选择性吸附海水铀的纳米生物吸附剂的制备及性能研究

In this research proposal, immobilization treatment is to be conducted on the screened fungal strains which have large adsorption capacity and high adsorption speed for uranium and are easy to be modified chemically, and the hydroxyl, carboxyl, phosphoryl, sulfolipid and amido groups on the surfaces of the cells of the immobilized fungal strains are to be modified chemically to increase their strength and stability. In the mean time, the surface substrate modification with amino and carboxyl is to be conducted on the nano feldspar/K2MnSn2S6 particles using the organic polymer reagent, the modified particles are to be embedded, and the functional nano feldspar/K2MnSn2S6 particles, which have good stability, high resistance to oxidation, good dispersion and good selective adsorption for uranium in seawater, are to be obtained. The functional nano feldspar/K2MnSn2S6 particles are to be grafted with the chemically modified fungal strains to obtain the biosorbent and the structure of the biosorbent is to be characterized with Transmission electron microscope, X ray diffraction, Infrared spectrum and Nuclear magnetic resonance. Finally, the behavior, mechanism and kinetic model for the adsorption of the uranium from the seawater for the biosorbent are investigated and a novel method is to be proposed for adsorption of the uranium from the seawater. The research is a state of the art one in the field of extraction of uranium from the seawater and has great implication for the development of uranium resources in the sea.

本申请项目拟将课题组已筛选出的对铀的吸附容量大、吸附速度快、易于进行化学修饰的真菌菌株进行固定化；再对真菌细胞表面的羟基、羧基、磷酰基、硫酸脂基和酰胺基进行化学修饰，以增强其机械强度和化学稳定性。与此同时，采用高分子有机试剂，对纳米长石/K2MnSn2S6粒子，进行氨基功能化、羧基功能化等表面基体改性；再进行包埋固定，获得稳定性好、抗氧化性能强、分散性好的对海水铀具有选择性吸附的功能化纳米长石/K2MnSn2S6粒子。然后将表面基体改性后的纳米长石/K2MnSn2S6与化学修饰后的真菌接枝负载，获得由功能化纳米长石/K2MnSn2S6粒子和化学修饰真菌合成的选择性吸附海水铀的纳米生物吸附剂，并采用透射电镜、X 射线衍射、红外光谱、核磁共振等手段对其结构进行表征。最后研究其吸附海水铀的行为、机制和动力学模型，提出选择性吸附海水铀的新方法。

本项目通过对真菌菌株进行固定化和化学修饰，对钠长石/K2MnSn2S6粒子表面基体改性和固定化，将改性真菌接枝到钠长石/K2MnSn2S6粒子，合成了选择性吸附海水铀的纳米生物吸附剂；还通过化学和物理改性，合成了磷酸改性铁树叶和磷酸三丁酯改性樟树叶生物吸附剂。采用FT-IR、SEM-EDS、压汞仪、XPS等，对吸附剂进行了表征。进行了低浓度铀（模拟铀废水、模拟海水、海水）的吸附试验，考察了溶液pH、吸附剂用量、吸附时间、共存离子、铀离子初始浓度、温度等参数对吸附效果的影响。建立了吸附剂选择性吸附低浓度铀的吸附动力学，热力学和吸附等温线模型。阐述了吸附剂选择性吸附低浓度铀的吸附行为和吸附机理。揭示了吸附剂在不同洗脱剂、浓度、温度等条件下的脱附行为。结论如下：. （1）成功制备了对铀具有较好的吸附效果的黑曲霉粉末（RAN）、乙二胺改性黑曲霉(EMAN)、偕胺肟改性黑曲霉(AMAN)吸附剂。通过乙二胺、偕胺肟改性能提高黑曲霉对铀的选择性吸附性能。Langmuir模型、准二级动力学模型适合描述上述三种生物吸附剂对铀的吸附等温线和吸附动力学。EMAN表面的氨基与AMAN表面的偕胺肟基团参与了铀的成键作用；. （2）钠长石（RSF）对铀有较强的吸附能力。热活化和酸活化处理可以增强钠长石对铀的吸附能力。最佳热活化温度为450℃，最佳的硫酸浓度为98%的浓硫酸。Langmuir模型适合描述RSF、TASF和AASF对铀的吸附等温线，饱和吸附量分别为0.18、0.22和0.20 mg/g。RSF、TASF和AASF吸附剂中的羟基参与了铀的成键作用；. （3）TMP-g-AO吸附剂通过表面的偕胺肟基团与铀发生络合反应，能高效选择性识别铀。 准二级动力学模型适合描述TMP-g-AO对铀的吸附动力学。Langmuir模型适合描述TMP-g-AO对铀的吸附等温线，最大吸附量为35.37 mg/g。TMP-g-AO对自然海水进行3d的吸附，吸附率高达81.92%；. （4）通过化学、物理改性合成的磷酸改性铁树叶和磷酸三丁酯改性樟树叶生物吸附剂，对铀具有良好的吸附性能。在铀浓度为3.2到10 ug/L的模拟海水中，它们对铀的吸附率均高于80%。