放射性核素铯具有强放射性，半衰期长，危害大，严重威胁着人体健康和水体安全。研究开发去除放射性铯的关键技术，能够为放射性污染控制、水源放射性污染事故应对和减轻公众和环境健康危害提供有力的技术支持，对于保障饮用水的放射性安全具有重要意义。

本文通过共混改性和表面改性制备了两种不同的GO/PB/PVDF改性膜，利用氧化石墨烯的高比表面积和丰富的含氧官能团为PB提供了附着位点，提高了PB的分散性能，从而提高对铯的截留能力，且改性膜具有较高的水通量。

本研究表明，共混改性膜的最佳PB质量分数为5.0 wt%，GO 添加量为0.1%。此时，改性膜具有1638.2 LMH/bar高水通量以及99.6%的较高铯去除率。吸附动力学和等温线的模型拟合结果表明，吸附过程遵循准二级动力学和Langmuir等温线模型，且最大吸附容量为20.07 mg/g。热力学结果表明吸附过程是自发放热的。过滤实验表明，在共存离子Na⁺, Ca²⁺和Mg²⁺存在情况下，Cs⁺去除率高于97%。由于K⁺与Cs⁺水合离子半径接近，能够与铯竞争吸附位点，Cs⁺去除效率降低至70%。pH为3-10范围内，铯去除率均超过93.7%。天然有机质（Suwannee River natural organic matter, SRNOM）配水，地表水和自来水中共存有机与无机组分存在下，铯去除率保持在99.1%以上，说明改性膜有望用于实际含铯地表水处理。再生结果表明共混改性膜具有良好的稀硝酸和氯化铵再生能力，再生3次之后，仍具备高于80%的除铯率。

表面改性膜的最佳PB负载量为3次负载，其长效去除效果优于共混改性膜，24 h铯去除率可达95.4%以上。静态吸附实验表明，溶液中铯离子浓度低于5 mg/L时，2 h即可吸附平衡，这是由于表面改性膜上普鲁士蓝暴露在膜表面，更有利于与溶液中铯离子的接触。该膜吸附过程符合准二级动力学和Langmuir等温线模型，最大吸附容量为448.12 mg/g，说明表面改性更有利于普鲁士蓝的单层负载。过滤实验表明，共存离子存在下，Cs⁺去除率高于84.4%且遵循Na⁺ > Mg²⁺> Ca²⁺ > K⁺。pH较低时，大量的H⁺会通过离子交换作用影响铯的去除，但去除率仍高于87%。SRNOM配水对膜过滤性能有积极影响，前6 h去除率将近100%。再生实验结果显示，表面改性膜具有良好的稀硝酸和氯化铵再生能力，再生3次之后，仍具备高于85%的铯去除率。稳定性评价结果显示，两种改性膜在超声和酸性条件下具备良好的稳定性，强碱性会造成普鲁士蓝分解，实际操作中需要严格避免。

综上，两种改性膜各具优点，表面改性膜吸附容量大，长效运行效果好，相比于共混改性膜受共存离子影响较小，更有利于发挥普鲁士蓝的选择性除铯性能；而共混改性膜制备方法简单，通量大，酸性条件下除铯性能优于表面改性膜，且其稳定性更好。实际水处理中，可根据进水水质条件及进水水量选择适合的膜类型。本研究为低压膜在在放射性水体方面的应用提供了一个新的思路，具有一定的科学价值。

The radioactive nuclide cesium with strong radioactivity and long half-life seriously threatens human health and water safety. Research on the key technologies for the removal of radioactive cesium can provide technical support for the control of radioactive pollution, the response to water source radioactive accidents and the reduce of possible health hazards, which is of great significance to ensure the radioactive safety of drinking water.

In this paper, two kinds of GO/PB/PVDF modified membranes were prepared by blending and surface modification. The graphene oxide with high specific surface area and abundant oxygen-containing functional groups provided the attachment sites for PB and improved its dispersibility. Therefore, the modified membrane had high cesium removal rate and water flux.

The study showed that the blending modified membrane had high high water flux of 1638.2 LMH/bar and cesium removal rate of 99.6% when the PB was 5.0 wt% and GO was 0.1%. The results of adsorption kinetics and isotherm model fitting indicated that the adsorption process followed pseudo-second order kinetics and Langmuir isotherm model, and the maximum adsorption capacity was 20.07 mg/g. The thermodynamic results illustrated that the adsorption process was spontaneous and exothermic. The filtration experiment showed that the removal rate of cesium was higher than 97% in the presence of Na⁺, Ca²⁺ and Mg²⁺. Because of the hydrated ion radii of K⁺ was close to Cs⁺, it competed for the adsorption sites with cesium and reduced the removal rate of Cs⁺ to 70%. The removal rate of cesium exceeded 93.7% in the pH range from 3 to 10. In the presence of organic and inorganic components in the synthetic water containing Suwannee River natural organic matter, surface water and tap water, the removal rate of cesium remained above 99.1%, which indicated that the modified membrane was expected to be used in the actual treatment of surface water containing cesium. Furthermore, an 80% Cs removal rate was still achieved after three times regeneration by NH₄Cl and HNO₃ solution in the first 2 hours, which demonstrated excellent regeneration capacity.

When the PB loading time was 3 times, the cesium removal rate of the surface modified membrane could reach more than 95.4% in 24 h. The static adsorption experiments showed that the adsorption equilibrium could be achieved in 2 h, which was due to the PB was exposed to the surface of the membrane and more conducive to contact with cesium in solution. The maximum adsorption capacity of the membrane was 448.12 mg/g, which indicated that the surface modification was more beneficial to the monolayer loading of PB. The results of filtration experiments illustrated that the removal rate of Cs⁺ was higher than 84.4% in the presence of coexisting ions and followed Na⁺ > Mg²⁺ > Ca²⁺ > K⁺. At low pH, a large amount of H⁺ would affect the removal of cesium by ion exchange, but the removal rate was still higher than 87%. SRNOM had a positive effect on the membrane filtration performance and the removal rate was nearly 100% in 6 h. Furthermore, the removal rate of cesium was higher than 85% after three times of regeneration by NH₄Cl and HNO₃ solution, which demonstrated excellent regeneration capacity. Besides, the two kinds of modified membrane had good stability under ultrasonic and acid conditions but the PB would decompose in the strong alkalinity water and should be strictly avoided in practical water treatment.

        To sum up, both of modified membranes have their own advantages. The surface modified membrane has large adsorption capacity and good long-term operation effect. Compared with the blending modified membrane, it is less affected by coexisting ions, which is more conducive to the selective removal of cesium of PB. The preparation method of the blending modified membrane is simple. It has high flux and the cesium removal performance under acidic conditions is better than the surface modified membrane. Besides, the stability of the blending modified membrane is better than the surface modified membrane. In the practical water treatment, the suitable membrane type can be chosen according to the influent water quality and quantity. This study provides a new idea for the application of low-pressure membrane in radioactive water.