Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Prof. Sohrab Rohani

Abstract

Coal fly ash (CFA) is a major bi-product of coal fired power plants and is a liability for coal power industry. Coal fly ash has been accumulating rapidly around the globe and has been known to be accident prone, resulting in $1.65 billion in clean-up costs and fines. Given the environmental damage CFA is capable of causing, it is a great interest for scientists to recycle this material. Utilization of novel energy such as microwave and ultrasound has been of research interest for the zeolitization of coal fly ash.

This research produced zeolites from CFA utilizing microwave and ultrasound power. Single mode microwave which significantly decreases was utilized to produce zeolite with 300 W power in 30 min. The amount of irradiation was also related to zeolite the growth of crystals and phase purity. Ultrasound assisted zeolitization resulted in single phase zeolite-A crystals with high crystallinity and smaller crystal sizes at 85°C compared to 95°C with conventional synthesis. Ultrasound probe was shown to produce the results with only 1/10th of energy as previously reported works. The Recycling of waste stream for zeolitization process was also investigated this can contribute to lower the financial costs of zeolite production. A novel design of a microwave reactor is introduced in this work that utilizes the microwave energy efficiently this design can result in cost savings in the production of zeolites through microwave energy. It is a first step in industrializing the zeolitization of CFA utilizing microwave energy which can result in a cleaner coal energy in world where it is a significant source of power generation and can offer the option of using CFA waste accumulated decreasing the likelihood of future accidents causing environmental damages and legal liabilities.

This work has shown that microwave and ultrasound irradiation can significantly decrease the time of zeolitization process. Single mode microwave has been shown to be much more effective in producing the same results at a third of the power rating for a multimode microwave. Similarly, utilization of ultrasound probe produced a single phase zeolite at a tenth of power reported using ultrasound bath. Ultrasound assisted zeolitization was observed at 85°C, about 10°C lower than conventional synthesis. Waste stream recycling was shown to be effective for a couple of runs indicating that waste from zeolitization can be reduced. A pilot scale microwave reactor with a novel design was commissioned can be utilized in future from microwave synthesis.

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