發(fā)布時間：2018-02-16 22:06

  本文關鍵詞： 土壤污染物 離子吸附 碳材料 密度泛函理論計算　出處：《西南大學》2017年碩士論文　論文類型：學位論文

【摘要】：土壤是人類賴以生存的物質基礎和財富源泉。但我國在工農業(yè)生產迅猛發(fā)展和城鎮(zhèn)化進程日益加快的同時,土壤也受到了嚴重污染,這極大地威脅到生態(tài)安全和人類健康。無機污染物在土壤各種污染物中所占比重最大,其主要包括重金屬離子和陰離子污染物。人們在一直探索土壤無機污染物的去除方法,經(jīng)研究證實碳材料是一種很有潛力的無機污染物去除材料。現(xiàn)今,碳材料吸附離子的研究工作已被廣泛開展,但大多數(shù)工作是從宏觀角度出發(fā),研究離子吸附過程中的吸附量、吸附強度以及吸附過程等。本論文運用了密度泛函理論計算方法,從分子尺度上研究并闡明碳材料的離子吸附相關機制。論文以多環(huán)芳烴團簇結構作為碳材料的研究模型,選擇結構相對簡單的鹵素離子(X-=F~-,Cl~-,Br~-和I~-)作為陰離子代表;選擇堿金屬離子(M~+=Li~+、Na~+和K~+)、堿土金屬(M~(2+)=Be~(2+)、Mg~(2+)和Ca~(2+))及三價鑭離子(La~(3+))為金屬離子代表;以六個離子對(MX=LiF,NaF,KF,Li I,NaF,KF)作為陰陽離子對代表,運用密度泛函理論(DFT)深入而系統(tǒng)地研究了碳材料與它們之間的相互作用,并得出以下主要結論:(1)鹵素離子與金屬離子在碳材料表面的吸附行為具有一定的相似之處,但在本質上明顯不同。二者在碳材料表面的吸附強度均隨著離子半徑的增大而減弱,表現(xiàn)為為F~-Cl~-Br~-I~-和Li~+Na~+K~+(或Be~(2+)Mg~(2+)Ca~(2+));通過比較結合能的大小可知,鹵素離子中僅有F~-與碳材料的相互作用較強(Eb=-97.0 kJ·mol~(-1)),其它的吸附作用都很弱,因此可以輕松地從碳材料表面脫附,而金屬離子則都可以穩(wěn)定地吸附在碳材料表面。碳材料與陰離子、金屬離子的作用機制本質區(qū)別在于:與鹵素離子作用時為電子受體,電荷從鹵素離子轉移到碳材料表面,而在與金屬離子作用時為電子供體,電子由碳材料表面轉移到金屬離子上;(2)本論文進一步地分析了碳材料電子性質的改變對離子吸附行為的影響,選擇了常見的電子受體F原子對碳材料進行邊界官能化修飾。結果表明,當碳材料與離子相互作用時,鹵素離子在碳材料表面的吸附強度隨邊界官能化比例(Θ)的增大而逐漸增強,而金屬離子的吸附強度卻逐漸減弱。當Θ=100%時,F~-與碳材料表面的結合能已經(jīng)增大到接近原來的兩倍(-186.3 kJ·mol~(-1)),而金屬離子Li~+、Na~+和K~+離子的結合能卻分別降低到-95.7、-44.8和-25.9 kJ·mol~(-1),已經(jīng)明顯低于F~-的結合能大小。由此可知,官能團修飾及改變官能化比例可以調節(jié)碳材料的電子性質,進而調控鹵素離子和金屬離子的優(yōu)先吸附順序。(3)碳材料對水合離子吸附的研究表明,水合作用減弱了離子與碳材料間的直接作用強度。碳材料在與水合鹵素離子作用時,H_2O不僅可以與鹵素離子形成氫鍵,而且還通過O原子與碳材料發(fā)生相互作用。但當碳材料與水合金屬離子作用時,金屬離子與H_2O分子中的O原子形成化學鍵,然后H_2O再通過H原子與碳材料發(fā)生作用。也正因如此,水合作用對鹵素離子在未官能化碳材料表面的吸附強度影響較大,而對金屬離子則在完全官能化碳材料表面的吸附強度影響較大。(4)所有陰陽離子對都可以通過兩側以及同側垂直方式穩(wěn)定地吸附在碳材料表面,但垂直構型穩(wěn)定性要明顯的強于兩側構型,且金屬離子直接與碳材料直接的垂直構型結構更為穩(wěn)定。進一步研究表明,兩種垂直構型的相對穩(wěn)定性差異由與之對應的金屬離子和陰離子在碳材料表面的吸附強度之差所決定。當金屬離子的吸附作用明顯較強時,金屬離子直接與碳材料直接作用的構型為優(yōu)勢構型,而陰離子的吸附作用更強時,優(yōu)勢構型則轉變?yōu)殛庪x子離子直接與碳材料直接作用的構型;當二者的結合能相當時,兩種垂直構型的穩(wěn)定性比較接近。(5)碳材料的原子摻雜改變了離子的吸附模式,其中水平構型最為穩(wěn)定,而垂直構型的穩(wěn)定性較差甚至在某些情況下不能存在。結合能的計算結果表明,所有原子摻雜都增強了NaF在碳材料表面的吸附,且吸附強度按NOBBe順序依次增強。但是,含摻雜原子的碳材料對離子對吸附的調節(jié)機制并不相同,缺電子原子Be和B摻雜對NaF吸附的促進源于摻雜原子與F~-的直接作用,而富電子原子N和O摻雜則主要是通過改變碳材料體系π電子共軛促進NaF吸附,這也是它們對NaF的吸附強度弱于缺電子Be和B摻雜的原因。綜上所述,本論文深入而系統(tǒng)地研究了金屬離子、陰離子以及陰陽離子對在碳材料表面的吸附行為及吸附機制,比較它們吸附特性的異同,并揭示碳材料電子性質、水合作用、補償離子等因素對離子吸附行為及吸附效果的影響。研究結果對認識離子在碳材料上的吸附理論支撐和科學依據(jù),也為今后有針對性的選擇和制備碳材料提供了一些參考方向。
[Abstract]:The soil is the material basis of human survival and the source of wealth. But our country is accelerating in the industrial and agricultural production and the rapid development of the urbanization process at the same time, the soil has been seriously polluted, which greatly threaten the ecological safety and human health. The inorganic pollutants in the soil of various pollutants in the largest proportion, the main including heavy metal ions and anionic pollutants. People have been exploring methods for removal of inorganic contaminants in soil, the study confirmed that the carbon material is a kind of promising material removal of inorganic pollutants. Nowadays, ion adsorption of carbon materials in the research work has been carried out widely, but most of the work is from a macro perspective, the adsorption capacity of ion adsorption in the process of adsorption strength and adsorption process. This paper uses density functional theory calculation method, research and clarify the ion adsorption of carbon materials from molecular scale Based on the related mechanism. PAHs cluster structure as the research model of carbon materials, halogen ion selective relatively simple structure (X-=F~-, Cl~-, Br~- and I~-) as the representative of anion; alkali metal ions (M~+=Li~+, Na~+ and K~+), alkaline earth metal (M~ (2+) =Be~ (2+), Mg~ (2+) and Ca~ (2+)) and trivalent lanthanide ions (La~ (3+)) is a metal ion with six representatives; ion pair (MX=LiF, NaF, KF, Li, I, NaF, KF) as the representative of ions, using density functional theory (DFT) thorough and systematic research of carbon materials and the interaction between them, and the main conclusions are as follows: (1) halogen ions and metal ions have some similarities in the adsorption behavior of carbon materials on the surface, but in essence are obviously different. The two adsorption on the surface of the carbon material strength are increased with the increase of ionic radius and the decrease of the performance for F~-Cl~-Br~-I~- and Li~+Na~+K~+ (or Be~ (2+) Mg~ (2+) Ca~ (2+)); by comparing the binding energy of F~-, only with a carbon material in the strong interaction of halogen ions (Eb=-97.0 kJ - mol~ (-1)), the other adsorption effect is very weak, so we can easily from