协同型偕胺肟基聚乙烯无纺布吸附剂的制备及其对低浓度含铀废水的吸附研究

With the development of the nuclear industry, the problem of treating large amounts of radioactive waste has become a very urgent task. Recycling uranium from radioactive waste generated in the production of nuclear fuel, not only eliminate radioactive harm to the environment but also maintain the healthy development of nuclear power industry, moreover, that can achieve the re-use of recovered uranium. In this project, we will develop a new adsorbent utilizing radiation graft polymerization for uranium recycle from radioactive waste. PE nonwoven was used as a trunk material for the adsorbent, which was prepared by a series of modification reactions, as follows: (1) grafting of glycidyl methacrylate (GMA) onto PE nonwoven via radiation-induced graft polymerization (2) aminolyzation of PE nonwoven by the ring-opening reaction between of epoxy groups PGMA and N, N-dimethylethylenediamine (DMEDA); (3) Michael addition of amino groups with acrylonitrile (AN) to yield nitrile groups; (4) to reactive with halogenated alkanes to obtain antibacterial property; (5) amidoximation of the attached nitrile moieties by hydroxylamine. The behaviors of adsorption and desorption of uranyl ion of the PE nonwoven adsorbent will be carefully investigated in order to elucidate the mechanism of adsorption and desorption process. The performance of adsorption against uranyl ion and the service life of the adsorbent will be evaluated in radioactive waste generated in the production of nuclear fuel in laboratory at ambient temperature, in an attempt to achieve the adsorption capacity of 30 mg/g and service life of 5 cycles at the uranium concentration of 50 ppb (a period of 30-60 minutes). The activity of the wastewater after the adsorption of uranyl ion is less than 1Bq/L (uranium concentration less than 5 ppb), and meets emission standards.

本项目拟利用辐射接枝技术研发一种新型、高效且可多次循环使用的铀酰离子吸附剂。选择强度较高且耐水浸泡的聚乙烯（PE）无纺布为基材，使用低能电子束辐射引发甲基丙烯酸缩水甘油酯（GMA）单体与PE无纺布发生接枝聚合反应，再通过化学修饰的方式将丙烯腈单体引入PE无纺布，最后经过卤代烷烃和盐酸羟胺的化学处理，制备一种具有抗菌性的新型偕胺肟基吸附材料。研究该吸附剂对低浓度铀酰离子的吸附-脱附行为，阐明吸附-脱附机理；利用核燃料元件生产厂的放射性废水在实验室及现场评估偕肟胺基吸附材料对铀酰离子的吸附性能和循环使用次数。通过优化实验条件，筛选出在50 ppb铀酰离子浓度下（30-60分钟）吸附容量超过30 mg/g且能重复使用5次以上的偕胺肟基PE无纺布吸附材料。吸附后的废水中剩余铀酰离子的活度小于1Bq/L，溶液中铀酰离子浓度小于5 ppb，达到排放指标。

在项目执行期间，利用辐射接枝和化学修饰制备了三种吸附铀用PE-HOPO、PE-g-P(AO-co-MAA)和PE-AO无纺布材料，并研究了接枝反应参数对GMA接枝率的影响。基于辐射接枝法分别制备了含多氨基官能团的UHMWPE-AM纤维和UHMWPE-AO纤维。采用SEM、ATR-FTIR、XPS、TGA等对吸附材料进行表征测试，掌握吸附材料的理化性能与结构信息。开展了实验室模拟含铀废水吸附试验，利用ICP-AES测试手段评估材料的铀吸附性能。基于XPS和EXAFS表征手段对活性官能团与铀酰离子的配位结构进行表征，阐明材料吸附铀的机理机制。PE-HOPO无纺布具有优异的吸附选择性、去除率和耐盐性。PE-g-P(AO-co-MAA)无纺布的铀吸附量达到126.7mg/g，可将初始浓度为0.1 mg/L溶液降至3.2 μg/L（固液比：0.2g/L），增加固液比（10.0 g/L）可将铀浓度从40mg/L降低至30μg/L以下。UHMWPE-AM纤维在低浓度铀溶液中表现出优异的吸附效果，可将铀浓度从200μg/L降低至0.48μg/L（固液比：2.0g/L）。UHMWPE-AO纤维的铀吸附性能进一步得到提升，可将初始浓度为40 mg/L溶液降至16 μg/L（固液比：2.0g/L），去除率达到99.96%。XPS表征结果证实AO基吸附材料是通过偕胺肟基中“NH2”与“OH”与铀酰离子进行配位从而实现对铀酰离子的富集。EXAFS表征结果表明UHMWPE-AM纤维通过胺基取代碳酸铀酰中的碳酸根实现对铀酰离子的富集。本项目研制了一系列富集铀用功能无纺布和纤维吸附材料，并对材料的制备工艺、理化性能、铀吸附性能和吸附机理进行系统研究和讨论，为制备高铀吸附性能材料提供了理论依据。