In-situ generation of iron-dopamine nanoparticles with hybridization and cross-linking dual-functions in poly (vinyl alcohol) membranes for ethanol dehydration via pervaporation

Effect of Nanofillers on Properties and Pervaporation Performance of Nanocomposite Membranes: A Review

In recent years, a well-known membrane-based process called pervaporation (PV), has attracted remarkable attention due to its advantages for selective separation of a wide variety of liquid mixtures. However, some restrictions of polymeric membranes have led to research studies on developing membranes for efficient separation in the PV process. Recent studies have focused on preparation of nanocomposite membranes as an effective method to improve both selectivity and permeability of polymeric membranes. The present study provides a review of PV nanocomposite membranes for various applications. In this review, recent developments in the field of nanocomposite membranes, including the fabrication methods, characterization, and PV performance, are summarized.

Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS2)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes: Enhanced Dye Separation Performance

Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS₂ (MoS₂@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS₂@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS₂@PDA MMMs with different concentrations were obtained. The addition amount of MoS₂@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m⁻² h⁻¹ bar⁻¹. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na₂SO₄ 10.52%, MgSO₄ 4.64%, and MgCl₂ 1.55%, reflecting the potential for separating salts and dyes of MoS₂@PDA/PES MMMs.

Poly(vinyl alcohol)-Modified Membranes by Ti3C2T x for Ethanol Dehydration via Pervaporation

In this paper, PVA/Ti3C2T x mixed matrix membranes (MMMs) were prepared by mixing the synthesized Ti3C2T x with the PVA matrix, and the pervaporation (PV) performance of the ethanol-water binary system was tested. The morphology, structural properties, and surface characteristics of the membranes were investigated by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, degree of swelling, and water contact angle. The PVA/Ti3C2T x MMMs exhibit excellent compatibility and swelling resistance. Moreover the effects of the Ti3C2T x filling level, feed concentration, and operating temperature on the ethanol dehydration performance were systematically studied. The results demonstrated that the separation factor of PVA/Ti3C2T x MMMs was significantly increased because of Ti3C2T x promoting the cross-linking density of the membrane. Specifically, the membrane showed the best PV performance when Ti3C2T x loading was 3.0 wt %, achieving a separation factor of 2585 and a suitable total flux of 0.074 kg/m2 h for separating 93 wt % ethanol solution at 37 °C.

Development of in situ synthesized Y-based nanoparticle/polyethersulfone adsorptive membranes by adjusting the composition of the coagulation bath for enhanced removal of fluoride

The composition of coagulation bath significantly altered the membrane structure, composition and adsorption performance for defluoridation by affecting the phase inversion kinetics.

Preparation of graphene oxide/poly(vinyl alcohol) composite membrane and pervaporation performance for ethanol dehydration

Although poly(vinyl alcohol) (PVA) membranes are widely used in solvent dehydration by pervaporation, the separation factor is rather limited. Considering this, novel PVA mixed matrix membranes with graphene oxide (GO) nanosheets were prepared. poly(acrylonitrile) ultrafiltration (PAN) membrane was used as support layer. The PVA/GO composite membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, thermogravimetric analysis and water contact angle. We also explored the pervaporation performance of the membrane for ethanol dehydration. GO slightly improves the thermal stability and crystallinity of the composite membranes. In addition, the hydrophilicity of the composite membranes is weakened after GO addition, but the crosslinking degree is increased, resulting a significant increase in the separation factor and a certain decrease in the total flux. With the amount of GO addition increases, the total flux of the PVA/GO composite membrane decreases, while the separation factor increases first and then decreases, and the preferred amount of GO addition is 2.0 wt%. Especially, the separation factor of the composite membranes with 2.0 wt% GO addition could reach 3 059, which is 16 times higher than PVA membranes, with the corresponding permeability flux is 145 g m⁻² h⁻¹.

The separation factor of the composite GOP-2.0 membranes could reach 3 059, which is 16 times higher than PVA membranes.