發(fā)布時間：2018-06-06 02:05

  本文選題：硅藻土 + 磁分離��； 參考：《濟南大學》2017年碩士論文

【摘要】：目前,重金屬和磷酸鹽污染由于其對生態(tài)和人體的眾多不利影響,已成為全世界關注的話題之一。吸附法由于其操作的簡單性和靈活性、低廉的價格、良好的選擇性和再生能力可被用于水中重金屬和磷酸鹽的去除,而應用的關鍵在于尋找一種高效、友好、經(jīng)濟的吸附劑。硅藻土由于其低價易得、多孔性、良好的滲透性和熱穩(wěn)定性等優(yōu)點被認為是一種理想的吸附劑,但是較低的去除能力和分離的困難極大地限制了它的應用,需要尋求一些合適的方法提高硅藻土的性能,如將硅藻土與具有良好絡合能力的氨基官能團和較強超順磁性的Fe_3O_4結合在一起,將是一種理想的解決方法。首先,本文采用一步溶劑熱法將Fe_3O_4納米顆粒負載至硅藻土(diatomite,DTM)表面,合成了氨基化磁性硅藻土復合材料(Fe_3O_4/DTM),并對其進行了粉末X射線衍射(XRD)、紅外光譜(FTIR)、X射線光電子能譜(XPS)、掃描電鏡/透射電鏡/能譜(SEM/TEN/EDS)、比表面積(BET)和磁滯回歸曲線(VSM)等表征。結果表明:大量的納米Fe_3O_4微球已經(jīng)成功負載至擁有不同孔結構的圓盤狀DTM表面,介孔狀Fe_3O_4/DTM合成成功;合成材料晶型良好,功能化官能團豐富(如羥基、氨基),比表面積、孔容和孔徑較大(50.3 m2/g、0.2408 cm3/g、8.7 nm),超順磁性較強(26.89 emu/g),能夠保證Fe_3O_4/DTM的良好吸附性能和分離性能。然后,將Fe_3O_4/DTM應用于水中Pb~(2+)、Cd~(2+)和Cu~(2+)的去除,通過實驗條件的改變、動力學和等溫線模型及相關的表征手段研究了其吸附條件、性能和機理。結果表明:Fe_3O_4/DTM對于Pb~(2+)、Cd~(2+)和Cu~(2+)的吸附能力相比于DTM有了極大的提高,20 min時便可達到吸附平衡,受溶液中Na+、K+、Mg~(2+)、Ca~(2+)等的影響較小。吸附動力學符合擬二級動力學,內部擴散階段主導著整個過程的反應速率;吸附等溫線符合Langmuir和Temkin模型,是一個易進行的均相單層的化學吸附過程,最大理論吸附量分別為51.65、42.17和7.12 mg/g。Zeta電位和XPS表征證實Fe_3O_4/DTM主要通過靜電作用、表面絡合和離子交換作用實現(xiàn)對Pb~(2+)、Cd~(2+)和Cu~(2+)的去除。此外,在吸附后吸附劑Fe_3O_4/DTM在磁場作用下可實現(xiàn)快速分離,并且吸附質在酸處理后可得到回收。最后,將Fe_3O_4/DTM應用于水中磷酸鹽的去除,詳細研究了Fe_3O_4/DTM吸附磷酸鹽的最優(yōu)條件、性能及機理。結果表明:Fe_3O_4/DTM對磷酸鹽的吸附在30 min時便可達到平衡,吸附過程受溶液pH值的影響,酸性條件下效果較好并且吸附后溶液pH值穩(wěn)定在8左右。吸附動力學和吸附等溫線分別符合擬二級動力學和Langmuir模型,內部擴散階段主導著整個過程的反應速率,最大理論吸附容量為11.89 mg/g。吸附機理為靜電吸引和配體交換。綜上所述,Fe_3O_4/DTM很容易由低廉豐富的硅藻土合成,合成的材料擁有優(yōu)秀的吸附、再生和分離性能,是一個良好的重金屬和磷酸鹽吸附劑,展現(xiàn)出良好的應用前景。
[Abstract]:At present, heavy metal and phosphate pollution has become one of the topics of worldwide concern because of its many adverse effects on ecology and human body. The adsorption method can be used to remove heavy metals and phosphate in water because of its simplicity and flexibility, low price, good selectivity and regeneration ability. The key to its application is to find an efficient, friendly and economical adsorbent. Diatomite is considered to be an ideal adsorbent because of its advantages of low price, porosity, good permeability and thermal stability, but its application is greatly limited by its low removal capacity and separation difficulties. It is necessary to find some suitable ways to improve the properties of diatomite, such as combining diatomite with amino functional groups with good complexing ability and strong superparamagnetic Fe_3O_4, which is an ideal solution. Firstly, Fe_3O_4 nanoparticles were loaded onto diatomite Fe_3O_4 surface by one-step solvothermal method. The Amino magnetic diatomite composite was synthesized and characterized by powder X-ray diffraction (XRD), infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) / transmission electron microscopy (TEM) / energy dispersive electron microscopy (EDS), specific surface area (BET) and hysteresis regression curve (VSM). The results show that a large number of nanocrystalline Fe_3O_4 microspheres have been