The Effect of a Hydrophilic Polymer on the Morphology of Polymeric Membranes and the Retention of Metals

Polyethylene glycol (PEG) is a preferred hydrophilic polymer as an additive for casting solutions. In this study, polymeric membranes containing 1,10-phenanthroline and different molecular weights of polyethylene glycol (PEG) are tested for the morphological change and metal retention on the membrane surface. Additives in the form of PEGs with molecular weights of 400 Da, 600 Da, and 6000 Da were used. The morphology of each membrane was examined using scanning electron microscopy (SEM). It appears that copper has more retention than cadmium in all membrane components in SEM-EDS analysis. FTIR spectra findings provided evidence that PEG binds to the PVC backbone through hydrogen bonds involving chlorine atoms in the PVC and hydrogen atoms in the hydroxyl groups of PEG. The porosity of the membrane was determined by gravimetric method. The molecular weight of PEG in the membrane seems to be increasing, the porosity of the membrane improved. The porosity of the membrane obtained with PVC/ PEG/ 1,10-phenanthroline is 62.85 for PEG 400, 80.00 for PEG 600 and 83.50 for PEG 6000. The order of metal retention on the surface of the membranes consisting of PVC-1,10 phenanthroline and PEGs are Cu > Cd, indicating that with its large diameter (140 pm), cadmium cannot settle into the pores as much as copper. Except for PEG 600, the retention of both metals decreased with the addition of phenanthroline to the membrane containing PEG. The amorphous structure was detected from the XRD of the membranes. Thermal analysis of the membrane was determined by TG-DSC.