Tailoring Charged Nanofiltration Membrane Based on Non-Aromatic Tris(3-aminopropyl)amine for Effective Water Softening

Abstract

High-performance positively-charged nanofiltration (NF) membranes have a profound significance for water softening. In this work, a novel monomer, tris(3-aminopropyl)amine (TAEA), with one tertiary amine group and three primary amine groups, was blended with trace amounts of piperazine (PIP) in aqueous solution to fabricate a positively-charged NF membrane with tunable performance. As the molecular structures of TAEA and PIP are totally different, the chemical composition and structure of the polyamine selective layer could be tailored via varying the PIP content. The resulting optimal membrane exhibited an excellent water permeability of 10.2 LMH bar−1 and a high rejection of MgCl2 (92.4%), due to the incorporation of TAEA/PIP. In addition, this TAEA NF membrane has a superior long-term stability. Thus, this work provides a facile way to prepare a positively charged membrane with an efficient water softening ability.

Applications of Ion Exchange Resins in Water Softening

“…For decreasing the content of hardness ions, different softening techniques have been developed. It is necessary to mention baromembrane methods: combination of chemical precipitation with microfiltration [1], polymer-assisted ultrafiltration [2] (as shown in the example of whey filtration, ultrafiltration membrane rejects up to 10-15% of hardness ions [3] without addition of macromolecular compound to the liquid being desalinated), nanofiltration [4], reverse osmosis [5]. Chemical methods (precipitation of insoluble calcium and magnesium compounds with caustic [6] and lime [7] soda) can be related to very old times and are widespread.…”

A Novel Approach for the Development of Low-Cost Polymeric Thin-Film Nanocomposite Membranes for the Biomacromolecule Separation

“… 9 The separation of biomacromolecules using membrane technology depend on the kind of materials used and the properties of the proteins such as surface charges, their interactions, and the differences in the size of the proteins. 10 The pressure-driven nanofiltration (NF) membrane has been emerging with outstanding results in the separation process, typically in the field of water desalination, 11 , 12 wastewater treatment, 13 water purification, 14 water softening, 15 food, 16 biotechnology, 17 and pharmaceutical industries. 18 NF membrane technology is a promising option for separation as the products obtained undergo no chemical or biological changes along with less energy expenditure.…”

Intrinsic Dependence of Groundwater Cation Hydraulic and Concentration Features on Negatively Charged Thin Composite Nanofiltration Membrane Rejection and Permeation Behavior

“…Researchers in a recently reported study fabricated a positively charged nanofiltration membrane that was used for effective separation of Mg 2+ and Li + from saltlake brine with a high Mg 2+ /Li + mass ratio [8]. Jin et al developed a positively charged nanofiltration membrane of excellent stability via interfacial polymerization reaction on a polyethersulfone substrate used for water softening [9]. Crossflow filtration rejects inorganic hydrated cations depending on electrical charge, valence, and hydration degree, as well as their concentration and possible interactions with other present ions.…”