#TITLE_ALTERNATIVE#

• Main Author: (NIM: 33014004), KHOIRUDDIN
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/28484
• Institution: Institut Teknologi Bandung

<p align="justify"> Heterogeneous ion-exchange membrane is the first commercialized charged membrane which has relatively low production cost and high mechanical strength. However, its conductivity and permselectivity (Ps) are lower than homogeneous membrane. Additive blending and chemical treatment are relatively simple <br /> <br /> modification methods which can be used to improve electrochemical properties of heterogeneous ion-exchange membrane. In this study, polyvinyl chloride (PVC)- based heterogenous ion-exchange membranes were prepared by phase inversion process. Polyethylene glycol (PEG400) was used as additive to improve membrane hydrophilicity. The prepared cation-exchange membrane was also modified by <br /> <br /> chemical treatment i.e. by immersing the membrane into sulfuric acid solution (95%-97%). Heterogeneity of membrane structure was determined by Microheterogeneous model to determine its effect on membrane characteristics. <br /> <br /> Results showed that increasing PVC polymerization degree and concentration affected Ps positively. Ps was increased from 0.85 to 0.91 when the polymerization degree was increased from 700 to 1,290. Ps was also increased from 0.85 to 0.89 when PVC concentration was increased from 10% to 15%. However, increasing PVC polymerization degree and concentration affected membrane conductivity negatively. It may be due to the change of membrane structure. The addition of PEG400 up to 10% has successfully increased membrane conductivity from 1.33±0.16 mS/cm to 2.17±0.25 mS/cm and Ps from 0.85 to 0.92. The addition of PEG400 successfully improved membrane hydrophilicity showed by a decrease in water contact angle (WCA) from 78.9o±1.4o (PEG400 0%) to 66.4o±6.0o (PEG400 10%). PEG400 also increased ion-exchange capacity (IEC) from 2.13±0.03 meq/g <br /> <br /> to 2.70±0.09 meq/g. New void fractions were formed in the membrane matrix due to the addition of PEG400. Chemical treatment of PVC membranes with PEG400 concentration of 0% (M0) and 10% (MA0) produced membranes (M1, M2, M3, MA1, MA2, MA3) with higher conductivities. Conductivity of M2 membrane was increased up to 100% (from 0.89±0.12 mS/cm to 1.83±0.22 mS/cm), while the conductivity of MA2 was increased up to 120% (from 1.22±0.03 mS/cm to 2.68±0.11 mS/cm). The chemical treatment might lead to an increase in membrane hydrophilicity and formation of new voids in the membrane due to PEG400 removal from the matrix, so Wu and conductivity of modified MA0 membranes (MA1, MA2, MA3) were higher than modified M0 membranes (M1, M2, M3). Ps was decreased in most of the modified membranes. M1 membrane (immersed in sulfuric acid for 24 h) showed the best Ps (0.95) with a relatively good conductivity (1.47±0.04 mS/cm). PEG400 (10%) also increased Wu (from 0.30±0.00 g/g to 0.33±0.02 g/g), IEC (from 0.91±0.04 to 0.99±0.09 meq/g), and conductivity (from 1.1±0.1 mS/cm to 1.7±0.2 mS/cm) of anion-exchange membrane. Hydrophilic additives (PEG400, PEG1000, and ZnO) improved anti-organic fouling property of anion-exchange membrane. During electrodialysis process of diluted peat water solution (permeate of an ultrafiltration membrane, 10 times dilution), the electrical potential change of modified anion-exchange membranes with additive (Vt/Vo) was reduced from 1.27 to 1.12-1.17 (5 minutes of operation). The additive also helped to increase conductivity recovery (km/kmo) from 0.9 to 0.95-0.98. Prepared cation-exchange <br /> <br /> membranes had relatively high heterogeneity (inter-gel phase fraction (f2) = 0,28- 0,43) and the conductive phase fraction was randomly distributed (a = 0.20-0.31). <br /> <br /> In general, an increase in f2 value resulted in higher conductivity and lower Ps. Conductivity was increased from 0.94 mS/cm to 2.33 mS/cm and Ps was decreased from 0.91 to 0.87 when the f2 was increased from 0.34 to 0.43. Within the range of membrane preparation parameters or conditions used in this study, heterogeneous cation-exchange membrane with optimum conductivity and Ps (1.47±0.04 mS/cm dan 0.95) was obtained when the membrane was prepared by using PVC polymerization degree of 1,290, PVC concentration of 10%, and PEG400 concentration of 0% which was then immersed in sulfuric acid for 24 h (at room condition). <p align="justify">