ELECTROSPUN ZR MOFS/PVDF COMPOSITE MEMBRANE FOR BORON COMPOUND FILTRATION

• Main Author: Fajri Octavianti, Resti
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/82931
• Institution: Institut Teknologi Bandung

Boron compounds are essential micronutrients for plants, humans, and animals. However, a slightly higher composition of boron than required can make it toxic. Most countries worldwide have set the concentration of boron in drinking water to be below 0.5 mg/L. In water, most boron compounds exist in the form of B(OH)3 or B(OH)4¯. One approach to separating boron compounds in water can be carried out using a PVDF membrane composited with Zr-based Metal-Organic Frameworks (MOFs), specifically UiO-66. Additionally, enhancing the hydrophilic properties of the membrane can be achieved by modifying the functional groups on the MOF organic ligands, thereby improving the membrane's performance in rejecting boron compounds in water. In this study, UiO-66 MOFs (U) were modified by replacing terephthalic acid ligands with 2-aminoterephthalic acid ligands, which have amine groups (UN), and 2,5-dihydroxyterephthalic acid ligands, which have hydroxyl groups (UO). These were then composited with polyvinylidene difluoride (PVDF) polymer to create boron filtering membranes. The MOF and PVDF polymer (P) composites were fabricated using the electrospinning method to produce composite membranes with higher solution flux and boron compound rejection compared to the phase inversion method. X-Ray Diffraction (XRD) characterization confirmed that the crystal structure of the MOFs matched the reference, with characteristic peaks at 2? = 7.37°; 8.51°; and 25.74°. Additionally, the modification of MOF ligand functional groups was characterized using Fourier Transform Infra-Red (FTIR), revealing distinct peaks at 3460 and 3350 cm-1 for UN MOFs and at 3240 cm-1 for UO MOFs. The fabricated composite membranes were characterized using Scanning Electron Microscopy (SEM) to examine the morphology and cross-section. The analysis showed that the surfaces of P and P-UN membranes had denser pores compared to P-U, as well as Energy Dispersive Spectroscopy (EDS) to confirm the uniform distribution of MOFs on the membrane. The contact angle measurements indicated a decrease from membrane P, P-U, and P-UN, which were 82.1°, 80.3°, and 66.5°, respectively. Additionally, the boron concentration in the filtrate was determined using UV-Vis spectrophotometry. The flux obtained from the electrospun membranes showed a significant increase compared to the flux from the phase inversion membranes. The rejection of boron compounds from the electrospun membranes also followed the same trend as the phase inversion membranes; as the hydrophilicity of the membrane increased (P-UN > P-U > P), the rejection percentage also increased. However, the boron rejection percentage from the electrospun membranes was still slightly lower than that of the phase inversion membranes.