石墨烯負(fù)載零價(jià)納米鐵去除有機(jī)污染物的研究
發(fā)布時(shí)間：2019-05-09 07:36
【摘要】：自2004年石墨烯發(fā)現(xiàn)以來,就以其獨(dú)特結(jié)構(gòu)與性能引起人們的重視,并迅速成為諸多學(xué)科前沿研究的熱點(diǎn)。石墨烯具有獨(dú)特的二維平面結(jié)構(gòu)和極大的比表面積,使其成為負(fù)載無機(jī)納米粒子的理想載體,目前,已有一系列報(bào)道將石墨烯與功能性粒子結(jié)合起來制備出石墨烯復(fù)合材料。此外,零價(jià)納米鐵(nZVI)在環(huán)境修復(fù)中表現(xiàn)出非常明顯的優(yōu)勢,但在實(shí)際應(yīng)用中仍存在一些問題,如易氧化,易團(tuán)聚、制備成本高等,這些都限制了nZVI對環(huán)境污染物的去除效率。若將兩者結(jié)合起來,制備石墨烯負(fù)載零價(jià)納米鐵(nZVI/rGO)復(fù)合材料,不僅能抑制nZVI的團(tuán)聚提高其反應(yīng)活性,還拓展了石墨烯在環(huán)境修復(fù)領(lǐng)域的潛在應(yīng)用價(jià)值。本文主要以nZVI/rGO復(fù)合材料為研究對象,研究該材料去除有機(jī)污染物(羅丹明B、多溴二苯醚)的可行性,能夠?yàn)閚ZVI/rGO的實(shí)際應(yīng)用提供一定的參考價(jià)值。主要研究內(nèi)容如下:采用液相還原法制備nZVI;通過改進(jìn)的Hummers方法制備氧化石墨(GO),以硼氫化鈉為還原劑制備nZVI/rGO復(fù)合材料。之后對所制備的材料進(jìn)行分析表征,主要包括:掃描電鏡、X射線衍射、拉曼光譜、BET比表面積以及X射線光電子能譜。利用石墨烯負(fù)載零價(jià)納米鐵復(fù)合材料去除羅丹明B(Rh B),并采用RSM和ANN-GA建模的方法,優(yōu)化羅丹明B去除率的影響因素(pH、初始濃度、溫度以及反應(yīng)時(shí)間)。結(jié)果表明,兩個模型的預(yù)測值都能較好的與實(shí)驗(yàn)值吻合,相比而言,ANN-GA模型的預(yù)測結(jié)果更為準(zhǔn)確。RSM通過方差分析得出初始濃度是最重要的影響因素。另外,通過擬合nZVI/rGO去除羅丹明B的吸附等溫線和動力學(xué)方程發(fā)現(xiàn),Freundlich方程和偽二級動力學(xué)能更好地描述nZVI/rGO對羅丹明B的吸附過程。研究并比較nZVI和nZVI/rGO對BDE-47、BDE-100、BDE-154降解效果。在反應(yīng)初級階段兩種材料對PBDEs降解速度較快,隨著吸附作用及還原能力的減弱其降解速率也隨之下降。另外,由于BDE-154含有較多的溴原子,與BDE-47和BDE-100相比更容易降解,因此BDE-154不僅降解速度快,還具有較高降解率。通過對動力學(xué)模型的研究分析發(fā)現(xiàn),nZVI和nZVI/rGO對PBDEs的降解效果為偽一級反應(yīng)動力學(xué)或偽二級反應(yīng)動力學(xué)。另外,根據(jù)課題組實(shí)際情況,通過理論計(jì)算,對PBDEs的實(shí)驗(yàn)結(jié)果進(jìn)行補(bǔ)充。采用B3PW91/6-311+G(d,p)和PBE/TZ2P/ZORA方法對BDE-28、BDE-30、BDE-32、BDE-51、BDE-116與BDE-166進(jìn)行結(jié)構(gòu)優(yōu)化,并將C-Br與C-O鍵鍵長與其實(shí)驗(yàn)值進(jìn)行比較;利用QST2的方法研究了BDE-7和BDE-12構(gòu)型過渡態(tài)以及陰離子態(tài)之間的轉(zhuǎn)換關(guān)系;研究了溶劑化條件下BDE-47、BDE-17、BDE-15、BDE-8、BDE-7和BDE-4陰離子的脫鹵路徑;通過建立定量構(gòu)效關(guān)系模型對所選擇的14種BDE同系物的脫溴速率常數(shù)進(jìn)行預(yù)測。
[Abstract]:Since graphene was discovered in 2004, it has attracted people's attention because of its unique structure and properties, and has rapidly become the focus of frontier research in many disciplines. Graphene has a unique two-dimensional plane structure and large specific surface area, which makes it an ideal carrier for loading inorganic nanoparticles. At present, there have been a series of reports that graphene and functional particles are combined to prepare graphene composites. In addition, zero-valent nano-iron (nZVI) shows a very obvious advantage in environmental remediation, but there are still some problems in practical application, such as easy oxidation, easy agglomeration and high preparation cost. These limit the removal efficiency of environmental pollutants by nZVI. The preparation of graphene-supported zero-valent iron nanocomposites (nZVI/rGO) can not only inhibit the aggregation of nZVI and improve its reactivity, but also expand the potential application value of graphene in the field of environmental remediation. In this paper, the feasibility of removing organic pollutants (rhodamine B, polybrominated diphenyl ether) from nZVI/rGO composites was studied, which can provide some reference value for the practical application of nZVI/rGO. The main contents are as follows: nZVI; was prepared by liquid phase reduction method and graphite oxide (GO), was prepared by modified Hummers method. NZVI/rGO composite was prepared by using sodium borohydride as reducing agent. The prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), BET specific surface area (BET) and X-ray photoelectron spectroscopy (XPS). The removal of Rhodamine B (Rh B), by graphene-loaded zero-valent iron nanocomposites was studied by using RSM and ANN-GA modeling methods to optimize the influencing factors of Rhodamine B removal rate (initial pH, concentration, temperature and reaction time). The results show that the predicted values of the two models are in good agreement with the experimental values. Compared with the experimental values, the prediction results of the ANN-GA model are more accurate, and the initial concentration of RSM is the most important influencing factor by ANOVA. In addition, by fitting the adsorption isotherms and kinetic equations of Rhodamine B removal by nZVI/rGO, it is found that the Freundlich equation and pseudo-second order kinetics can better describe the adsorption process of Rhodamine B by nZVI/rGO. The degradation effects of nZVI and nZVI/rGO on BDE-47,BDE-100,BDE-154 were studied and compared. In the primary stage of the reaction, the degradation rate of PBDEs by the two materials was faster, and the degradation rate decreased with the decrease of adsorption and reduction ability. In addition, because BDE-154 contains more bromine atoms, it is easier to degrade than BDE-47 and BDE-100, so BDE-154 not only degrades faster, but also has higher degradation rate. Through the study and analysis of the kinetic model, it is found that the degradation effect of nZVI and nZVI/rGO on PBDEs is pseudo-first-order reaction kinetics or pseudo-second-order reaction