To Recycle Calcium Fluoride Sludge for Mitigating Air Pollutant of a Semiconductor Fab

• Main Authors: Ching-Yang Kao, 高慶揚
• Other Authors: 張陸滿
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/tzmj7h

博士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Generation of chemical wastes in semiconductor factories is inevitable. Nowadays, the circumstance of recycling chimcal wastes as reusable resources is increasing as time goes on. It becomes more urgent and more important to reduce the chemical wastes as well as mitigating the potential environment pollution generated from the wastes. However, if one could take the waste generated from the production activities of the factory and recycle it as reusable resourse use, it could not only reduce the waste but also may cut down the energy consuming. To explore the potentials, a research project was conducted to recycle the filtering waste into the usable material for processing exhaust air. In this research, the calcium fluoride sludge waste was recycled through designated selective mesoporous materials and catalysts. The sludge was generated from a wastewater plant of a semiconductor factory. The newly fabricated materials were placed in the front of Zeolite Rotor Concentrator to absorb HMDS(Hexamethyldisilazane), and the catalysts was installed inside the VOCs(Volatile Organic Compounds, VOCs）incinerator, such as RCO (Regenerative Catalytic Oxidizers) or RTO (Regenerative Thermal Oxidizers) to reduce energy consuming. To assure their suitability before use, the new made materials must be properly tested. The most common mesoporous material MCM-41 was used as the comparison standard. And then, their physicochemical properties of the new materials were compared. A simulation device for HMDS was set and VOCs absorption efficiency experiment was performed. The selective nanometer-sized porous material was made by Sol-gel solution. The mew made material contains CaF2, therefore is called “CF-MCM”. It would be used to specifically adsorb HMDS. Moreover, in the process of preparing CF-MCM, Iron nitrate nonhydrate(Fe(NO3)3·9H2O) was added and it became a catalyst, which is referred to as Fe-CF-MCM. It was used as a catalyst in the VOCs incinerator, which not only reduced the combustion temperature of the incinerator, but also enhanced the VOCs cracking effect. CF-MCM materials need to have physicochemical properties of porous, high specific surface area and uniform pore size distribution, and also have good ability to adsorb high-boiling VOCs such as HMDS. Since the Fe-CF-MCM catalyst is also a porous material, it is also necessary to examine its characteristics and conduct a life test to examine its usability. The research results demonstrate that the long-term troubles of air filtration waste can be resolved. It not only reduces the waste, but also, it may lower the maintenance loading of VOCs treatment system and decrease the usage of energy.