Highly reactive metakaolin: a multi-parameter optimization by response surface methodology

Abstract

Multi-parameter effect consideration during metakaolin conversion gives the best optimum processing conditions. Kaolin deposits have different properties, which makes it vital to establish optimum conditions for a distinctive kaolin deposit. The Response Surface Methodology under the Box-Behnken Design has been adopted in the current study to optimize the processing conditions for kaolin-to-metakaolin conversion. The temperature of 765 °C, the rate of 10 °C min−1, and 6.46 h of soaking were the optimum conditions for yielding the highly reactive (1382.15 mg Ca (OH)2/g) metakaolin. The kaolin sample's distinctive reflections on two theta degrees at 14.32° and 29.03° proved that kaolinite was present. However, x-ray diffraction suggested that the optimized metakaolin was lacking those reflections. The Fourier-transformation infrared spectroscopy confirmed the presence of kaolinite in the sample with wave number range at the bands 3692, 3650, and 3620 cm−1, which disappeared to form a broad band in this region, which validates the formation of reactive amorphous metakaolin.