Amino-triggered micro acidity promotes phosphate release from hydroxyapatite and uranium autunite formation

In order to achieve a green, efficient, and stable removal of U(VI) from the leachate of U(VI) tailings, this study employs 3-aminopropyltriethoxysilane (APTES) as a modifying agent to ammoniate and modify attapulgite (ATP), ultimately, hydroxyapatite (HAP) is loaded onto the modified ATP to prepare a novel composite material (APTES/ATP@HAP),the study systematically explores the efficacy and mechanism of U(VI) extraction using APTES/ATP@HAP. The results indicate that under the conditions of pH= 4.0, T = 298.15 K, and t = 12 h, the maximum adsorption capacity of APTES/ATP@HAP for U(VI) reaches as high as 2128.72 mg·g^-1,this capacity is 2.61 times greater than that of HAP directly modified with amino group and 5.57 times that of ATP directly amino group functionalized, it is worth noting that APTES/ATP@HAP can remove 99.11% of U(VI) in actual wastewater when the dosage is 0.8 g ·L^-1, after five times of recycling, the removal rate of U ( VI) by APTES /ATP@HAP can still reach 99.06%. Promoting the release of phosphate in HAP through amino-triggered micro acidity is crucial for the formation of autunite,this work develops a new composite material for the efficient immobilization of U ( VI) in water and the mechanism of amino deprotonated local acidic microenvironment promoting the formation of autunite was elucidated.