Po放射性廢水凈化及檢測模擬實(shí)驗(yàn)研究
發(fā)布時間：2018-08-17 10:38
【摘要】：Po是乏燃料處理、鈾礦開采及鉛鉍冷卻反應(yīng)堆核事故產(chǎn)生的放射性廢水中的重要核素之一,其同時具有極毒性和放射性,凈化與檢測這種放射性核素是核能可持續(xù)發(fā)展必須考慮的問題之一。本文采用化學(xué)性質(zhì)相似的非放射性碲代替放射性及高毒性釙,選擇載銀不銹鋼編織網(wǎng)和氧化石墨烯兩種吸附載體,開展了水中Te(Ⅳ)的吸附行為及機(jī)理研究;在此基礎(chǔ)上,以氧化石墨烯為前驅(qū)體,以抗壞血酸、亞硫酸氫鈉及乙二胺為還原劑,構(gòu)建納米銀/石墨烯水凝膠,并確定碲信號最強(qiáng)的乙二胺還原誘導(dǎo)自組合納米銀/石墨烯水凝膠為基底材料,開展了表面增強(qiáng)拉曼散射技術(shù)對水中微量碲元素檢測的探索研究,主要研究結(jié)果如下:通過開展鍍銅電流、吸附時間及共存碘離子濃度對載銀不銹鋼編織網(wǎng)吸附Te(Ⅳ)行為影響的研究,結(jié)果表明:鍍銅電流對載銀不銹鋼編織網(wǎng)吸附Te(Ⅳ)具有顯著的正向性影響,這是不銹鋼編織網(wǎng)表面銀負(fù)載量隨鍍銅電流增加而增大的結(jié)果;鍍銀時間0.5 h和鍍銀時間2.5 h的不銹鋼編織對Te(Ⅳ)的吸附隨吸附時間的變化具有明顯地前期快速上升階段和后期平緩階段,而鍍銀時間1.5 h的不銹鋼編織網(wǎng)對Te(Ⅳ)的吸附率隨吸附時間增加以恒定速率上升,在吸附64 h時,吸附率達(dá)到63±0.1%,載銀不銹鋼表面銀膜表面積隨鍍銀時間延長而變化是產(chǎn)生該現(xiàn)象的主要原因;載銀不銹鋼編織網(wǎng)對水中Te(Ⅳ)的吸附隨共存碘離子濃度向增加呈現(xiàn)先下降后上升趨勢,該現(xiàn)象是碘離子、Te(Ⅳ)種態(tài)競爭吸附和銀、Te(Ⅳ)接觸面積變化共同作用的結(jié)果。微觀結(jié)構(gòu)與物相分析表明:銀膜表面吸附形成的化合物呈現(xiàn)明顯的正四價氧化物形式和Ag2Te化合物形式,確定Te(Ⅳ)自發(fā)沉積和酸性條件下銀、Te(Ⅳ)反應(yīng)生成Ag2Te是載銀不銹鋼編織網(wǎng)吸附Te(Ⅳ)的主要機(jī)制。通過開展吸附時間、水溶液pH及氧化石墨烯濃度等因素影響氧化石墨烯吸附Te(Ⅳ)的研究,結(jié)果表明:氧化石墨烯表面吸附位點(diǎn)隨吸附時間增加而逐漸減少,這是導(dǎo)致Te(Ⅳ)吸附率隨吸附時間增加先上升后不變的主要原因;pH對氧化石墨烯表面官能團(tuán)與Te(Ⅳ)間親合力和水中Te(Ⅳ)溶解性及種態(tài)影響的綜合作用,導(dǎo)致Te(Ⅳ)吸附率隨pH增加呈現(xiàn)先上升后下降的趨勢,并在pH值4.7左右,吸附率達(dá)到最大;氧化石墨烯對Te(Ⅳ)的吸附率隨其濃度的增加先上升后不變,這是吸附位點(diǎn)和氧化石墨烯片團(tuán)聚程度隨氧化石墨烯濃度增加而增大的結(jié)果�；谏鲜鰧�(shí)驗(yàn),對氧化石墨烯吸附Te(Ⅳ)的動力學(xué)和等溫線進(jìn)行了研究,結(jié)果顯示:氧化石墨烯吸附Te(Ⅳ)動力學(xué)數(shù)據(jù)符合偽二階動力學(xué)方程,吸附平衡數(shù)據(jù)符合Sips方程及Freunlich方程,表明氧化石墨烯表面各吸附位點(diǎn)不均勻,對Te(Ⅳ)的吸附為非單層吸附,且隨著吸附的進(jìn)行,吸附限速步驟由內(nèi)擴(kuò)散逐漸轉(zhuǎn)變?yōu)槟U(kuò)散,據(jù)此可得氧化石墨烯吸附Te(Ⅳ)離子是一個包含多種作用的復(fù)雜過程。微觀結(jié)構(gòu)及價態(tài)分析表明氧化石墨烯吸附Te(Ⅳ)并不會導(dǎo)致其化學(xué)價的改變,吸附機(jī)制涉及環(huán)氧基、羧基等含氧官能團(tuán)和石墨烯苯環(huán)結(jié)構(gòu)對碲離子的相互作用。利用表面增強(qiáng)拉曼光譜,開展了水中微量Te(Ⅳ)檢測實(shí)驗(yàn)研究。通過對抗壞血酸、亞硫酸氫鈉和乙二胺還原誘導(dǎo)自組合納米銀/石墨烯水凝膠吸附Te(Ⅳ)后的拉曼信號進(jìn)行對比,發(fā)現(xiàn)乙二胺還原誘導(dǎo)自組合納米銀/石墨烯在584.9 cm-1的Te-O峰和642.9 cm-1的Te=O=Te振動峰顯著增強(qiáng),而抗壞血酸和亞硫酸氫鈉還原誘導(dǎo)自組合納米銀/石墨烯水凝膠基底對碲的拉曼信號并無明顯增強(qiáng),確定乙二胺還原自組合納米銀/石墨烯水凝膠為基底材料,進(jìn)一步開展水溶液pH值和Te(Ⅳ)濃度對基底材料吸附后拉曼信號影響的實(shí)驗(yàn)研究,結(jié)果表明:pH=5.5和584.9 cm-1峰分別為水中微量Te(Ⅳ)的檢測條件和標(biāo)志信號;在Te(Ⅳ)濃度7.84×10-9-7.84×10-5M范圍內(nèi),該信號峰強(qiáng)度隨Te(Ⅳ)濃度下降而降低,檢出限約 100nM�；谏鲜鲅芯拷Y(jié)果可得,Ag是潛在的凈化水中Po(Ⅳ)的強(qiáng)吸附載體,氧化石墨烯則是對微量Po(Ⅳ)吸附性能良好的優(yōu)選基底材料,本項(xiàng)工作有望為放射性廢水中的釙提供一種新的有效、快捷的凈化及檢測方法。
[Abstract]:Po is one of the most important nuclides in radioactive wastewater from spent fuel treatment, uranium mining and lead-bismuth cooled reactor accidents. It is extremely toxic and radioactive at the same time. Purification and detection of this kind of radionuclide is one of the problems that must be considered in the sustainable development of nuclear energy. The adsorption behavior and mechanism of Te(IV) in water were studied by choosing silver-loaded stainless steel braided mesh and graphene oxide as adsorbent carriers. On this basis, nano-silver/graphene hydrogel was constructed with graphene oxide as precursor, ascorbic acid, sodium bisulfite and ethylenediamine as reductant, and tellurium signal was determined. The strongest ethylenediamine reduction-induced self-assembled nano-silver/graphene hydrogel was used as the substrate material to study the surface-enhanced Raman