kinetics. In addition, according to the actual situation of the research group, the experimental results of PBDEs are supplemented by theoretical calculation. The B3PW91/6-311 G (d, p) and PBE/TZ2P/ZORA methods were used to optimize the structure of BDE-28,BDE-30,BDE-32,BDE-51,BDE-116 and BDE-166, and the bond lengths of C-Br and CNO were compared with their experimental values. The transition relations between BDE-7 and BDE-12 configuration transition states and anionic states were studied by QST2 method, and the dehalogenation paths of BDE-47,BDE-17,BDE-15,BDE-8,BDE-7 and BDE-4 anions under solvation condition were studied. The debromination rate constant of 14 kinds of BDE homologues was predicted by establishing a quantitative structure-activity relationship model.
【學(xué)位授予單位】：貴州師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X505;TB33
本文編號：2472593
[Abstract]:Since graphene was discovered in 2004, it has attracted people's attention because of its unique structure and properties, and has rapidly become the focus of frontier research in many disciplines. Graphene has a unique two-dimensional plane structure and large specific surface area, which makes it an ideal carrier for loading inorganic nanoparticles. At present, there have been a series of reports that graphene and functional particles are combined to prepare graphene composites. In addition, zero-valent nano-iron (nZVI) shows a very obvious advantage in environmental remediation, but there are still some problems in practical application, such as easy oxidation, easy agglomeration and high preparation cost. These limit the removal efficiency of environmental pollutants by nZVI. The preparation of graphene-supported zero-valent iron nanocomposites (nZVI/rGO) can not only inhibit the aggregation of nZVI and improve its reactivity, but also expand the potential application value of graphene in the field of environmental remediation. In this paper, the feasibility of removing organic pollutants (rhodamine B, polybrominated diphenyl ether) from nZVI/rGO composites was studied, which can provide some reference value for the practical application of nZVI/rGO. The main contents are as follows: nZVI; was prepared by liquid phase reduction method and graphite oxide (GO), was prepared by modified Hummers method. NZVI/rGO composite was prepared by using sodium borohydride as reducing agent. The prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), BET specific surface area (BET) and X-ray photoelectron spectroscopy (XPS). The removal of Rhodamine B (Rh B), by graphene-loaded zero-valent iron nanocomposites was studied by using RSM and ANN-GA modeling methods to optimize the influencing factors of Rhodamine B removal rate (initial pH, concentration, temperature and reaction time). The results show that the predicted values of the two models are in good agreement with the experimental values. Compared with the experimental values, the prediction results of the ANN-GA model are more accurate, and the initial concentration of RSM is the most important influencing factor by ANOVA. In addition, by fitting the adsorption isotherms and kinetic equations of Rhodamine B removal by nZVI/rGO, it is found that the Freundlich equation and pseudo-second order kinetics can better describe the adsorption process of Rhodamine B by nZVI/rGO. The degradation effects of nZVI and nZVI/rGO on BDE-47,BDE-100,BDE-154 were studied and compared. In the primary stage of the reaction, the degradation rate of PBDEs by the two materials was faster, and the degradation rate decreased with the decrease of adsorption and reduction ability. In addition, because BDE-154 contains more bromine atoms, it is easier to degrade than BDE-47 and BDE-100, so BDE-154 not only degrades faster, but also has higher degradation rate. Through the study and analysis of the kinetic model, it is found that the degradation effect of nZVI and nZVI/rGO on PBDEs is pseudo-first-order reaction kinetics or pseudo-second-order reaction kinetics. In addition, according to the actual situation of the research group, the experimental results of PBDEs are supplemented by theoretical calculation. The B3PW91/6-311 G (d, p) and PBE/TZ2P/ZORA methods were used to optimize the structure of BDE-28,BDE-30,BDE-32,BDE-51,BDE-116 and BDE-166, and the bond lengths of C-Br and CNO were compared with their experimental values. The transition relations between BDE-7 and BDE-12 configuration transition states and anionic states were studied by QST2 method, and the dehalogenation paths of BDE-47,BDE-17,BDE-15,BDE-8,BDE-7 and BDE-4 anions under solvation condition were studied. The debromination rate constant of 14 kinds of BDE homologues was predicted by establishing a quantitative structure-activity relationship model.
【學(xué)位授予單位】：貴州師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X505;TB33
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