MODIFICATION OF PVDF MEMBRANE USING UIO-66 DERIVATIVES AS BORON REJECTION MEMBRANE

• Main Author: Suryadi, Martin
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/64669
• Institution: Institut Teknologi Bandung

Boron is one of the contaminants found in water and can be found in natural water sources, but in seawater the concentration far exceeds the specified limit, which is around 7 mg/liter, even in certain areas it can be higher. This high boron concentration must be reduced so that it reaches a predetermined standard, WHO sets a standard for a maximum boron level of 0.5 mg/liter in drinking water and this is also in accordance with PerMenKes 492 of 2010 concerning Drinking Water Quality Requirements. Meanwhile, in the use of water for irrigation, the boron threshold can be different because plants can have different sensitivities. Boron in water is in the form of boric acid (B(OH)3), but because of its small size and neutral charge it will be difficult to filter or separate. Filtering to reduce boron levels in water has been previously investigated using adsorption methods, ion exchange resins, membrane filtration, and others. Filtration using polymer-based membranes is one of the most commonly used methods due to its ease of fabrication and modification, as well as its good filtering ability towards another. However, to filter boron under ideal conditions there are still challenges to be faced. Metal-organic frameworks (MOF) are porous materials which research is growing rapidly due to the wide application of these materials. MOF has several advantages such as: high surface area and also functionality that can be modified. Zr-based MOF UiO-66 is one of the materials that can be used to combine with membranes to filter boron. The metal center Zr and the benzene ring area of UiO-66 have been investigated and shown to be active sites in the formation of interactions with boron. The active group in MOF can be modified to support its application as a boron repellent material by adding negatively charged groups such as amine groups and dihydroxy groups. These two groups are known to be groups that can help in the boron rejection process because of their good interaction with boron. In this study, Zr-based MOF which was functionalized with two functional groups namely amine and dihydroxy was then added to the PVDF membrane. The synthesized MOFs were characterized using XRD (X- Ray Diffraction) to see the crystal structure formed and FTIR to see the functional groups resulting from the modification. PVDF was chosen as a composite membrane base because of its resistance to chemicals, pH and temperature. The combined membranes that have been fabricated were characterized using SEM (Scanning Electron Microscopy) to see the morphology and also the cross-section of the membrane. The performance of the membrane that has been combined with MOF was tested using a microfiltration device. Determination of boron concentration was determined by colorimetry using a UV-VIS instrument by utilizing the reaction between boric acid and curcumin which shows absorbance at a wavelength of 540 nm. The hydrophilicity of the membrane was also tested by measuring the contact angle between the water droplets and the membrane surface. The addition of MOF to PVDF causes the membrane to become hydrophilic which is indicated by the reduced contact angle of the membrane. The best membrane flux of 54 liters/m2.hour was shown by the membrane that had been added with UiO-66 without any modification process. The best rejection of boron by 53% was shown by the membrane that had been added with UiO-66 which had previously been modified by adding a dihydroxy group. The combination of MOF UiO-66 with UiO-66 which has been modified with a dihydroxy group has been carried out and the dominant nature of the dihydroxy group is shown from the results oftheflux and membrane rejection.