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偕氨肟基纤维吸附材料的制备及海水提铀研究
论文作者:童鞋论文网  论文来源:www.txlunwenw.com  发布时间:2019/10/24 9:10:05  

摘要:随着全球经济的快速发展和全球化石能源的日益枯竭,核能的大规模利用和发展成为必然选择。铀(U)作为现代核工业赖以发展的基础资源,是一种重要的稀有战略资源。随着全球陆地铀矿资源的日益匮乏,开发海水提铀技术以获取大量铀资源势在必行。设计与合成具有化学稳定性好、机械强度好、高选择性、高吸附容量、长的使用寿命和制备成本低的海水提铀用纤维型吸附材料以及建立新型海水提铀用吸附材料制备工艺是目前研究的重点。本论文选用已商业化、相对廉价的聚乙烯/聚丙烯(PE/PP)皮芯纤维作为基材,采用辐射接枝聚合(RIGP)技术,将单体丙烯腈(AN)和丙烯酸(AA)接枝到基材纤维上,随后进行氨肟化反应,将对铀酰离子具有很强螯合能力及高选择性的偕氨肟基团引入到基材骨架上,制备出吸附性能优异的偕氨肟基PE/PP(ABP)纤维吸附材料。详细研究了吸收剂量、单体浓度、反应温度和反应时间等工艺条件与接枝率的关系;并通过傅立叶变换红外光谱(FT-IR)、X-射线光电子能谱仪(XPS)、表面孔径吸附仪(BET)、正电子湮灭寿命谱(PALS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、热重分析仪(TGA)和电子单纤维强力仪对改性前后PE/PP纤维的化学组成、微观形貌结构、热稳定性能和机械性能进行了分析。研究结果表明利用RIGP技术制备的ABP纤维具有良好的热稳定性能和机械性能。通过模拟海水批次静态吸附和天然海水流动吸附研究了材料对U的吸附性能。基于RIGP技术制备的ABP纤维在模拟海水中对U的吸附容量达到2.27 mg/g,并且其对U的吸附容量大于V。吸附动力学实验表明ABP纤维吸附501 h后,其对U的吸附达到平衡,且平衡吸附容量为2.94 mg/g;ABP纤维吸附材料在5次循环使用后仍能保持较高的吸附容量,并且可以继续循环再生使用。吸附等温线实验表明Langmuir和Freundlich模型都能较好的描述ABP纤维的吸附过程,且更符合Freundlich模型。ABP纤维在天然海水中吸附90天后达到饱和,其对U最大的吸附容量达到3.61 mg/g。基于RIGP结合硝酸铈铵(CAN)引发接枝聚合(CIGP)技术合成制备出具有3D分级多孔结构的高比表面积偕氨肟基PE/PP(H-ABP)纤维吸附材料。H-ABP纤维相对传统ABP纤维具有更优的吸附性能,开创了一种铀酰离子吸附材料制备的新方法。首先,利用RIGP技术对基材PE/PP纤维进行预辐射接枝丙烯酸羟乙酯(HEA)得到PE/PP-g-PHEA纤维。详细地研究了吸收剂量与PE/PP-g-PHEA纤维接枝率之间的关系;然后利用CIGP技术,通过CAN在酸性条件下对PE/PP-g-PHEA纤维引发共接枝AN和AA得到PE/PP-g-PHEA-(PAA-co-PAN)纤维,并研究了PE/PP-g-PHEA纤维的接枝率、反应时间、反应温度等工艺条件与PE/PP-g-PHEA-(PAA-co-PAN)纤维接枝率之间的关系;最后通过氨肟化反应制备出H-ABP纤维。通过FT-IR、XPS、BET、PALS、SEM、ESEM、TEM和电子单纤维强力仪对改性前后纤维的化学结构、微观形貌和机械性能进行研究,研究结果表明利用新型的RIGP-CIGP技术可以成功的在高分子纤维吸附材料上构建3D分级多孔结构,且纤维吸附材料的形貌结构以及比表面积高度可控;H-ABP纤维在模拟海水中对U的吸附容量达到了5.73 mg/g,并且其对U具有非常好的选择性。H-ABP纤维在模拟海水中进行了10次吸附-脱附循环再生实验以及在天然海水中吸附90天后,其对U的吸附容量达到11.50 mg/g,结果表明H-ABP纤维吸附材料对U的吸附容量和循环使用寿命都高于现有文献报道。H-ABP纤维吸附材料在天然海水中对U的吸附容量高于V,颠覆了传统ABP纤维吸附材料的U、V选择性。这种新型的海水提铀用吸附材料的合成及制备方法(RIGP-CIGP)对于海水提铀的工业化进程具有重要的里程碑意义。

