Spectroscopy To determine the concentration of salts pre-and post desalination experiments, permanent low magnetic field (in the range 1-2 T) as opposed to the conventional high field 1 H and 13 C NMR (range 5-25 T) magnet was used as a benchtop NMR. It uses multi-nuclear sensor to analyze various nuclei ( 23 Na, Cl and 39 K) and provide their ionic concentrations within a given solution under investigation. 18 Differential scanning calorimetry (DSC) was used to measure the melting temperature of PEI-C16-33% and -20%. PEI residues were heated using a TA Instrument DSC250 differential scanning calorimeter at 10 °C•min -1 from 25 °C to 200 °C under a nitrogen atmosphere with a flowrate of 50 mL•min -1 .