Preparation and Characterization of Composite Membranes of Polysulfone-Poly(methylmethacrylate)-Polyamide for Starch and Maltose Separation

• Main Author: RADITYA TANARDI (NIM 10505070), CATHERINE
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/11933
• Institution: Institut Teknologi Bandung

Conversion of starch, an abundant natural resource in Indonesia, into oligosaccharides is one of the alternatives that should be done in order to increase its economical value. Membrane technology could be used for enzymatic conversion of starch, because membrane shows a high selectivity towards different size of various molecules. The objective of this research is to prepare composite membrane which can separate starch and maltose as one of the starch conversion products. Composite membrane was chosen due to its interesting combination of high permselectivity and permeability. In this research, the supporting layer was made by phase inversion technique from a blend of poly(methylmethacrylate) (PMMA) and polysulfone (PSf), using poly(ethyleneglycol) (PEG) as additive and a mixture of N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc) as solvent. The selective layer was constructed by reacting m-phenylenediamine (MPD) and trimesoylchloride (TMC) on the surface of the supporting layer by interfacial polymerization. The results showed that the membrane being prepared from a dope with composition of PMMA: PSf: PEG: DMF: DMAc (% w/w) = 4: 8: 12: 25.5: 50.5 could be used as the supporting layer. Various characterizations of the resulting membranes were conducted, including permeability (measured as flux), permselectivity (measured as rejection coefficient), degree of swelling, contact angle and observation of membrane morphology by Scanning Electron Microscope (SEM). Using a relatively high operational pressure (5 bars), the composite membrane remained having a high rejection coefficient. It was observed a decrease in degree of swelling of composite membrane, i.e. 236.84%, relative to supporting layer, 251.48%. This might be an indication of the presence of crosslinked polyamide layer, covering the pores of support layer. The decrease in contact angle was demonstrated: 134o for the supporting layer and 87o for the composite membrane. This could be an apparent proof that polyamide layer as composite layer adding hydrophilic properties to the supporting layer. Morphology of the membrane surface, revealed by SEM, showed that a new material has been coated on supporting membrane. Being compared to the composite membrane, the rejection of the supporting membrane towards starch decreased, from 93.81% to 85.78%. On the other hand, the rejection of both membranes towards maltose showed a tendency to remain the same. In the meantime, the increase in flux of both membranes towards a mixture of starch and maltose is very significant: a multiplication by 9.2. The flux of the supporting membrane was 0.9 L m-2 h-1 while that of the composite membrane was 8.4 L m-2 h-1. <br />