Effect of PEG additives on performance of hemodialysis membrane

Abstract

Dialysis membranes are fast gaining importance nowadays in membrane separation industries, mainly used in medical industry to remove uremic toxic, excess water and undesirable protein out of the human blood. Unfortunately, the current trend of dialysis technology in Malaysia still depends on foreign countries and the development of dialysis industries are far behind the world latest era. Therefore, the main objective of this study is to develop flat sheet membranes, suitable for dialysis of biomolecules such as urea and determine the optimum formulation for the dialysis membrane produced. The performance of the cellulose acetate membranes produced using various dope solution formulations were studied by varying the acetic acid (Acc)/polyethylene glycol (PEG) ratio and the amount of water as well as the different molecular weight PEG used. Three different additives were used namely PEG 200, PEG 400 and PEG 600 in the membrane formulations. The membranes were tested using a single layer continuous dialysis system. The molecular weight cut off clearance efficiency range, the permeability and sieving properties of the dialysis membranes were determined. The response surface method, central composite design was applied to construct the experimental trials for this study. Cross section image of each membrane produced were obtained by scanning electron microscopy (SEM) to explain the results obtained. The results revealed that the ratio of acetic acid/PEG is the significant factor that affects urea clearance performance. The amount of the distilled water was an insignificant factor to urea clearance performance, but its presence is vital in the membrane formulation. Dialysis membranes consist of acetic acid/PEG ratio of 16.5 gives the best urea clearance performance of 40.37 %. Among the additives used, PEG 200 shows the highest clearance rate of urea. When a triple layer continuous dialysis system was used to test the membranes and it was found that the performance was increase by 25-50 %. Dialysis membranes consisting of lower molecular additives gives higher molecular clearance cut off efficiency. Final stage experiments using human blood revealed that dialysis membranes produced were comparable to the commercialized membranes with urea clearance of 60-70 %