With the rapid development of globaleconomy and the increasingly depletion of global fossil energy, the large-scaleutilization and development of nuclear energy have become an inevitable choice.Uranium (U), as the basic resource for the development of modern nuclearindustry, is an important rare strategic resource. With the increasing scarcityof global land uranium resources, it is imperative to develop technology foruranium extraction from seawater to obtain large amounts of uranium resources.Designing and synthesizing fibrous adsorbent with good chemical stability, goodmechanical strength, high selectivity, high adsorption capacity, a long servicelife and low cost for uranium extraction from seawater, as well as establishinga new process for preparing fibrous adsorbent for uranium extraction fromseawater are the focus of current research.

In this article, the commercialized and lowcost polyethylene-coated polypropylene skin-core (PE/PP) fibers were used as substratematerials. Radiation-induced graft polymerization (RIGP) technology withacrylonitrile (AN) and acrylic acid (AA) and following amidoximation were usedto preparation of amidoxime-based PE/PP fibrous adsorbent (ABP) with strongchelating ability for uranyl ions, high selectivity and excellent adsorptionproperties. The effects of absorbed dose, reaction time, reaction temperatureand monomer concentration on the degree of grafting were investigated indetail. The chemical structure, micromorphology, thermal properties, andmechanical properties of the pristine and modified PE/PP fibers were carefullycharacterized by fourier transform infrared spectroscopy (FT-IR), X-rayphotoelectron spectroscopy (XPS), brunauer-Emmet-Teller (BET), positron annihilationlifetime spectroscopy (PALS), scanning electron microscopy (SEM), transmissionelectron microscope (TEM), thermogravimetric analysis (TGA), and an electronicsingle fiber tensile strength tester. The results show that ABP fibers havebeen successfully prepared and have good thermal stability and mechanicalproperties. The uranium adsorption capacity was 2.27 mg/g in simulated seawaterfor ABP fibers, and the uranium adsorption capacity was larger than that ofvanadium (V). The adsorption kinetics experiment showed that the ABP fibersreached adsorption balance after 50 h with a uranium adsorption capacity of2.94 mg/g, and ABP fibrous adsorbent still maintain a high adsorption capacityafter five adsorption-desorption cycles, and is easy to recycle. The adsorptionprocess of ABP fibrous adsorbent follow both Langmuir and Freundlich models andare more in line with the Freundlich model. The ABP fibrous adsorbent reachedsaturation after 90 days of adsorption, and the maximum adsorption capacity was3.61 mg/g.

A novel technology for RIGP combined withcerium ammonium nitrate (CAN) initiated graft copolymerization (CIGP) was usedto synthesize a 3D hierarchical porous structure, high specific surface areaamidoxime-based PE/PP fibrous adsorbent (H-ABP) fiber. Firstly, PE/PP-g-PHEAfibers were obtained by pre-irradiation grafting HEA onto PE/PP fibers usingRIGP technology. The effects of absorbed dose on the degree of grafting ofPE/PP-g-PHEA fibers were investigated in detail. Secondly, PE/PP-g-PHEA-(PAA-co-PAN)fibers were obtained by CAN initiated copolymerization of AN and AA onto thePE/PP-g-PHEA fibers. The effect of the degree of grafting of PE/PP-g-PHEAfibers, reaction time, reaction temperature on the degree of grafting ofPE/PP-g-PHEA-(PAA-co-PAN) fibers were studied. Finally, H-ABP fibrous adsorbentwas prepared by ammoniation. The chemical structure, micromorphology, thermalproperties, and mechanical properties of the pristine and modified PE/PP fiberswere carefully characterized by FT-IR, XPS, BET, PALS, SEM, environmentalscanning electron microscopy (ESEM), TEM and an electronic single fiber tensilestrength tester.

关键词:海水提铀;PE/PP纤维;辐射接枝聚合;硝酸铈铵;吸附

uranium extraction from seawater;PE/PP fibers;RIGP;CAN;adsorption

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