Effect of the Formation of Ultrathin Selective Layers on the Structure and Performance of Thin-Film Composite Chitosan/PAN Membranes for Pervaporation Dehydration

Abstract

The aim of the study is to improve the performance of thin-film composite (TFC) membranes with a thin selective layer based on chitosan (CS) via different approaches by: (1) varying the concentration of the CS solution; (2) changing the porosity of substrates from polyacrylonitrile (PAN); (3) deposition of the additional ultrathin layers on the surface of the selective CS layer using interfacial polymerization and layer-by-layer assembly. The developed membranes were characterized by different methods of analyses (SEM and AFM, IR spectroscopy, measuring of water contact angles and porosity). The transport characteristics of the developed TFC membranes were studied in pervaporation separation of isopropanol/water mixtures. It was found that the application of the most porous PAN-4 substrate with combination of formation of an additional polyamide selective layer by interfacial polymerization on the surface of a dense selective CS layer with the subsequent layer-by-layer deposition of five bilayers of poly (sodium 4-styrenesulfonate)/CS polyelectrolyte pair led to the significant improvement of permeance and high selectivity for the entire concentration feed range. Thus, for TFC membrane on the PAN-4 substrate the optimal transport characteristics in pervaporation dehydration of isopropanol (12–90 wt.% water) were achieved: 0.22–1.30 kg/(m2h), 99.9 wt.% water in the permeate.

Extraction of Organic Volatile Pollutants in Over-Saturated Water by Pervaporation Technique Using a Poly (Dimethylsiloxane)-Based Sealer as a Membrane

“…Regarding the variation of the selectivity with the membrane thickness (inset in Figure 5), the curve profile indicates a significant increase in which a maximum selectivity of 2988 is reached for the 510-µm-thick membrane during a period of 1.5 h of the separation process. The increase of the selectivity with the increase of the membrane thickness agrees with comparable results reported in the literature [62][63][64][65].…”

Modification of Polysulfone Ultrafiltration Membranes via Addition of Anionic Polyelectrolyte Based on Acrylamide and Sodium Acrylate to the Coagulation Bath to Improve Antifouling Performance in Water Treatment

“…Modification by polyelectrolyte is a promising approach for development of antifouling membranes due to polyelectrolyte’s high hydration ability, possibility to tune surface charge and versatility of chemistry, structure and modification techniques which can be implemented [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Moreover, modification by polyelectrolytes is a flexible instrument for design of thin film composite membranes for microfiltration [ 29 ], ultrafiltration (UF) [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ], nanofiltration (NF) [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ,…”

“…Moreover, polyelectrolyte multilayers can serve as defect-healing [ 61 ] and sacrificial layers [ 49 , 56 ] to remove adsorbed foulants from membrane surface. Both coating and LBL techniques can be followed by cross-linking [ 58 ] to enhance membrane stability and carried out in physical adsorption mode (dip-coating) [ 59 , 60 ] or dynamic mode [ 62 , 63 , 64 ] to decrease time of membrane formation. The main disadvantage of polyelectrolyte multilayer membranes is that their stability highly depends on pH and ionic strength of the feed [ 53 ].…”

Purification, characterization, and determination of biological activities of water-soluble polysaccharides from Mahonia bealei

“…The process of ultrafiltration is shown in the Fig. 1 below:

Figure 1 Ultrafiltration setup: 1—Tank (containing nitrogen), 2—Regulator (for pressure), 3—Manometer, 4—Membrane, 5—Stirred ultrafiltration cell, 6—Magnetic stirrer, 7—Container (for permeate), Figure adopted from 44 .

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