Electrospun poly(vinylidene fluoride)-cellulose acetate-silica (PVDF-CA/SIO2) membrane for filtration application Mohamad Haziq Bin Alias

Faculty of Industrial Sciences and Technology

Thesis (Master of Science in Industrial Chemistry) -- Universiti Malaysia Pahang – 2024

Includes bibliographical references

Oil spillage and generation of industrial water-organic solvent wastewater mixture create a focus on filtration technology, which could be overcome using filtration technology. One of the most common and reliable techniques is by using membrane filtration, such as reverse osmosis, nanofiltration, and ultrafiltration. Electrospinning provides a versatile route in producing tunable diameter and pore for nanofibre filtration in recent membrane development protocols. In this work, poly(vinylidene fluoride) (PVDF) and cellulose acetate (CA) electrospun membranes were prepared at different ratios for water-organic solvent filtration application. The membranes were fabricated using needle and needleless electrospinning methods. The initial polymeric solutions were characterized using a viscometer and conductivity analysis, and the fabricated electrospun membranes were characterized using Fourier transform infrared (FTIR) spectroscopy, contact angle analysis, thermogravimetric analysis, scanning electron microscopy, tensile testing, and water filtration testing. Then, the best-performing membrane was selected to undergo silica (SiO2) modification to enhance filtration properties. The FTIR results showed the presence of β-phase in the membrane with PVDF in the polymer. The TGA thermograms showed thermal stability shifting by increasing the ratio of PVDF in the fabricated membrane. The tensile testing also showed increasing mechanical properties with the increasing ratio of PVDF in the membrane with M1 and S1 (both composed of 100% PVDF) having the highest tensile strength for needleless and needle electrospun membranes, respectively. Needleless electrospinning enhanced the tensile, mechanical, and thermal properties of the fabricated membrane as the characterization showed shifting in tensile and thermal properties. There was no trend for oil recovery in water-organic solvent filtration testing. However, S4 (50:50 PVDF to CA) demonstrated the highest flux compared to other membranes in both needle and needleless electrospinning methods with the flux value of 23,762 L·m-2 ·h -1 in 1-bromobutane as oil in water-oil mixture. SiO2 modification of S4 enhanced thermal and mechanical properties as the graph showed shifting. The flux for SiO2-modified electrospun membrane increased in T2 (S4 + 0.9% SiO2), but there was no significant trend for recovery percentage. The flux decreased in the overall trend as fouling occurred during filtration testing for repeatability testing. Overall, T2 has the best membrane properties to be applied in water-oil filtration technology with the highest flux of 41,739 L·m-2 ·h -1 with a constant rate of recovery (93–98.5%), good mechanical properties (5.62 MPa of maximum stress, 13% of maximum strain, and 0.707 MPa of Young's modulus), and good thermal properties.