本文選題：納米零價鐵 + 聚乙烯吡咯烷酮(PVP)��； 參考：《上海大學》2015年碩士論文

【摘要】：土壤是人類的重要資源,在人們的生產(chǎn)和生活中具有不可替代的作用。但是,隨著工業(yè)和經(jīng)濟的快速發(fā)展,鉻化合物被廣泛應用于各種行業(yè)(如金屬電鍍、電子、制革、冶金和木材保護)。由于含鉻廢棄物的不當堆存和含鉻廢水的亂排放,導致大量鉻尤其是Cr(VI)進入土壤中,引起嚴重的污染。Cr(VI)以其較大的毒害作用引發(fā)了一系列負面效應,影響了周圍動物,植物以及人類的健康。因此,解決土壤中Cr(VI)的污染問題成為了環(huán)境工作者關注的焦點。近幾年的研究表明,納米級零價鐵材料由于具有高的反應活性,可修復多種環(huán)境污染物等特點,成為目前環(huán)境污染修復技術(shù)中一個非�；钴S的研究領域。但是在實際應用中納米鐵材料仍然存在一些問題需要解決,如納米鐵合成條件不易控制,極易團聚,空氣穩(wěn)定性差。這些因素都對納米鐵材料的制備和使用提出了嚴峻的挑戰(zhàn)。本論文對納米鐵制備的液相還原法進行改進,制備出聚乙烯吡咯烷酮(PVP)和羧甲基纖維素(CMC)穩(wěn)定的納米鐵材料并用于土壤Cr(VI)污染的修復。論文研究了穩(wěn)定納米鐵的穩(wěn)定性,考察了穩(wěn)定納米鐵對土壤中Cr(VI)的去除能力,探討了穩(wěn)定納米鐵去除Cr(VI)的動力學和機理。通過實驗,得到如下結(jié)果:1.通過優(yōu)化制備條件得到PVP穩(wěn)定納米零價鐵制備的最佳方法,PVP投加量為0.5 g、乙醇加入量為20 m L以及Fe SO4?7H2O和Na BH4的摩爾比為1:3時,得到高反應活性的納米零價鐵。表征分析結(jié)果顯示,PVP穩(wěn)定納米零價鐵粒徑范圍為50-100 nm,并具有一定的抗氧化性能。比表面積為53 m2/g。單因素實驗結(jié)果表明,較高的PVP穩(wěn)定納米零價鐵投加量(0.4 g/L),較低的土壤Cr(VI)初始含量(138.93 mg/kg),較低的p H值(3)時,土壤中Cr(VI)的去除率最高。根據(jù)單因素的實驗結(jié)果進行正交試驗,得到土壤Cr(VI)初始含量為138.93 mg/kg,p H=5,PVP穩(wěn)定納米零價鐵投加量為0.3 g/L時為最優(yōu)條件。PVP穩(wěn)定納米零價鐵對六價鉻的還原過程符合偽一級反應動力學,表觀速率常數(shù)kobs=0.0093 min-1。研究了實際離子活度條件下基于電位-p H熱力學計算圖的六價鉻的去除機制,在酸性條件下,Fe2+、HCr O4-及Cr3+為主要存在形態(tài),有利于六價鉻還原為三價鉻,故在酸性條件下六價鉻去除率高。在堿性條件下,Cr(OH)2+、Cr(OH)2+、Cr(OH)3、Cr(OH)4-及Fe(OH)3為主要存在形態(tài),同時又有共沉淀物的產(chǎn)生,故在堿性條件下六價鉻去除率低。2.通過優(yōu)化制備條件得到CMC穩(wěn)定納米零價鐵制備的最佳方法,CMC質(zhì)量比為0.2%、CMC溶液加入量為20 m L以及Fe SO4?7H2O和Na BH4的摩爾比為1:3時,得到高反應活性的納米零價鐵。表征分析結(jié)果顯示,CMC穩(wěn)定納米零價鐵粒徑范圍為80-100 nm,并具有一定的抗氧化性能。比表面積為16 m2/g。單因素實驗結(jié)果表明,較高的CMC穩(wěn)定納米零價鐵投加量(0.6 g/L),較低的土壤Cr(VI)初始含量(138.93 mg/kg),較低的p H值(3)時,土壤中Cr(VI)的去除率最高。根據(jù)單因素的實驗結(jié)果進行正交試驗,得到土壤Cr(VI)初始含量為138.93 mg/kg,p H=5,CMC穩(wěn)定納米零價鐵投加量為0.5 g/L時為最有條件。CMC穩(wěn)定納米零價鐵對六價鉻的還原過程符合偽二級反應動力學,表觀速率常數(shù)kobs=0.0004min-1。研究了實際離子活度條件下基于電位-p H熱力學計算圖的六價鉻的去除機制,在酸性條件下,Fe2+、HCr O4-及Cr3+為主要存在形態(tài),有利于六價鉻還原為三價鉻,故在酸性條件下六價鉻去除率高。在堿性條件下,Cr(OH)2+、Cr(OH)2+、Cr(OH)3、Cr(OH)4-及Fe(OH)3為主要存在形態(tài),同時又有共沉淀物的產(chǎn)生,故在堿性條件下六價鉻去除率低。
[Abstract]:Soil is an important resource of human beings and plays an irreplaceable role in the production and life of people. However, with the rapid development of industry and economy, chromium compounds are widely used in various industries (such as metal plating, electronics, leather making, metallurgy and wood protection). Due to the improper storage of chromium containing waste and the disorderly discharge of chromium containing wastewater, A large amount of chromium, especially Cr (VI), enters the soil, causing serious pollution of.Cr (VI) causing a series of negative effects, affecting the health of the surrounding animals, plants and human beings. Therefore, the problem of solving the pollution of Cr (VI) in the soil has become the focus of environmental workers. In recent years, studies have shown that the nanoscale zero price is zero. Because of its high reactive activity and the ability to repair a variety of environmental pollutants, iron material has become a very active research field in the remediation of environmental pollution. However, in practical applications, there are still some problems to be solved in the practical application. For example, the conditions of the nano iron are difficult to be controlled, easy to be reunited, and the stability of the air is poor. These factors have challenged the preparation and use of nanomaterials. In this paper, we improved the liquid phase reduction method prepared by nano iron, prepared PVP and CMC stabilized nano iron materials and used the remediation of soil Cr (VI) pollution. The stability of stable nano iron was studied in this paper. The removal ability of Cr (VI) in soil by stable nano iron was investigated and the kinetics and mechanism of stabilizing nano iron to remove Cr (VI) was discussed. The following results were obtained by experiments. 