Ion Exchange Capacity of Sr²⁺ onto Calcined Biological Hydroxyapatite and Implications for Use in Permeable Reactive Barriers

Abstract

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 (4001100°C) to remove the organic matter (87.1 mg·g ¹1) 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 ¹8 to 7.7 © 10 ¹8 m). There was also an observed decrease in specific surface areas (98.9 to 0.99 m 2 ·g ¹1 ) and increase in particle sizes (50 to 1000 nm). The sorption densities of Sr 2+ decreased with increasing calcination temperatures, from 0.34 to 0.05 mmol·g ¹1. However, once normalized for surface area, the sorption densities increased from 1.8 to 5.9 mmol·m ¹2 . 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 PO 4 3¹ and resulted in the precipitation of strontium phosphates, ultimately reducing the permeability of PRBs.

Bacterially Produced Calcium Phosphate Nanobiominerals: Sorption Capacity, Site Preferences, and Stability of Captured Radionuclides

“…This correlates with the removal of organics (r 2 = 0.97) leading to an increase in void spaces and a subsequent increase in SSA 15 . The SSA then decreased with increasing heat treatments to 12 ± 4 m 2 g −1 (700-BHAP), consistent with the enlargement of XRD crystallite and TEM domain sizes 25 (Figure 2, Figure 3). The organic content which is attributed to Serratia sp.…”

Biogenic Hydroxyapatite Obtained from Bone Wastes Using CO2-Assisted Pyrolysis and Its Interaction with Glyphosate: A Computational and Experimental Study

“…According to the IUPAC technical report, it is classified as a Type III isotherm, characteristic of systems with no porosity or macroporosity, with a weak interaction between N 2 and the BHap surface. The BET specific surface area was determined to be 5 m 2 ·g –1 , which is consistent with the low surface areas reported for this type of materials. , Finally, it was determined that BHap presents a basic nature because of its high pH PZC of 9.7. The basicity of this material is due to the presence of groups such as phosphates (PO 4 3– ) and carbonates (CO 3 2– ).…”

“…The BET specific surface area was determined to be 5 m 2 ·g –1 , which is consistent with the low surface areas reported for this type of materials. 35 , 36 Finally, it was determined that BHap presents a basic nature because of its high pH PZC of 9.7. The basicity of this material is due to the presence of groups such as phosphates (PO 4 3– ) and carbonates (CO 3 2– ).…”