successfully loaded to the disk DTM surface with different pore structures, and mesoporous Fe_3O_4/DTM has been synthesized successfully, and the synthesized materials have good crystal form and abundant functionalized functional groups (such as hydroxyl, amino acid, specific surface area, etc.) The pore volume and pore size of 50.3 m ~ 2 / g ~ (-1) 0.2408 cm ~ (-3) / g ~ (8.7) nm ~ (-1), with a strong superparamagnetism of 26.89 emu / g ~ (-1), can guarantee the good adsorption and separation performance of Fe_3O_4/DTM. Then, Fe_3O_4/DTM was applied to the removal of Pb~(2 and Cu~(2 in water. The adsorption conditions, properties and mechanism were studied by the change of experimental conditions, kinetics, isotherm model and related characterization methods. The results show that the adsorptive capacity of Fe3O / DTM for Pb~(2 and Cu~(2) can reach equilibrium when compared with that of DTM for 20 min, and is less affected by Na ~ (3) K ~ (2) mg ~ (2) ~ (2) ~ (+) ~ (2) ~ (2). The adsorption kinetics accords with the pseudo-second-order kinetics, the internal diffusion stage dominates the reaction rate of the whole process, and the adsorption isotherm accords with the Langmuir and Temkin models, which is a homogeneous monolayer chemisorption process. The maximum theoretical adsorption amounts were 51.65N 42.17 and 7.12 mg/g.Zeta potential and XPS characterization, respectively. The results show that the removal of Pb~(2 and Cu~(2 by Fe_3O_4/DTM is mainly achieved by electrostatic interaction, surface complexation and ion exchange. In addition, the adsorbent Fe_3O_4/DTM can be separated rapidly under the action of magnetic field after adsorption, and the adsorbate can be recovered after acid treatment. Finally, Fe_3O_4/DTM was applied to the removal of phosphate in water, and the optimum conditions, properties and mechanism of phosphate adsorption by Fe_3O_4/DTM were studied in detail. The results show that the adsorption of phosphate by 10% Fe3ODTM can reach equilibrium at 30 min. The adsorption process is affected by pH value of solution, and the pH value of solution is stable at about 8 after adsorption under acidic condition. The adsorption kinetics and adsorption isotherm accord with pseudo-second-order kinetics and Langmuir model respectively. The internal diffusion stage dominates the reaction rate of the whole process and the maximum theoretical adsorption capacity is 11.89 mg / g. The adsorption mechanism is electrostatic attraction and ligand exchange. To sum up, it is very easy to synthesize Fe3O4 / DTM from cheap and abundant diatomite. The synthesized material has excellent adsorption, regeneration and separation properties. It is a good adsorbent for heavy metals and phosphate, and has a good application prospect.
【學位授予單位】：濟南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X52

【參考文獻】

中國期刊全文數(shù)據(jù)庫 前3條

1 鄭瑩;潘楊;周曉華;廖p芎，

本文編號：1984509