pressure at room temperature. Furthermore, our PBI membrane was found to be operational even under an extremely basic condition, although the effective pore size was slightly enlarged due to the pore swelling effect. The results suggest that our membrane is a promising candidate for OSN application under basic conditions.
Highlights
Organic solvents are heavily utilized in the pharmaceutical and petrochemical industries as indispensable resources [1]
Compared to pristine PBI, the characteristic band at 1099 cm−1 is shown in the spectrum of the modified PBI membrane, which can be attributed to the Si–O–Si bond
This implies that the siloxane network is successfully formed within the PBI membrane by the condensation reaction of GPTMS [29,30,31]
Summary
Organic solvents are heavily utilized in the pharmaceutical and petrochemical industries as indispensable resources [1]. Reaction mixtures used in pharmaceutical productions typically contain c.a. 85% of organic solvents [2]. In the pharmaceutical and petrochemical industries, an efficient separation of organic solvents should be implemented to reduce energy consumption, and to promote the recycling of solvents. In this context, organic solvent nanofiltration (OSN) or solvent-resistant nanofiltration has been emerging as a desired separation process due to several advantages over conventional processes such as low energy consumption and operation cost [4,5,6]. Modular design and small footprint, which are key advantages of membrane-based separation, are highly beneficial in practical applications
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