scholarly journals Two-dimensional fractal nanocrystals templating for substantial performance enhancement of polyamide nanofiltration membrane

2021 ◽  
Vol 118 (37) ◽  
pp. e2019891118
Author(s):  
Yang Lu ◽  
Ruoyu Wang ◽  
Yuzhang Zhu ◽  
Zhenyi Wang ◽  
Wangxi Fang ◽  
...  
Keyword(s):  
Performance Enhancement ◽  
Interfacial Polymerization ◽  
Water Flux ◽  
Practical Method ◽  
Curing Temperature ◽  
Polymerization Process ◽  
Nanofiltration Membrane ◽  
Two Dimensional ◽  
Fractal Structures ◽  
Templating Method

In this study, we report the emergence of two-dimensional (2D) branching fractal structures (BFS) in the nanoconfinement between the active and the support layer of a thin-film-composite polyamide (TFC-PA) nanofiltration membrane. These BFS are crystal dendrites of NaCl formed when salts are either added to the piperazine solution during the interfacial polymerization process or introduced to the nascently formed TFC-PA membrane before drying. The NaCl dosing concentration and the curing temperature have an impact on the size of the BFS but not on the fractal dimension (∼1.76). The BFS can be removed from the TFC-PA membranes by simply dissolving the crystal dendrites in deionized water, and the resulting TFC-PA membranes have substantially higher water fluxes (three- to fourfold) without compromised solute rejection. The flux enhancement is believed to be attributable to the distributed reduction in physical binding between the PA active layer and the support layer, caused by the exertion of crystallization pressure when the BFS formed. This reduced physical binding leads to an increase in the effective area for water transport, which, in turn, results in higher water flux. The BFS-templating method, which includes the interesting characteristics of 2D crystal dendrites, represents a facile, low-cost, and highly practical method of enhancing the performance of the TFC-PA nanofiltration membrane without having to alter the existing infrastructure of membrane fabrication.

Effects of DMSO and glycerol additives on the property of polyamide reverse osmosis membrane

2016 ◽  
Vol 74 (7) ◽  
pp. 1619-1625 ◽  
Author(s):  
Fengjing Wu ◽  
Xiaojuan Liu ◽  
Chaktong Au
Keyword(s):  
Contact Angle ◽  
Reverse Osmosis ◽  
Water Contact Angle ◽  
Interfacial Polymerization ◽  
Water Flux ◽  
Cross Flow ◽  
Interfacial Free Energy ◽  
Polymerization Process ◽  
Water Contact ◽  
Salt Rejection

The polyamide reverse osmosis (RO) membranes were prepared through interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The use of dimethyl sulfoxide (DMSO) and glycerol as additives for the formation of thin-film composite (TFC) was investigated. We studied the effect of DMSO and glycerol addition on membrane property and RO performance. Microscopic morphology was examined by atomic force microscopy and scanning electron microscopy. The surface hydrophilicity was characterized on the basis of water contact angle and surface solid–liquid interfacial free energy (−ΔGSL). Water flux and salt rejection ability of the membranes prepared with or without the additives were evaluated by cross-flow RO tests. The results reveal that the addition of DMSO and glycerol strongly influences the property of the TFC RO membrane. Compared to the MPD/TMC membrane fabricated without DMSO and glycerol, the MPD/TMC/DMSO/glycerol membrane has a rougher surface and is more hydrophilic, showing smaller water contact angle and larger −ΔGSL value. Without decrease in salt rejection ability, the MPD/TMC/DMSO/glycerol membrane shows water flux significantly larger than that of the MPD/TMC membrane. The unique property of the MPD/TMC/DMSO/glycerol membrane is attributed to the cooperative effect of DMSO and glycerol on membrane structure during the interfacial polymerization process.

Study on Compositions in Aqueous Phase of Hollow Fiber Composite Nanofiltration Membrane

2012 ◽  
Vol 529 ◽  
pp. 569-573 ◽  
Author(s):  
Lei Wen ◽  
Wei Wang
Keyword(s):  
Phase Composition ◽  
Aqueous Phase ◽  
Hollow Fiber ◽  
Interfacial Polymerization ◽  
Fiber Composite ◽  
Water Flux ◽  
Sulfamic Acid ◽  
Nanofiltration Membrane ◽  
Trimesoyl Chloride ◽  
Polymerization Method

Hollow fiber composite nanofiltration (NF) membranes were prepared by interfacial polymerization method, with polysulfone (PSF) hollow fiber ultrafiltration membrane as base membrane, piperazine (PIP) as the aqueous phase monomer and trimesoyl chloride (TMC) as the organic phase monomer. The effects of aqueous phase composition on composite NF were discussed. The experimental results show that the optimum compositions in aqueous phase: 1wt% PIP, 0.05wt% MPDA, 1wt% TEA, 3wt% sulfamic acid. The best rejection to MgSO4 was 94.7%, and water flux was 66.1L•m-2•h-1.

Preparation of three-bore hollow fiber charged nanofiltration membrane for separation of organics and salts

2012 ◽  
Vol 65 (1) ◽  
pp. 171-176 ◽  
Author(s):  
Jianmian Deng ◽  
Yatao Zhang ◽  
Jindun Liu ◽  
Haoqin Zhang
Keyword(s):  
Hollow Fiber ◽  
Interfacial Polymerization ◽  
Xylenol Orange ◽  
Water Flux ◽  
Strong Acid ◽  
Solute Concentration ◽  
Operating Pressure ◽  
Nanofiltration Membrane ◽  
Nacl Concentration ◽  
Temperature Solution

Three-bore hollow fiber charged nanofiltration (NF) membrane was prepared by interfacial polymerization (IP). The results showed that the flux and rejection of NF membrane prepared in this study increased with the increasing in the operating pressure. The water flux decreased and rejection for obvious dyes increased as the solute concentration increased. The separation factor for mixture of Xylenol orange/NaCl decreased when NaCl concentration in solution increased and could reach to as high as 18. In addition, three-bore hollow fiber charged nanofiltration membrane prepared in this study has excellent stability for strong acid (pH = 3), strong alkali (pH = 11) and high temperature solution (80 °C).

scholarly journals Single-File Water Flux Through Two-Dimensional Nanoporous Membranes

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Myung Eun Suk
Keyword(s):  
Water Flux ◽  
Interaction Strength ◽  
High Water ◽  
Potential Of Mean Force ◽  
Proximal Region ◽  
Dominant Factor ◽  
Chemical Characteristics ◽  
Nanoporous Membranes ◽  
Two Dimensional ◽  
Single File

Abstract Recent advances in the development of two-dimensional (2D) materials have facilitated a wide variety of surface chemical characteristics obtained by composing atomic species, pore functionalization, etc. The present study focused on how chemical characteristics such as hydrophilicity affects the water transport rate in hexagonal 2D membranes. The membrane–water interaction strength was tuned to change the hydrophilicity, and the sub-nanometer pore was used to investigate single-file flux, which is known to retain excellent salt rejection. Due to the dewetting behavior of the hydrophobic pore, the water flux was zero or nominal below the threshold interaction strength. Above the threshold interaction strength, water flux decreased with an increase in interaction strength. From the potential of mean force analysis and diffusion coefficient calculations, the proximal region of the pore entrance was found to be the dominant factor degrading water flux at the highly hydrophilic pore. Furthermore, the superiority of 2D membranes over 3D membranes appeared to depend on the interaction strength. The present findings will have implications in the design of 2D membranes to retain a high water filtration rate.

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