the surface of the carbon material desorption of metal ions can be stably adsorbed on the surface of the carbon material. The carbon material with anion, mechanism of metal ions is the essential difference between function and halogen ions for electron acceptor charge transfer from halogen ions to the surface of the carbon material, and with metal ions as electron donor, electron transfer from the surface of the carbon material to the metal ions (; 2) this paper analyses the influence of electronic properties of carbon materials on the adsorption behavior of the ion, choose the common electron acceptor F atom boundary functionalized modification of carbon materials. The results show that when the carbon materials and ionic interaction, from halogen With the boundary of functionalized proportion in the adsorption strength of carbon materials (PE) surface increases gradually increased, while the adsorption strength of metal ion is weakened gradually. When introducing =100%, the combination of F~- and carbon material surface energy has increased to nearly two times the original (-186.3 kJ - mol~ (-1)), and the metal ions of Li~+, combined with Na~+ and K~+ ions was decreased to -95.7, -44.8 and -25.9 kJ mol~ (-1), has been significantly lower than the F~- combined size. Therefore, the electronic properties of modified and functionalized carbon material ratio can be adjusted, and then adjust the priority sequence control and metal halide ion adsorption ion. (3) research of carbon materials on the hydration of ion adsorption showed that hydration weakens the direct effect of ionic strength and carbon materials. Carbon material with hydrated ions, H_2O can not only form hydrogen bond and halogen ions, but also by O Interact with carbon materials. But when carbon materials and hydrated metal ions, metal ions and H_2O molecules in O atoms form chemical bonds, then H_2O effect of H atoms and carbon materials through. Because of this, the hydration effect on the adsorption strength of halogen ions of carbon material on the surface non functional, and metal ions in fully functionalized carbon adsorption strength of material surface has great influence. (4) of all ions on can be stably adsorbed on the surface of the carbon material by both sides and the same side vertical mode, but the vertical configuration stability are stronger than both sides of configuration, vertical configuration and structure of metal ions direct and direct carbon material is more stable. Further study showed that the relative stability of the difference between the two vertical configuration by the corresponding metal ions and anions on the adsorption strength of carbon materials on the surface of the difference Decided. When the adsorption of metal ions was strong, metal ions and carbon materials directly for the advantage of the configuration configuration, and stronger adsorption of anions, the advantage configuration was transformed into anion ion directly with the direct effect of carbon materials with configuration; when the two can be quite close to two, stability vertical configuration. (5) carbon atom doped ion adsorption mode change, the level of configuration of the most stable, and poor stability of vertical structure exists even in some cases not. Combined with the calculation results can show that all atoms have enhanced the adsorption of NaF on the surface of the carbon material, and the adsorption according to the NOBBe sequence of strength enhancement. However, carbon material containing doping on the regulation mechanism of ions on the adsorption is not the same, electron deficient atom Be and B doping on the adsorption of NaF on promoting source doping With the direct effect of F~-, and the electron rich atom N and O doping is mainly through the change of carbon material system pi electron conjugated promoted NaF adsorption, which is their adsorption strength on NaF weak in electron deficient Be and B doping. In summary, this thesis in-depth and systematic study of metal ions, anions, Yin and Yang the ions on the adsorption behavior and mechanism of carbon material surface, compare their adsorption properties, and reveal the electronic properties of carbon materials, hydration, compensation effect of ions on ion adsorption behavior and adsorption effect. The results of studying on the adsorption of ions in carbon materials, theoretical support and scientific basis for the future the selection and preparation of carbon materials provide some reference.

