Synthesis and characterization of nanoporous polyethersulfone membrane as support for composite membrane in CO2 separation: From lab to pilot scale

Abstract

Nanoporous polyethersulfone (PES) membranes were prepared from PES/N-methyl-2pyrrolidone (NMP)/2-methoxyethanol (2-ME) casting solutions with water as coagulant by both vapor-and non-solvent-induced phase inversion steps successively under various preparation parameters. 2-ME was incorporated into the casting solution as a pore-forming additive because of its high affinity with water, leading to more open membrane morphology. A detailed study of the effects of different parameters, including polymer concentration, 2-ME/NMP ratio, relative humidity, water vapor exposure time, and water coagulation bath temperature, was conducted in lab-scale experiments to determine the operation guidelines for pilot-scale fabrication. 14-inch wide PES membranes were fabricated successfully by using a continuous casting machine. Parametric studies in pilot-scale fabrication were also carried out. Surface morphologies of PES membranes were characterized by scanning electron microscopy (SEM). The morphological differences between both scales by the same preparation conditions were compared. Based on the guidelines established from lab-scale experiments, the casting solution composition and coagulation bath temperature were optimized in a pilot-scale continuous casting machine to fabricate the 14-inch wide PES membrane with a desired morphology suitable for use as the substrate of composite membranes in CO 2 separation. The studied fabrication process also showed the potential for the commercial production of the PES membrane in a larger scale by the vapor-and non-solvent-induced phase inversion technique.

Improved microfiltration and bacteria removal performance of polyethersulfone membranes prepared by modified vapor‐induced phase separation

“…During this step, the mass transfer and exchange rate of solvent/non‐solvent decrease and different membrane morphologies can be obtained . Some researchers have studied the effect of VIPS condition on the membrane morphology and performance . It has been demonstrated that by the using of VIPS technique, the formation of macrovoids is suppressed and typical symmetric spongy‐like morphology with cellular structure can be obtained.…”

“…Another strategy to alter the mass transfers of phase separation process and control the membrane morphology is addition of non‐solvent in the casting solution . In the presence of non‐solvent additive, the surface properties and porosity of the membrane can be improved . Li et al pointed out that the addition of a low molecular weight non‐solvent such as diethylene glycol can reduce the precipitation rate and create membrane with spongy‐like structure instead of macrovoid morphology .…”

“…[8][9][10] Some researchers have studied the effect of VIPS condition on the membrane morphology and performance. 8,[10][11][12][13][14][15] It has been demonstrated that by the using of VIPS technique, the formation of macrovoids is suppressed and typical symmetric spongy-like morphology with cellular structure can be obtained.…”

“…16,17 In the presence of non-solvent additive, the surface properties and porosity of the membrane can be improved. 11 Li et al pointed out that the addition of a low molecular weight non-solvent such as diethylene glycol can reduce the precipitation rate and create membrane with spongy-like structure instead of macrovoid morphology. 10 The addition of 2methoxyethanol (2-ME) had similar effect on the morphology of membranes prepared by both vapor-induced and non-solvent induced processes.…”

Fabrication optimization of polyethersulfone (PES)/polyvinylpyrrolidone (PVP) nanofiltration membranes using Box–Behnken response surface method

“…Among them, PES, which has an excellent separation performance and high thermal, chemical, hydraulic and mechanical stability, has been used in a wide range of membrane applications. [27][28][29][30] Furthermore, it can be used achieve asymmetric structures with various pore size ranges by controlling the chemical and physical conditions applied in the phase inversion process. The most important and effective parameters in the fabrication of NF membranes are polymer concentration, type of solvent and non-solvent, pore-forming agent, temperature of the coagulation bath and solvent evaporation time.…”