Monitoring the Interfacial Polymerization of Piperazine and Trimesoyl Chloride with Hydrophilic Interlayer or Macromolecular Additive by In Situ FT-IR Spectroscopy

Abstract

The interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC) has been extensively utilized to synthesize nanofiltration (NF) membranes. However, it is still a huge challenge to monitor the IP reaction, because of the fast reaction rate and the formed ultra-thin film. Herein, two effective strategies were applied to reduce the IP reaction rate: (1) the introduction of hydrophilic interlayers between the porous substrate and the formed polyamide layer, and (2) the addition of macromolecular additives in the aqueous solution of PIP. As a result, in situ Fourier transform infrared (FT-IR) spectroscopy was firstly used to monitor the IP reaction of PIP/TMC with hydrophilic interlayers or macromolecular additives in the aqueous solution of PIP. Moreover, the formed polyamide layer growth on the substrate was studied in a real-time manner. The in situ FT-IR experimental results confirmed that the IP reaction rates were effectively suppressed and that the formed polyamide thickness was reduced from 138 ± 24 nm to 46 ± 2 nm according to TEM observation. Furthermore, an optimized NF membrane with excellent performance was consequently obtained, which included boosted water permeation of about 141–238 (L/m2·h·MPa) and superior salt rejection of Na2SO4 > 98.4%.

Adsorption Characteristics and Mechanisms of Fe-Mn Oxide Modified Biochar for Pb(II) in Wastewater

“…In general, a higher electronegativity value for metal ions results in a stronger attractive force with FM-BC, and a smaller radius of hydrated ions for metal ions results in a greater affinity with FM-BC [ 37 , 38 ]. The electronegativity values of Ca(II), Mg(II), Zn(II), and Pb(II) are 1.00, 1.31, 1.65, and 2.33, respectively, and the radius of the hydrated ions are 4.12, 4.28, 4.30, and 4.01 Å, respectively [ 39 , 40 , 41 ]. Unlike these three metal ions, Pb(II) has a higher electronegativity and a smaller hydrated ion radius.…”

Recent advances in thin film nanocomposite membranes containing an interlayer (TFNi): fabrication, applications, characterization and perspectives

“…9(a) , Yang et al used in situ infrared spectroscopy to study the IP reaction in real time and successfully established a relationship between the thickness of the PA layer and the rate of the IP reaction. 151 IP reactions on the PSf substrate were monitored using FT-IR spectroscopy. Usually, FT-IR spectroscopy can monitor a reaction for a few hours.…”

High performance cellulose acetate/polyamide (CA/PA) thin film composite forward osmotic (TFC‐FO) membranes from dual solvent modification processes

“…Additional methods included modulating the IP process by adding additives, 19–22 applying surface active agent and using co‐solvents 23–27 ; and post‐treating the PA layers by acid/alkali hydrolysis, 28 solvent activation and ionic liquid treatment 29–32 . Adding co‐solvent in the IP process could modulate the inter phase miscibility and the diffusion rates of monomers 27,33,34 . Duan et al 27 added hexamethyl phosphoramide (HMPA) to form thicker and more hydrophilic PA layers with 1.73 times higher water flux but slightly decreased NaCl rejection.…”

“…[29][30][31][32] Adding co-solvent in the IP process could modulate the inter phase miscibility and the diffusion rates of monomers. 27,33,34 Duan et al 27 added hexamethyl phosphoramide (HMPA) to form thicker and more hydrophilic PA layers with 1.73 times higher water flux but slightly decreased NaCl rejection. Activation solvent could dissolve un-reacted monomers and swell the formed PA matrix to become more water permeable.…”