Preparation Of Hydroxyapatite And Its Immobilization Performance Of Uranyl Ions

Uranium has been a crucial strategic resource for major nuclear fuels,defense,military and power sources.Under the background of increasing global energy shortage,positive development of safe nuclear power becomes one of the important strategies for the nuclear power industry development.In particular,in the 13th Five-year Plan of China's Strategic New Industrial Development Plan,it is pointed out that China's nuclear power construction is entering a new era.Undoubtedly,these measures will promote the increasing demand for uranium resources.And at the same time,uranium mining,metallurgy,purification and tailings treatment and disposal will inevitably pollute the soil and water body of the site.Effective prevention and control of uranium pollution,slowing down its migration in the ecological environment,and effectively avoiding the threat to life and health of human beings have aroused wide public concern.In this work,biological hydroxyapatite materials were successfully prepared by solid phase-calcining method using waste phosphorus-rich wasted fish bone as the raw material by adjusting the technological parameters.Nano-sized granular hydroxyapatite Bio-HAP₆₀₀material with good crystallinity and excellent performance was obtained by means of XRD,SEM,BET and FTIR analysis and characterization.And the performance of removing uranyl ion by Bio-HAP₆₀₀ was investigated by sequential batch static experiment,by taking Bio-HAP₆₀₀ as the decontamination agent and the simulating uranium-containing wastewater in laboratory as the treatment object,compared with a kind of nano-hydroxyapatite material Nano-HAP purchased from commercial products.The results showed that Bio-HAP₆₀₀ has significant uranium fixation removal capacity,and the removal amount of 10 min exposed to UO₂²⁺is comparative to that of Nano-HAP.The maximum removal capacity of 384.56 mg/g in the experimental range showed obvious potential advantages in the actual uranium fixation.Besides,the interaction process and behavior mechanism of Bio-HAP₆₀₀ and UO₂²⁺are deeply studied by means of microscopic phase analysis and macroscopic theoretical calculation.And the practical application test was held in actual uranium contaminated soil and water samples.Specifically:1)Good crystallinity hydroxyapatite Bio-HAP₆₀₀ was obtained from the wasted fish bones by adjusting the calcination parameters,with the specific surface area of 74.43m²/g and uniform distribution of the nano-particles.2)Removal of uranyl ions by Bio-HAP₆₀₀ was tested by laboratory simulation of uranium-containing wastewater.The results showed that Bio-HAP₆₀₀ had the remarkable uranium fixation removal capacity,and the removal amount of UO₂²⁺in was similar to that of Nano-HAP with the maximum removal capacity of 384.56 mg/g.3)Phase migration and transformation of uranium in mineralized immobilization by wasted bio-hydroxyapatite was analyzed.It was found that the solid phase metallogeny existed in the process of interaction.The Ca?UO₂?₂?PO₄?₂?H₂O?₆ nano-square sheet of phosphate-uranyl phosphate mineral was formed in the contact process.It is suggested that the main reaction mechanism of UO₂²⁺fixation with Bio-HAP₆₀₀ is based on the dissolution-chemical mineralization.4)Macroscopic theoretical calculation and software simulation on the interaction process and behavior of Bio-HAP₆₀₀ and UO₂²⁺show that PO₄^3-plays a primary role in uranyl fixation and participates in the formation of the meta-autunite,and Ca²⁺ions take effects by ion exchange in the fixed removal.With the aid of geochemical simulation software PHREEQC and Visual MINTEQ+v 4.6,the relationship between phosphate and uranyl ion under different P/U ratio was analyzed and simulated.The results show that the phosphate ion and uranyl ion are combined according to the ratio of 1:1.5)Practical application test was held in actual uranium contaminated soil and water samples.The addition of Bio-HAP₆₀₀ can obviously reduce the level of uranium leakage in soil in a short period of time,and delay the release of uranium in contaminated soil under acidic conditions.The poor long-term stability still needs to be further improved and promoted.Also,Bio-HAP₆₀₀ still has high removal efficiency for uranium polluted water under complex components,and has synergistic effect on other heavy metal ions.