scattering (SERS) technique for the determination of Trace Tellurium in water. The main results are as follows: Adsorption of Te (IV) onto silver-loaded stainless steel braided mesh by copper plating current, adsorption time and coexisting iodine concentration were studied. The results show that the copper plating current has a significant positive effect on the adsorption of Te (IV) on the silver-loaded stainless steel braided mesh, which is the result of the increase of silver load on the surface of the stainless steel braided mesh with the increase of copper plating current. The adsorption rate of Te(IV) on stainless steel braided mesh with silver plating time of 1.5 h increased at a constant rate with the increase of adsorption time. The adsorption rate reached 63.0.1% at 64 H. The change of surface area of silver film on silver-loaded stainless steel with the extension of silver plating time was the main reason for this phenomenon. The adsorption of Te (IV) on the silver-loaded stainless steel braided mesh firstly decreased and then increased with the increase of the concentration of coexisting iodine ions. This phenomenon was the result of the joint action of iodine ions, competitive adsorption of Te (IV) species and the change of contact area of silver and Te (IV). The main mechanism of adsorption of Te(IV) on silver-loaded stainless steel braided mesh was the formation of Ag(IV) by the spontaneous deposition of Te(IV) and the reaction of Ag(IV) with Ag(IV) under acidic conditions. The results show that the adsorption sites on the surface of graphene oxide decrease with the increase of adsorption time, which is the main reason that the adsorption rate of Te (IV) increases first and then remains unchanged with the increase of adsorption time. The adsorption rate of Te(IV) on graphene oxide increased first and then remained unchanged with the increase of pH, which was the result of the increase of adsorption sites and agglomeration degree of graphene oxide sheets with the increase of graphene oxide concentration. The kinetics and isotherms of adsorption of Te(IV) on graphene oxide were studied. The results showed that the kinetic data of adsorption of Te(IV) on graphene oxide conformed to pseudo-second-order kinetic equation. The adsorption equilibrium data conformed to Sips equation and Freunlich equation. The adsorption sites on graphene oxide surface were inhomogeneous and the adsorption of Te(IV) on graphene oxide was non-monolayer adsorption. Adsorption of Te (IV) ion by graphene oxide is a complex process involving many functions. Microstructure and valence analysis show that the adsorption of Te (IV) by graphene oxide does not change its chemical valence. The adsorption mechanism involves epoxy and carboxyl groups. The interaction between oxygen functional groups and graphene benzene ring structure on tellurium ion was studied by surface-enhanced Raman spectroscopy (SERS). The Raman signals of trace Te(IV) in water were compared with those of ascorbic acid, sodium bisulfite and ethylenediamine-induced self-assembled silver/graphene hydrogels. The Te-O peak and Te=O=Te vibration peak of 584.9 cm-1 and 642.9 cm-1 were significantly enhanced by