Optimization of Process Parameters for the Preparation of CaO/CaSO₄/Coal Fly Ash Sorbent for Sulfur Dioxide (SO₂) Removal: Part II

Abstract

A two-step optimization strategy was employed to optimize the surface area of sorbent prepared from coal fly ash, calcium oxide (CaO) and calcium sulfate (CaSO₄) for flue gas desulfurization. In the first step, a 3 level full factorial design of experiment was used to develop a regression model equation to correlate the significant experimental sorbent preparation variables to the surface area of the resulting sorbent. The three experimental sorbent preparation variables studied are hydration period (x ₁), ratio of CaO to fly ash (x ₂) and amount of CaSO₄ (x ₃). In the subsequent step, response surface methodology was used to identify the experimental sorbent preparation variables that maximize the surface area of the sorbent. Through this two-step optimization strategy, it was found that at a hydration period of 10 hrs and drying temperature of 100°C, optimum surface area of 67.0 m²/g could be attained by using 5 grams of CaO, 13.7 grams of fly ash, and 7.4 grams of CaSO₄ in the preparation mixture. The prediction was verified with experimental runs.

Keywords:

• coal fly ash sorbent
• design of experiment
• desulfurization
• optimization
• response surface methodology

Acknowledgments

The authors would like to thank ASEAN University Network/Southeast Asia Engineering Education Development Network (AUN/SEED-Net), JSPS-VCC (Program on Environmental Science, Engineering and Ethics), Ministry of Science, Technology and Environment Malaysia (Project No. 08-02-05-2040EA001), and Universiti Sains Malaysia (USM short term grant) for the funding and support on this project.