INVESTIGATION OF FUNCTIONALIZED POLYVINYLIDENE FLUORIDE/MORDENITE HYBRID MEMBRANES FOR MICROFILTRATION OF TEXTILE DYES

• Main Author: Umam, Khairul
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80734
• Institution: Institut Teknologi Bandung

One of the industries that consumes much water and produces waste is the textile industry. The development of waste processing methods continues to be carried out, and one of them is using membrane technology. The membrane material currently receiving much attention is polyvinylidene fluoride (PVDF) because it has good chemical, thermal and mechanical stability properties. PVDF is a hydrophobic polymer which often causes blockages on the membrane surface. Mixing with hydrophilic particles to become a hybrid membrane is a simple modification method that can improve membrane filtration performance, thermal and mechanical properties and resistance to blockage. Mordenite (MOR) is a type of zeolite widely available in Indonesia which has the potential as a filler in PVDF membranes for filtration of textile dyes. Previous research using the natural zeolite clinoptilolite in hybrid membranes can improve filtration performance against reactive dyes and increase resistance to fouling. Mordenite, a type of natural zeolite, can become a filler in hybrid membranes because its availability is relatively high in Indonesia. Furthermore, there is still a lack of research using mordenite in membrane applications. However, differences in polarity with PVDF can result in the formation of interface voids and low compatibility between mordenite and PVDF. Therefore, modifications on the mordenite surface are needed to bridge the interaction between mordenite and PVDF. Based on the chemical structure, organosilane compounds are expected to overcome this problem. Literature studies show that the investigations on the effects of organosilane compounds on the hybrid membrane performances are still limited. Therefore, the objective of this research is to study the effects of organosilane compounds for mordenite modification in hybrid membranes on the characteristics and performance of the membrane in filtration of textile dyes. Three types of organosilane compounds were used in these experiments, namely 3-aminopropyl triethoxysilane (APTES), 3-ethylenediaminopropyl-trimethoxysilane (EDAPTMS), and 3-mercapto-propyl-trimethoxysilane (MPTMS). The dyes for the filtration process were limited to those which are often used in the colouring process of cellulose fibers, namely Congo red (CR), reactive yellow 145 (RY 145) and indigo dyes. Modification of mordenite was carried out in toluene with a weight ratio of mordenite:organosilane of 1:2. The PVDF hybrid membranes were prepared using the phase inversion method with mordenite and MOR-organosilane concentrations of 0.75% w/w. The hybrid membranes were characterized using ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy) and XRD (Xray diffraction), thermal properties using TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry), hydrophilicity properties using contact angle measurements, morphology using SEM (scanning electron microscope), topography using AFM (atomic force microscope), mechanical properties using tensile tests and membrane filtration performance on textile dyes using the deadend filtration method. The results show that the modifications of mordenite with organosilane compounds consisting of APTES, EDAPTMS and MPTMS have been successfully carried out. It was validated by infrared spectroscopy on modified mordenite with the appearance of new peaks at 1314 cm -1 , 1490 cm-1 , 1585 cm-1 and 2933 cm-1 . The modification of mordenite with APTES and MPTMS was also observed by a decrease of weight loss in TGA analysis, which indicates that there are fewer free -OH groups in mordenite due to interaction with organosilane. The modification of mordenite with EDAPTMS was characterized by the occurrence of two stages of weight losses, which indicates the gradual organic volatilization of the EDAPTMS compound in MOR-EDAPTMS. PVDF hybrid membranes in the form of PVDF/MOR (PM), PVDF/MOR-APTES (PMA), PVDF/MOR-EDAPTMS (PME), and PVDF/MOR-MPTMS (PMM) have been made using the phase inversion method. The addition of mordenite and MORorganosilane increased the ? phase fraction of PVDF with a total fraction of 53.66%, with the highest increase in the ? phase fraction in MOR-MPTMS added with a total fraction of 57.18%. The hydrophilicity of the membrane increases as the ? phase increases in the membrane, with the PMM membrane being the most hydrophilic, which is indicated by the lowest surface contact angle. PME membranes produce the highest porosity, average pore radius and membrane swelling compared to PM, PMA and PMM hybrid membranes. Morphological analysis shows that all hybrid membranes have an asymmetric membrane structure with finger-like macropores, except PME, which has a round macropore structure and is larger than the other hybrid membranes. The distribution of MOREDAPTMS on the inside of the hybrid membrane is more homogeneous than that of other membranes, which have agglomeration in several areas of the membrane, indicating increased compatibility with the PME membrane. The addition of MORorganosilane causes improved compatibility between mordenite and PVDF, thereby increasing the mechanical strength of PMA and PMM, and even though PME has large macropores, it still has the same mechanical strength as PVDF. The increase in compatibility has also increased the thermal stability of the hybrid membrane, as indicated by the weight loss of all hybrid membranes, which is lower than the PVDF membrane. The addition of mordenite and MOR-organosilane changed the topographic characteristics of the hybrid membrane to be rougher than the topography of the PVDF membrane. All hybrid membranes have filtration performance against CR and indigo textile dyes with rejection values higher than 99%. The selectivity of PM membrane towards RY 145 decreased due to low compatibility between mordenite and PVDF. In comparison with PVDF membranes, the selectivity and permeability towards RY 145 in PMA and PMM membranes were increased, which indicated a better interaction of mordenite with PVDF. A remarkable performance was achieved by the PME membrane, which has a relative same as PVDF membranes selectivity but the highest permeability, twice as much as PVDF membranes. It showed that good interaction and compatibility existed between mordenite and PVDF. Moreover, the addition of mordenite and MOR-organosilane as polar particles has also increased the fouling resistance properties of the membrane due to a combination of changes in roughness characteristics and increased membrane hydrophilicity. It can be concluded that the hybrid membrane with the best performance was obtained by the PME membranes using MOR-EDAPTMS. This membrane showed a good selectivity for CR, RY 145 and indigo dyes, a permeability that increased twice as much as PVDF membrane, high thermal resistance and good fouling resistance properties.