本文選題：胡敏酸-赤鐵礦復合納米顆粒 + 吸附　； 參考：《浙江大學》2017年碩士論文

【摘要】：由于納米顆粒具有很小的粒徑和較大的比表面積,使得這些材料在各領(lǐng)域都有廣泛的應(yīng)用。工程納米顆粒在土壤與水體修復中已有較多應(yīng)用,然而當這些工程納米顆粒進入環(huán)境中后會對微生物、植物、動物甚至人體造成毒害作用,因此,研究人員開始將目光轉(zhuǎn)移到天然納米顆粒。土壤天然納米顆粒的產(chǎn)生伴隨著地球和人類演化的整個過程,與其所處環(huán)境更為兼容,這些納米顆粒可能具有與工程納米顆粒相似的特性,但是環(huán)境風險更小。本研究以胡敏酸包被的納米赤鐵礦為對象,開展了對典型有機污染物五氯酚(PCP)和菲(PHE)的吸附試驗,比較了不同胡敏酸種類、胡敏酸包被量以及pH條件對吸附的影響,獲得主要結(jié)果如下:(1)納米赤鐵礦經(jīng)胡敏酸包被后,其對PCP和PHE的吸附能力有1-2個數(shù)量級的提高。吸附能力與有機污染物的極性有關(guān),對極性較低的PHE的吸附分配系數(shù)要明顯高于極性高的PCP。通過傅里葉紅外光譜、13C核磁共振、元素分析等研究手段發(fā)現(xiàn),胡敏酸包被可以提高納米赤鐵礦表面的疏水性,并且引入較多的有機官能基團,為吸附提供了更多的作用方式。(2)胡敏酸-赤鐵礦復合納米顆粒對PCP和PHE的吸附能力隨著胡敏酸包被量的增加而增強。在胡敏酸包被比例相同的情況下,HApeat(Peat Humic acid)包被的納米赤鐵礦對污染物的吸附分配系數(shù)高于HAsoii(Soil humic aicid)包被的。比較有機碳標準化分配系數(shù)Koc發(fā)現(xiàn),吸附在納米赤鐵礦表面的胡敏酸對PCP和PHE的KOC要高于原胡敏酸,說明納米赤鐵礦會選擇性吸附胡敏酸中的某些組分,從而造成胡敏酸的分級作用。胡敏酸的構(gòu)象改變造成高包被量的胡敏酸-赤鐵礦復合納米顆粒的Koc要低于低包被量的復合納米顆粒。(3)溶液pH由2到12的變化過程中,胡敏酸-赤鐵礦復合納米顆粒對PCP和PHE的吸附能力都明顯降低,尤其是對PCP。疏水作用、氫鍵作用、靜電作用、胡敏酸構(gòu)象和污染物離解等可能存在機制共同造成在低pH條件下,對PCP和PHE的吸附能力最強,而在高pH條件,吸附能力最弱。低pH下增強的疏水作用、氫鍵作用等可以彌補顆粒團聚導致的吸附位點的減少。總的來說,胡敏酸的性質(zhì)變化主導著吸附的整個過程。
[Abstract]:These materials are widely used in various fields because of their small particle size and large specific surface area. Engineering nanoparticles have been widely used in soil and water remediation. However, when they enter the environment, they can cause toxicity to microorganisms, plants, animals and even human beings. The researchers began to shift their attention to natural nanoparticles. The formation of soil natural nanoparticles is accompanied by the whole evolution process of the earth and human being, which is more compatible with the environment. These nanoparticles may have similar characteristics to engineering nanoparticles, but the environmental risk is lower. In this study, Nano-hematite coated with Hu Min acid was used to study the adsorption of typical organic pollutants, pentachlorophenol (Hu Min) and phenanthrene (PHE). The effects of different kinds of Hu Min acids, the amount of Hu Min acid coating and pH on the adsorption were compared. The main results are as follows: (1) the adsorption of PCP and PHE on hematite nanocrystalline was improved by 1-2 orders of magnitude after it was coated with Hu Min acid. The adsorption capacity is related to the polarity of organic pollutants, and the adsorption partition coefficient of PHE with lower polarity is obviously higher than that of PCPs with high polarity. By means of Fourier transform infrared spectroscopy (FTIR), 13C NMR and elemental analysis, it was found that Hu Min acid coating could improve the hydrophobicity of hematite nanocrystalline surface and introduce more organic functional groups. The adsorption ability of Hu Min and hematite composite nanoparticles for PCP and PHE increased with the increase of the amount of Hu Min acid coating. Under the same Hu Min acid coating ratio, the adsorption and partition coefficients of hematite coated with Hu Min acid are higher than those coated by HAsoii(Soil humic acid. Compared with the standard partition coefficient of organic carbon (Koc), it was found that the KOC of PCP and PHE adsorbed on the surface of nano-hematite was higher than that of the original Hu Min acid, indicating that nano-hematite selectively adsorbs some components of Hu Min acid. As a result, Hu Min acid is classified. The conformational change of Hu Min acid resulted in the Koc of high encapsulated Hu Min acid-hematite composite nanoparticles being lower than that of low encapsulated Hu Min acid / hematite composite nanoparticles. The pH of the solution varied from 2 to 12. The adsorption ability of Hu Min and hematite composite nanoparticles to PCP and PHE was obviously decreased, especially for PHE. Hydrophobic interaction, hydrogen bond interaction, electrostatic interaction, Hu Min conformation and pollutant dissociation may result in the strongest adsorption capacity of PCP and PHE at low pH, but the weakest at high pH. The increase of hydrophobicity and hydrogen bonding at low pH can compensate for the decrease of adsorption sites caused by particle agglomeration. In general, the property change of Hu Min acid dominates the whole process of adsorption.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X505;O647.3

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相關(guān)博士學位論文 前2條

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相關(guān)碩士學位論文 前1條

1 曾凡鳳;天然無機納米顆粒對有機污染物的吸附作用與機理[D];浙江大學;2014年

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本文編號：1822342