PMMA-ZEOLITE 4A COMPOSITES NANOFIBERS AS FUNCTIONAL MATERIAL FOR ADSROPTION OF NI2+, CD2+ DAN ZN2+ IONS

• Main Author: Tri Suryandari, Ervin
• Format: Dissertations
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/46597
• Institution: Institut Teknologi Bandung

Contamination of heavy metal ions into water bodies is a critical problesm. Eventhought some elements in trace amounts are essential for humans, plants and animals, but at certain concentrations it can be toxic to all living things. Especially the availability of heavy metal ions in the water can be derivated from automotive industries, batteries, tanning & metal coating prosesses. Therefore, it is necessary to create an effective strategy for removing heavy metal ions from waters, because at high concentrations it can undergo transformation into more toxic compounds. The adsorption is one of favorable methods for removal contaminant from water since it is high efficiency, easy handling, can be reused, inexpensive and provides alternatives of adsorbents, materials that have high selectivity and sensitivity. Currently, nanofiber has atracted great attention due to its potential advantages in various application. It is exhibit surface area (on the nm2 scale), superior mechanical performance such as stiffness and tensile strength, high porosity, small pore size, light weight & high permeability. These properties lead nanofiber to be widely used as an adsorbent for removal heavy metal ions. Electrospinning method is one of the simplest ways to form nano-sized fibers. The modification of nanofiber was carried out by combining the polymer with zeolite to form a composite which is a functional material that has favorable characteristics (high thermal stability, recyclable & dispersable) . Functional material development begins by preparing PMMA nanofiber and PMMA- Zeolite nanofiber composites by electrospinning techniques with optimization conditions including variations in polymer concentration, needle tip distance to the collector, applied electric voltage and polymer flow rate. The synthesized this nanofiber was characterized by infrared spectrophotometry (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), thermogravimetry (TGA), N2 adsorption at 77 K, and contact angle measurement. The adsorption study was conducted at optimized parameters i.e time contact, adsorbent mass and adsorbate concentration.The performance of nanofiber composite PMMA-Zeolite adsorbent was studied by batch adsorption for removal heavy metal ions i.e Ni2+, Zn2+ and Cd2+, whereas the determination of the adsorbed of metal ions is carried out by atomic absorption spectrophotometry (AAS) The results showed that the optimum conditions for PMMA nanofiber synthesis were obtained at a concentration of 22.5% (w/v), an electric voltage of 20 kV, the distance of the needle to the colecttor 15 cm and a polymer flow rate of 0.004 mL/minutes. The PMMA-Zeolite composite nanofiber was successfully synthetized with the addition of the optimum zeolite was 40%. Composite nanofiber PMMA-Zeolite 40%. From FTIR data shows wave number 3446.79; 1149.02; 754.17 and 464.84 cm-1 in the PMMA-Zeolite nanofibers spectrum which indicate the typical spectra of zeolites. In addition, there has also been a shift in wave numbers due to the interaction of hydrogen bonds formed between zeolites and PMMA. This is consistent with the TGA results that the addition of zeolites will increase the thermal stability of the nanofiber PMMA-Zeolite. The addition of zeolites to PMMA nanofibers will change some of the characteristics of nanofibers, changing the nature of PMMA nanofibers that hydrophobic turn into hydrophiles, this can be seen from the decrease in the contact angle of nanofibers to water with the increasing number of zeolites, this is supported by hydration free energy (?GSW) data, indicating that the surface of nanofibers increasingly interacts with water. The addition of zeolite also increased specific surface area which was shown from the BET data, 26,165 m2g-1 for PMMA nanofiber and 26,988 m2g-1 for PMMA-Zeolite composite nanofibers. From SEM mapping and TEM imagery it was proven that zeolites managed to spread evenly on the surface and inside the nanofibers. Optimum adsorption conditions were obtained at pH 6 for adsorption of Ni2+, Cd2+, Zn2+ ions for zeolites and PMMA-Zeolites nanofibers. This corresponds to the zeta potential which has the most negative charge at pH 6. The optimum contact time is 180 minutes for zeolites, 240 minutes and 300 minutes for nanofiber PMMA and nanofiber PMMA-Zeolites. The adsorption isotherm model follows the Freundlich isotherm model and the adsorption kinetics follows the second-order pseudo-model. Based on the intraparticle diffusion model the adsorption mechanism occurs in two stages and the diffusion rate is controlled by the two stages namely film diffusion and intraparticle diffusion shows the occurrence of chemisorption and occurs in a multilayer. Based on the adsorption thermodynamic parameters, it can be stated that the adsorption process occurs spontaneously and is endothermic. PMMA-Zeolite composite nanofibers provide better adsorption performance of 70.2358%; 86.6529% and 88.9463% for Ni2+, Cd2+ and Zn2+ metal ions while for zeolites 68.2185%, 85.4222% and 88.66563%. PMMA-Zeolite composite nanofibers provide more resistance to acids than zeolites.