KWR Kees Roest by KWR Kees Roest
03 April 2019

Ion-exchange membranes for (waste)water treatment

Functional membranes based on covalent incorporation of a functionalized monomer facilitate selective electro-driven transport of phosphate or citrate from model dairy wastewater. The presented approach has the potential to prepare ion-exchange membranes that address other ions that are environmentally relevant. In this way selective membrane transport of ions can be controlled....

Functionalized Anion-Exchange Membranes Facilitate Electrodialysis of Citrate and Phosphate from Model Dairy Wastewater

Scheme 1 shows the two-step synthesis developed to obtain the guanidinium acrylate monomer. Guanidinopropanol (1) was synthesized according to Funhoff et al.(34) In detail, 8.54 mmol of 3-aminopropanol was slowly added to 8.54 mmol of 2-ethyl-2-thiopseudourea hydrobromide in a 100 mL flask. Subsequently, 2 mL of Milli-Q water was added. The solution was stirred overnight at room temperature. Next, water was removed under reduced pressure to obtain a viscous transparent liquid (yield 16.47 mmol, 96%). For the synthesis of the guanidinium acrylate monomer (2), compound 1 (1.67 g = 8.43 mmol) was stirred in acetonitrile (5 mL) at room temperature for 1 h. Freshly activated molecular sieves (4 Å, Sigma) were added to the solution in order to remove residual amounts of water. Triethylamine (0.85 mL = 8.43 mmol) was added dropwise, followed by the dropwise addition of 0.76 mL (8.43 mmol) of acryloyl chloride. The solution was stirred for 24 h and kept in an ice bath to avoid prepolymerization. The acetonitrile was removed under vacuum. Product 2 was washed with EtAc/EtOH (1/1) to remove any Et3N and filtered to remove the molecular sieves. Purification was done by column chromatography using MeOH/EtAc (20/80) as eluent. 1H NMR spectra were...

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