reduction-induced self-assembly of nano-silver/graphene, while the Raman signal of Tellurium on the substrate of self-assembly nano-silver/graphene hydrogel induced by ascorbic acid and sodium bisulfite reduction was not significantly enhanced. It was confirmed that the self-assembly of nano-silver/graphene hydrogel by ethylenediamine reduction was formed. The influence of pH value and Te(IV) concentration on Raman signal after adsorption was studied. The results showed that the peak values of pH=5.5 and 584.9 cm-1 were the detection conditions and marker signals of trace Te(IV) in water, respectively. In the range of Te(IV) concentration 7.84 *10-9-7.84 *10-5 M, the peak intensity decreased with Te(IV) concentration. Based on the above results, Ag is a potential strong adsorption carrier for Po (IV) in purified water, and graphene oxide is a preferred substrate material with good adsorption performance for trace Po (IV). This work is expected to provide a new and effective method for the purification and detection of polonium in radioactive wastewater.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TL941
[Abstract]:Po is one of the most important nuclides in radioactive wastewater from spent fuel treatment, uranium mining and lead-bismuth cooled reactor accidents. It is extremely toxic and radioactive at the same time. Purification and detection of this kind of radionuclide is one of the problems that must be considered in the sustainable development of nuclear energy. The adsorption behavior and mechanism of Te(IV) in water were studied by choosing silver-loaded stainless steel braided mesh and graphene oxide as adsorbent carriers. On this basis, nano-silver/graphene hydrogel was constructed with graphene oxide as precursor, ascorbic acid, sodium bisulfite and ethylenediamine as reductant, and tellurium signal was determined. The strongest ethylenediamine reduction-induced self-assembled nano-silver/graphene hydrogel was used as the substrate material to study the surface-enhanced Raman scattering (SERS) technique for the determination of Trace Tellurium in water. The main results are as follows: Adsorption of Te (IV) onto silver-loaded stainless steel braided mesh by copper plating current, adsorption time and coexisting iodine concentration were studied. The results show that the copper plating current has a significant positive effect on the adsorption of Te (IV) on the silver-loaded stainless steel braided mesh, which is the result of the increase of silver load on the surface of the stainless steel braided mesh with the increase of copper plating current. The adsorption rate of Te(IV) on stainless steel braided mesh with silver plating time of 1.5 h increased at a constant rate with the increase of adsorption time. The adsorption rate reached 63.0.1% at 64 H. The change of surface area of silver film on silver-loaded stainless steel with the extension of silver plating time was the main reason for this phenomenon. The adsorption of Te (IV) on the silver-loaded stainless steel braided mesh firstly decreased and then increased with the increase of the concentration of coexisting iodine ions. This phenomenon was the result of the joint action