Preparation of Polystyrene Particles/Polymer Mixed Matrix Membranes and Their Application in Gas Separation

• Main Authors: Ming-Hung Lin, 林銘鴻
• Other Authors: 孫幸宜
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2x86uc

碩士 === 國立中興大學 === 化學工程學系所 === 106 === This study focused on the preparation of polystyrene/sodium alginate mixed matrix membranes using particulate template method. Polystyrene particles of uniform size (200, 400, and 600 nm) were used as the templates. Via Langmuir-Blodgett film technique, the particulate templates were self-assembled on an ITO glass and aligned in multiple rows. The hexagonal close-packed arrangement of the polystyrene particles was confirmed by SEM. An appropriate amount of 5 wt% sodium alginate aqueous solution was then injected into the voids between the particulate templates by spin coating at 900 rpm. A dense film was casted with the solvent being evaporated at 45°C for 3 h. By detaching it from the glass plate using methanol as non-solvent, followed by drying at room temperature for 1 h, a mixed matrix membrane with polystyrene particles incorporated was created. In this way, two materials with distinct properties, polystyrene (MW =34300 , Tg = 95°C, contact angle = 110±7) and sodium alginate (MW = 110000, Tg = 22°C, contact angle = 41±2), could co-exist within a single membrane. In a membrane with 5 layers of 400 nm polystyrene particles, the thickness was 2 m and the volume ratio of polystyrene/sodium alginate was 74/26. When applying it in the process of gas separation with a 200 m-thick porous membrane as the support, the CO2 permeability was 235.6 barrer and the ideal selectivities for CO2/CH4 and CO2/N2 were 5.36 and 9.1, respectively. In comparison with the performance for pure polymer membranes (polystyrene: CO2 permeability = 9.1 barrer, CO2/CH4 selectivity = 16.4, CO2/N2 selectivity = 22.6; sodium alginate: CO2 permeability = 372.7 barrer, CO2/CH4 selectivity = 2.9, CO2/N2 selectivity = 5.4), it shows that the gas permeation through polystyrene/sodium alginate mixed matrix membrane was dominated by the material with lower resistance (sodium alginate) although this material had minor amount. Then we used the same method to produce the polystyrene/cellulose acetate mixed matrix membrane. Gas permeation results biased towards pure polystyrene data. On the other hand, we use SIO2 instead of PS particles, after filling in CA polymer, etching SIO2 particles, and finally filling in PS polymer, also made PS/CA MMM. However, the proportion of air inside this film is high, so its permeability is about 1 times higher than the film in this study. From Robeson’s upper bounds, the Permeability of PS/SA MMM is higher than that of general glassy polymers. And selectivity is 49% more than SA data.