粘土礦物強(qiáng)化零價(jià)鐵去除廢水中重金屬污染物的作用研究
發(fā)布時(shí)間：2018-10-23 12:41
【摘要】：零價(jià)鐵作為活性介質(zhì)的可滲透反應(yīng)墻(Fe0-PRB),被認(rèn)為是一種能替代傳統(tǒng)抽取處理、最具發(fā)展?jié)摿Φ脑恍迯?fù)地下水技術(shù),但在修復(fù)過(guò)程中零價(jià)鐵反應(yīng)活性的降低和滲透能力的減弱,是影響Fe0-PRB使用壽命、制約其實(shí)際應(yīng)用的最重要因素。本文選擇兩種重金屬離子(陰離子Se O42-(Se(VI)和陽(yáng)離子Pb2+)作目標(biāo)污染物,用連續(xù)柱試驗(yàn)方法模擬Fe0-PRB技術(shù),將對(duì)其具有較強(qiáng)吸附作用的荷正電性的改性膨潤(rùn)土—羥基鋁柱撐膨潤(rùn)土(Al-bent)和三種荷負(fù)電性的天然粘土礦物(海泡石:Sepiolite,鈣基膨潤(rùn)土:Ca-bent,高嶺土:Kaoline)分別與鐵粉、砂均勻混合,用作PRB中的混合活性材料,比較研究了各種粘土對(duì)Fe0-PRB去除重金屬污染物的強(qiáng)化作用和地下水中常見(jiàn)共存組分(腐殖酸(HA)和四種陰離子(Cl-、NO3-、HCO3-和SO42-))對(duì)Se O42-去除作用的影響;結(jié)合同步輻射X-射線(xiàn)吸收精細(xì)結(jié)構(gòu)X-ray Absorption Fine Stucture,XAFS)光譜技術(shù)和X-射線(xiàn)衍射儀(Xray diffraction,XRD)等現(xiàn)代分析方法考察粘土在Fe0-PRB去除重金屬污染物的協(xié)同作用機(jī)制。主要結(jié)果如下:1.對(duì)Se O42-具有良好吸附作用的Al-bent與Fe0、砂混合得到的Fe0/Al-bent/砂反應(yīng)體系對(duì)Se O42-的還原去除能力明顯高于Fe0/砂,也遠(yuǎn)高于Fe0/砂與Al-bent/砂體系對(duì)Se O42-去除率的加和,顯示Al-bent和Fe0之間存在明顯的協(xié)同效應(yīng)。其協(xié)同作用主要源于:Al-bent加入使Se O42-在Fe0表面得到富集,促進(jìn)了兩者之間的電子轉(zhuǎn)移,從而增強(qiáng)了Fe0的還原能力;表面富含的Si-OH,Al-OH的Al-bent能夠緩沖反應(yīng)介質(zhì)的p H,從而可減少鐵表面的腐蝕產(chǎn)物;鐵表面的腐蝕產(chǎn)物還能轉(zhuǎn)移到Al-bent,從而延長(zhǎng)鐵的反應(yīng)壽命。此外,XAFS測(cè)定結(jié)果表明Al-bent的加入能有效促進(jìn)Fe0將Se(VI)還原成溶解性更低,毒性更小的Se(-II)或Se(0)。2.腐殖酸(HA)和常見(jiàn)的共存陰離子(Cl-、NO3-、HCO3-和SO42-)均能降低Fe0/Al-bent/砂和Fe0/砂對(duì)Se(VI)的去除率,但由于Al-bent對(duì)這些共存物質(zhì)較強(qiáng)的吸附作用,因而可明顯弱化這種抑制效應(yīng)。3.將三種天然粘土礦物分別與Fe0、砂均勻混合,均能顯著提高對(duì)合成廢水中Pb2+的去除能力,去除率與相應(yīng)粘土吸附Pb2+的能力成正相關(guān),即:Sepiolite/Fe0/砂Ca-bent/Fe0/砂Kaoline/Fe0/砂Fe0/砂。
[Abstract]:The permeable reactive wall (Fe0-PRB) of zero-valent iron as an active medium is considered as an in situ remediation technology which can replace the traditional extraction treatment and has the most potential development. However, in the process of remediation, the activity of zero-valent iron reaction decreases and the permeability decreases. It is the most important factor that affects the service life of Fe0-PRB and restricts its practical application. In this paper, two kinds of heavy metal ions (anionic Se O42-( Se (VI) and cationic Pb2) were selected as target pollutants, and Fe0-PRB technique was simulated by continuous column test. The positively charged modified bentonite (Al-bent) and three kinds of natural clay minerals (sepiolite: Sepiolite, calcium-based bentonite: Ca-bent, kaolin), which have strong adsorption effect, were mixed with iron powder and sand, respectively, and three kinds of natural clay minerals (sepiolite: Sepiolite, calcium bentonite: Ca-bent, kaolin) were mixed with iron powder and sand. As a mixed active material in PRB, the enhancement effect of various clay on the removal of heavy metal pollutants by Fe0-PRB and the effects of common coexisting components (HA) humic acid and four anions (Cl-,NO3-,HCO3- and SO42-) on Se O 42-removal in groundwater were compared. Combined with synchrotron radiation X-ray absorption fine structure (X-ray Absorption Fine Stucture,XAFS) spectroscopy and X-ray diffractometer (Xray diffraction,XRD), the synergistic mechanism of removing heavy metal pollutants from clay in Fe0-PRB was investigated. The main results are as follows: 1. The reduction ability of Se O 42- by Fe0/Al-bent/ sand reaction system with good adsorption of Se O 42- and Fe0, sand was significantly higher than that of Fe0/ sand, and the addition of Fe0/ sand and Al-bent/ sand system to Se O 42-removal rate was much higher than that of Fe0/ sand and Al-bent/ sand system, and the removal rate of Se O 42- was much higher than that of Fe0/ sand and Al-bent/ sand system. There is obvious synergistic effect between Al-bent and Fe0. The synergistic effect is mainly due to the fact that the addition of Al-bent enriches Se O42- on the surface of Fe0 and promotes the electron transfer between them, thus enhancing the reduction ability of Fe0. The Al-bent rich in Si-OH,Al-OH on the surface can buffer the pH of the reaction medium, thus reducing the corrosion products on the surface of iron, and the corrosion products on the surface of iron can also be transferred to Al-bent, thus prolonging the reaction life of iron. In addition, XAFS results showed that the addition of Al-bent could effectively promote the reduction of Se (VI) by Fe0 to Se (- II) or Se (0). 