Hydrothermal removal of Sr2+ in aqueous solution via formation of Sr-substituted hydroxyapatite.
We removed Sr(2+) in simulating wastewater and simultaneously prepared Sr-substituted hydroxyapatite via chemical precipitation and hydrothermal treatment. Both higher initial pH value and higher molar ratio of Sr/(Sr+Ca) contributed to lower residual Sr(2+) concentration and higher removal efficiency. About two thirds of Sr(2+) residual in solution after chemical precipitation were further reduced by hydrothermal treatment. The optimal Sr removal result was 99.66% with an ultimate concentration of 2.0 mg L(-1) when the initial pH was 12 and Sr/(Sr+Ca) was 0.2. Sr-substituted hydroxyapatite phase with hexagonal structure was identified by XRD and EDS results. However, it was found that SrHPO(4) phase was formed in the samples with high Sr composition. The lattice constants became larger with the increase of Sr(2+) and the crystallinity became higher with the increase of pH value. Rod-like particles were observed in SEM images of synthesized Sr-substituted hydroxyapatite samples, with the size of 20-30 nm in width and 70-100 nm in length. With little secondary waste and simple treating procedure, this method is an effective and prospective measure to deal with (90)Sr in nuclear waste and industry wastewater.
Tan
Sheng-Heng
SH
Department of Ocean Science and Engineering, Zhejiang University, Hangzhou 310028, People's Republic of China.
Chen
Xue-Gang
XG
Ye
Ying
Y
Sun
Jie
J
Dai
Ling-Qing
LQ
Ding
Qian
Q
D000327:Adsorption; D017886:Durapatite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D011122:Polyphosphates / Q000737:chemistry; D012996:Solutions; D013324:Strontium / Q000302:isolation & purification*; D013326:Strontium Radioisotopes / Q000302:isolation & purification; D013816:Thermodynamics; D014865:Waste Disposal, Fluid; D014867:Water; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
D010710:Phosphates; D011122:Polyphosphates; D012996:Solutions; D013326:Strontium Radioisotopes; D014867:Water; D017886:Durapatite; C005692:triphosphoric acid; C018279:sodium phosphate; D013324:Strontium