1. by optimizing preparation conditions, the best method of preparing PVP stable nano zero valent iron was obtained, PVP dosage was 0.5 g, ethanol added to 20 m L and Fe SO4? 7H2O and Fe SO4 When the mole ratio is 1:3, the highly reactive nano zero valent iron is obtained. The results of characterization analysis show that the PVP stable nano zero valent iron particle size range is 50-100 nm and has certain antioxidant properties. The results of a single factor experiment with a specific surface area of 53 m2/g. show that the higher PVP stable nano zero valent iron dosage (0.4 g/L), the lower soil Cr (VI) at the beginning of the experiment. When the initial content (138.93 mg/kg) and low P H value (3), the removal rate of Cr (VI) in the soil is the highest. According to the experimental results of single factor, the initial content of the soil Cr (VI) is 138.93 mg/kg, P H=5, and the PVP stable nano zero valent iron addition is the optimal condition for the reduction of the six valent chromium. The pseudo first order reaction kinetics, apparent rate constant kobs=0.0093 min-1., studied the removal mechanism of six valence chromium based on the thermodynamic calculation of the potential -p H under the actual ionic activity. Under the condition of acid, Fe2+, HCr O4- and Cr3+ are the main existing forms, which are favorable for the six valence chromium to be trivalent chromium, so the removal rate of six valence chromium under the acid condition. Under alkaline conditions, Cr (OH) 2+, Cr (OH) 2+, Cr (OH) 3, Cr (OH) 4- and Fe (3) are the main existing forms, and there are co precipitates at the same time. Therefore, under alkaline conditions, the removal rate of six valence chromium is low. The optimum method for preparing stable nano zero valent iron is obtained by optimizing preparation conditions. The mass ratio is 0.2%, and the amount of solution addition is 20. When the molar ratio of SO4? 7H2O and Na BH4 is 1:3, the highly reactive nano zero valent iron is obtained. The analysis results show that the CMC stable nano zero valent iron particle size range is 80-100 nm, and has certain antioxidant properties. The higher CMC stable nano zero valent iron dosage (0.6 g/L) is lower than the surface area of 16 m2/g.. When the initial content of soil Cr (VI) (138.93 mg/kg) and low P H value (3), the removal rate of Cr (VI) in the soil is the highest. According to the experimental results of single factor, the initial content of Cr (VI) is 138.93 mg/kg, P H=5, and the stability nanoscale zero valent iron is the most conditional zero valent iron to six valence chromium. The reduction process conforms to the pseudo two stage reaction kinetics. The apparent rate constant kobs=0.0004min-1. studies the removal mechanism of six valence chromium based on the thermodynamic calculation of the potential -p H under the actual ionic activity. Under the acidic condition, Fe2+, HCr O4- and Cr3+ are the main existing forms, which are favorable for the reduction of six valence chromium to trivalent chromium, so it is under acidic conditions. The removal rate of six valence chromium is high. Under alkaline conditions, Cr (OH) 2+, Cr (OH) 2+, Cr (OH) 3, Cr (OH) 4- and Fe (3) are the main forms, and also have common precipitates, so the removal rate of six valence chromium under alkaline conditions is low.
【學位授予單位】：上海大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X53

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本文編號：1987704