2 with lower solubility and less toxicity. Both humic acid (HA) and common coexisting anions (Cl-,NO3-,HCO3- and SO42-) can reduce the removal rate of Se (VI) from Fe0/Al-bent/ sand and Fe0/ sand, but the inhibition effect can be weakened obviously because of the strong adsorption effect of Al-bent on these coexisting compounds. When three kinds of natural clay minerals were mixed with Fe0, sand uniformly, the removal rate of Pb2 in synthetic wastewater was significantly improved, and the removal rate was positively correlated with the ability of corresponding clay to adsorb Pb2, that is, Sepiolite/Fe0/ sand, Ca-bent/Fe0/ sand, Kaoline/Fe0/ sand, Fe0/ sand.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：O647.3;X703
本文編號(hào)：2289271
[Abstract]:The permeable reactive wall (Fe0-PRB) of zero-valent iron as an active medium is considered as an in situ remediation technology which can replace the traditional extraction treatment and has the most potential development. However, in the process of remediation, the activity of zero-valent iron reaction decreases and the permeability decreases. It is the most important factor that affects the service life of Fe0-PRB and restricts its practical application. In this paper, two kinds of heavy metal ions (anionic Se O42-( Se (VI) and cationic Pb2) were selected as target pollutants, and Fe0-PRB technique was simulated by continuous column test. The positively charged modified bentonite (Al-bent) and three kinds of natural clay minerals (sepiolite: Sepiolite, calcium-based bentonite: Ca-bent, kaolin), which have strong adsorption effect, were mixed with iron powder and sand, respectively, and three kinds of natural clay minerals (sepiolite: Sepiolite, calcium bentonite: Ca-bent, kaolin) were mixed with iron powder and sand. As a mixed active material in PRB, the enhancement effect of various clay on the removal of heavy metal pollutants by Fe0-PRB and the effects of common coexisting components (HA) humic acid and four anions (Cl-,NO3-,HCO3- and SO42-) on Se O 42-removal in groundwater were compared. Combined with synchrotron radiation X-ray absorption fine structure (X-ray Absorption Fine Stucture,XAFS) spectroscopy and X-ray diffractometer (Xray diffraction,XRD), the synergistic mechanism of removing heavy metal pollutants from clay in Fe0-PRB was investigated. The main results are as follows: 1. The reduction ability of Se O 42- by Fe0/Al-bent/ sand reaction system with good adsorption of Se O 42- and Fe0, sand was significantly higher than that of Fe0/ sand, and the addition of Fe0/ sand and Al-bent/ sand system to Se O 42-removal rate was much higher than that of Fe0/ sand and Al-bent/ sand system, and the removal rate of Se O 42- was much higher than that of Fe0/ sand and Al-bent/ sand system. There is obvious synergistic effect between Al-bent and Fe0. The synergistic effect is mainly due to the fact that the addition of Al-bent enriches Se O42- on the surface of Fe0 and promotes the electron transfer between them, thus enhancing the reduction ability of Fe0. The Al-bent rich in Si-OH,Al-OH on the surface can buffer the pH of the reaction medium, thus reducing the corrosion products on the surface of iron, and the corrosion products on the surface of iron can also be transferred to Al-bent, thus prolonging the reaction life of iron. In addition, XAFS results showed that the addition of Al-bent could effectively promote the reduction of Se (VI) by Fe0 to Se (- II) or Se (0). 2 with lower solubility and less toxicity. Both humic acid (HA) and common coexisting anions (Cl-,NO3-,HCO3- and SO42-) can reduce the removal rate of Se (VI) from Fe0/Al-bent/ sand and Fe0/ sand, but the inhibition effect can be weakened obviously because of the strong adsorption effect of Al-bent on these coexisting compounds. When three kinds of natural clay minerals were mixed with Fe0, sand uniformly, the removal rate of Pb2 in synthetic wastewater was significantly improved, and the removal rate was positively correlated with the ability of corresponding clay to adsorb Pb2, that is, Sepiolite/Fe0/ sand, Ca-bent/Fe0/ sand, Kaoline/Fe0/ sand, Fe0/ sand.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：O647.3;X703
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 賈廣寧;重金屬污染的危害與防治[J];有色礦冶;2004年01期
，本文編號(hào)：2289271
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