FABRICATION OF POLYACRYLONITRILE NANOFIBER MEMBRANES FUNCTIONALIZED WITH METAL ORGANIC FRAMEWORK FOR CO_2 CAPTURING

摘要

Crystalline particles known as Metal Organic Frameworks (MOF's) are known for their large surface area and high adsorption and storage capacity for CO_2 gas. Electrospun nanofibers are considered as ideal substrates for synthesizing the MOF particles on the fiber surface. In this project, Polyacrylonitrile (PAN) and a Cu-based MOF known as HKUST-1 were selected as substrate fibers and adsorbent particles respectively. A precursor solution of PAN polymer hybridized with HKUST-1 particles dissolved in Dimehtylformamide (DMF) is used as the primary component solution for electrospinning. SEM images of the electrospun fibers showed small MOF particles formation into the fiber structure. A secondary solvothermal process of MOF particles growing on the fibers was then executed to increase the amount of MOF particles for effectual gas adsorption. The secondary process consists of multiple growth cycles and SEM images showed uniform distribution of porous MOF particles of 2-3 μm in size on the fiber surface. EDS report of the fiber confirmed the presence of MOF particles through identification of characteristic Copper elemental peaks of HKUST-1. Thermogravitmetric analysis (TGA) of HKUST-1 doped PAN fiber displayed 32% of total weight loss between 180°C and 350°C thus proving the as-synthesized MOF particles are thermally stable within the mentioned temperature range. A comparative IR spectroscopic result between the gas-treated and gas-untreated fiber samples showed the presence of characteristic peak in the vicinity of 2300 and 2400cm~(-1) which corroborates the assertion of adsorption of CO_2 on the system. Further step involved is to investigate the gas adsorption capacity of the filter system in an experimental test bench. Non-dispersive Infrared (NDIR) CO_2 sensors will be used at the gas inlet and outlet parts to measure the concentration of CO_2 and determine the amount of gas uptake by the filter system.