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2025 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 1026, article id 180476Article in journal (Refereed) Published
Abstract [en]
Extraction of 90Sr from groundwaters is of great significance in energy and ecological environment. Phosphate minerals have been proposed as a suitable matrix for the in-situ remediation of radionuclides from groundwaters by encouraging co-precipitation. However, the understanding of how Sr2+ precipitate into phosphate minerals affected by grain growth has not been fully resolved. In this work, the precipitation reaction of Sr5(PO4)3OH and SrHPO4 were studied based on experiments and PHREEQC simulation. Some specific issues such as the precipitation reaction kinetics and the phase evolution during grain growth were discussed in detail, along with investigating the chemical stability of obtained precipitations before and after calcination. The results show that pH appears to be a prevailing factor with a recommended pH = 8 ∼ 11 to obtain the stability domain of Sr5(PO4)3OH and SrHPO4 to remove Sr2+ with a removal rate over 98 %. Interestingly, SrHPO4 is more likely to preferentially nucleate at pH = 8 solution compared to Sr5(PO4)3OH, and the poorly crystalline SrHPO4 tends to disappear over time. TEM and SAXS results show the plate-like nanoparticles of SrHPO4 are wrapped into the rod-like particles of Sr5(PO4)3OH during the grain growth, and the inner SrHPO4 can react with Sr5(PO4)3OH to form Sr3(PO4)2 at temperature over 600 ℃. This observation is inconsistent with the previous grain growth result of poorly crystalline SrHPO4, where it is believed to recrystallize into more stable Sr5(PO4)3OH crystals over time. Moreover, the Sr-O binding energy plays an important role in controlling the degradation of Sr5(PO4)3OH, Sr3(PO4)2, SrHPO4 and β-Sr2P2O7.
Place, publisher, year, edition, pages
Elsevier, 2025
Keywords
Sr5(PO4)3OH, SrHPO4, Grain growth, Precipitation, Stability
National Category
Metallurgy and Metallic Materials Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-556066 (URN)10.1016/j.jallcom.2025.180476 (DOI)001476575400001 ()2-s2.0-105002767753 (Scopus ID)
2025-05-092025-05-092025-05-09Bibliographically approved