of iodine ions, competitive adsorption of Te (IV) species and the change of contact area of silver and Te (IV). The main mechanism of adsorption of Te(IV) on silver-loaded stainless steel braided mesh was the formation of Ag(IV) by the spontaneous deposition of Te(IV) and the reaction of Ag(IV) with Ag(IV) under acidic conditions. The results show that the adsorption sites on the surface of graphene oxide decrease with the increase of adsorption time, which is the main reason that the adsorption rate of Te (IV) increases first and then remains unchanged with the increase of adsorption time. The adsorption rate of Te(IV) on graphene oxide increased first and then remained unchanged with the increase of pH, which was the result of the increase of adsorption sites and agglomeration degree of graphene oxide sheets with the increase of graphene oxide concentration. The kinetics and isotherms of adsorption of Te(IV) on graphene oxide were studied. The results showed that the kinetic data of adsorption of Te(IV) on graphene oxide conformed to pseudo-second-order kinetic equation. The adsorption equilibrium data conformed to Sips equation and Freunlich equation. The adsorption sites on graphene oxide surface were inhomogeneous and the adsorption of Te(IV) on graphene oxide was non-monolayer adsorption. Adsorption of Te (IV) ion by graphene oxide is a complex process involving many functions. Microstructure and valence analysis show that the adsorption of Te (IV) by graphene oxide does not change its chemical valence. The adsorption mechanism involves epoxy and carboxyl groups. The interaction between oxygen functional groups and graphene benzene ring structure on tellurium ion was studied by surface-enhanced Raman spectroscopy (SERS). The Raman signals of trace Te(IV) in water were compared with those of ascorbic acid, sodium bisulfite and ethylenediamine-induced self-assembled silver/graphene hydrogels. The Te-O peak and Te=O=Te vibration peak of 584.9 cm-1 and 642.9 cm-1 were significantly enhanced by reduction-induced self-assembly of nano-silver/graphene, while the Raman signal of Tellurium on the substrate of self-assembly nano-silver/graphene hydrogel induced by ascorbic acid and sodium bisulfite reduction was not significantly enhanced. It was confirmed that the self-assembly of nano-silver/graphene hydrogel by ethylenediamine reduction was formed. The influence of pH value and Te(IV) concentration on Raman signal after adsorption was studied. The results showed that the peak values of pH=5.5 and 584.9 cm-1 were the detection conditions and marker signals of trace Te(IV) in water, respectively. In the range of Te(IV) concentration 7.84 *10-9-7.84 *10-5 M, the peak intensity decreased with Te(IV) concentration. Based on the above results, Ag is a potential strong adsorption carrier for Po (IV) in purified water, and graphene oxide is a preferred substrate material with good adsorption performance for trace Po (IV). This work is expected to provide a new and effective method for the purification and detection of polonium in radioactive wastewater.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TL941
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