2012 Volume 53 Issue 7 Pages 1267-1272
With the recent Fukushima incident, there is an urgent need to find cost effective and workable permeable reactive barrier (PRBs) for the remediation/retardation of problematic radionuclides. Catfish bones were calcined at various temperatures (400–1100°C) to remove the organic matter (87.1 mg·g−1) and to change the structural properties of the hydroxyapatite (HAP). Increasing temperatures increased the HAP crystallinity as indicated by a decrease in lattice strain (0.0098 to 0.00135) and an increase in crystallite sizes (5.0 × 10−8 to 7.7 × 10−8 m). There was also an observed decrease in specific surface areas (98.9 to 0.99 m2·g−1) and increase in particle sizes (50 to 1000 nm). The sorption densities of Sr2+ decreased with increasing calcination temperatures, from 0.34 to 0.05 mmol·g−1. However, once normalized for surface area, the sorption densities increased from 1.8 to 5.9 mmol·m−2. Overall, this research has important implications for the design of hydroxyapatite PRBs with higher calcination temperatures producing a more reactive material with larger particle sizes for increased permeability. Lower calcination temperatures produced amorphous HAP material, which released more aqueous PO43− and resulted in the precipitation of strontium phosphates, ultimately reducing the permeability of PRBs.