【學位授予單位】：西南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O647.3;X53

【參考文獻】

相關期刊論文 前10條

1 王博;葉春;李法云;曲乾;陳鑫;;水生植物制生物炭對硝態(tài)氮的吸附規(guī)律研究[J];中國環(huán)境科學;2017年01期

2 串麗敏;鄭懷國;趙同科;趙靜娟;顏志輝;張曉靜;;基于專利文獻分析的土壤污染修復技術發(fā)展現(xiàn)狀與展望[J];農業(yè)環(huán)境科學學報;2016年11期

3 趙慧慧;肖嫻;裴孟;趙遠;梁玉婷;;長期石油污染對鹽堿化土壤中微生物群落分子生態(tài)網(wǎng)絡的影響[J];環(huán)境科學;2016年09期

4 江文琛;;重金屬污染場地化學氧化還原修復技術適用性探討[J];資源節(jié)約與環(huán)保;2016年04期

5 謝正蘭;孫玉川;張媚;余琴;徐昕;;巖溶地下河流域表層土壤有機氯農藥分布特征及來源分析[J];環(huán)境科學;2016年03期

6 葉群峰;周小玲;;金華市螢石礦區(qū)土壤氟污染評價[J];環(huán)境科學;2015年07期

7 馬鋒鋒;趙保衛(wèi);鐘金魁;刁靜茹;張藝;;牛糞生物炭對磷的吸附特性及其影響因素研究[J];中國環(huán)境科學;2015年04期

8 串麗敏;趙同科;鄭懷國;趙靜娟;張曉靜;譚翠萍;李光達;;土壤重金屬污染修復技術研究進展[J];環(huán)境科學與技術;2014年S2期

9 李林;周啟星;;我國典型城市大氣汞污染及對人體健康的影響[J];生態(tài)毒理學報;2014年05期

10 潘永剛;石云峰;;土壤污染熱修復裝置的研究[J];環(huán)境工程;2014年07期

相關博士學位論文 前1條

1 何巨龍;B-C-N新材料的實驗合成與相關材料的第一性原理研究[D];燕山大學;2003年

相關碩士學位論文 前2條

1 蔣婷婷;不同改性蒙脫土的制備及其對土壤重金屬的穩(wěn)定化作用研究[D];華東理工大學;2016年

2 樸春香;延邊地區(qū)硝酸鹽、亞硝酸鹽污染現(xiàn)狀分析[D];延邊大學;2006年

，

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