2017 Volume 88 Issue 3 Pages 221-227
In this study, we examined the relationship between powder properties of ill-crystallized calcium silicate hydrates (C-S-H) synthesized by various methods and the recovery rate of phosphorus (P) from an aqueous solution using C-S-H. The calcium (Ca) ion of C-S-H reacted with P in the aqueous solution and all recovered materials contained hydroxyapatite. P recovery using C-S-H was completed within 30 min and each C-S-H showed a different Ca reaction rate and P-recovery rate. Most of the recovered materials contained no less than 15％ citric-soluble phosphates.
Our research verified that the Ca reaction rate of C-S-H has a strong negative correlation to C-S-H crystallite size estimated by X-ray diffraction. However, the Ca reaction rate did not correlate with other powder properties, such as average particle diameter, specific surface area, and bulk density. Because of a strong correlation between the Ca reaction rate and P-recovery rate, C-S-H crystallite size also has a strong negative correlation to the P-recovery rate. In conclusion, P-recovery rate increased with the decrease in C-S-H crystallite size.
