本文選題：水鐵礦 + 砷�。� 參考：《合肥工業(yè)大學(xué)》2015年碩士論文

【摘要】：由于具有高比表面積和良好的陰、陽(yáng)離子固持性能,水鐵礦(Fe5HO8·4H2O)作為一種高效環(huán)境材料受到廣泛關(guān)注,其中一個(gè)重要應(yīng)用方向就是運(yùn)用水鐵礦處理含As水體,但是水鐵礦的低穩(wěn)定性在一定程度上限制了其應(yīng)用。本文擬通過(guò)改變水鐵礦的合成速率和As含量各異的水鐵礦,來(lái)制得不同As含量和結(jié)晶程度的水鐵礦,藉此探討了水鐵礦生成動(dòng)力學(xué)對(duì)其礦物學(xué)特征和對(duì)As固定能力的影響；同時(shí),開(kāi)展含砷水鐵礦在自然條件下的老化實(shí)驗(yàn)和在厭氧微生物異化鐵還原細(xì)菌(DIRB)作用下的還原分解實(shí)驗(yàn),探討水鐵礦的生成條件(動(dòng)力學(xué)和As添加量)對(duì)其轉(zhuǎn)化和分解的影響。研究對(duì)深化水鐵礦礦物學(xué)理論及優(yōu)化水鐵礦的環(huán)境工程應(yīng)用條件等方面有比較重要的意義。水鐵礦合成實(shí)驗(yàn)結(jié)果表明,低的OH-添加速率會(huì)導(dǎo)致Fe(OH)x(3-x)+基團(tuán)聚合、脫水并生成與Fe連接的橋氧鍵,橋氧鍵的存在使得具有一定結(jié)晶度的6L-Fh、針鐵礦和赤鐵礦可以直接從溶液中沉淀。H2AsO4-會(huì)替代OH-的功能,但由于二者理化性質(zhì)方面的差異,As參與下形成的水鐵礦結(jié)晶度降低。中性條件下水鐵礦的老化為固相轉(zhuǎn)化,結(jié)晶度越好的初始產(chǎn)物轉(zhuǎn)化越徹底。生成速率越慢、As添加量越少的水鐵礦中的結(jié)晶程度越好,表現(xiàn)在6L-Fh越多。自然老化實(shí)驗(yàn)結(jié)果表明,中性條件下水鐵礦通過(guò)固相轉(zhuǎn)變向其它礦物轉(zhuǎn)化,生成速率越慢、As添加量越少、結(jié)晶度越好的水鐵礦轉(zhuǎn)化越快。轉(zhuǎn)化產(chǎn)物主要為針鐵礦和赤鐵礦,粒徑隨著As添加量的減少和合成時(shí)間的延長(zhǎng)而從5nm～20nm變化。含As水鐵礦轉(zhuǎn)化過(guò)程中會(huì)導(dǎo)致少量As釋放,As的釋放量受合成過(guò)程中As添加量影響較小,受生成速率影響較大,生成速率越慢,As釋放量越小。微生物實(shí)驗(yàn)結(jié)果表明,DIRB的能夠有效溶解水鐵礦,當(dāng)水鐵礦表面的吸附節(jié)點(diǎn)不足以固持As時(shí),As就會(huì)釋放進(jìn)入溶液中；生成速率對(duì)水鐵礦的結(jié)晶程度影響很大,生成速率越慢,水鐵礦結(jié)晶度越高,分解速率越慢,As釋放量越少；As添加量越高,水鐵礦結(jié)晶度越差,分解速率越快,As釋放量也越多。該研究表明,環(huán)境工程中應(yīng)用水鐵礦共沉淀法處理含As廢水時(shí),適當(dāng)降低共沉淀速率并保持水鐵礦處于氧化條件下有助于強(qiáng)化As的固定和抑制水鐵礦轉(zhuǎn)化或分解過(guò)程中As的釋放。
[Abstract]:Because of its high specific surface area, good cation fixation and high specific surface area, water ore Fe5HO84H _ 2O has attracted wide attention as a kind of efficient environmental material. One of the important application directions is to use water ore to treat as water body. But the low stability of water ore restricts its application to some extent. In this paper, the hydrothermal ore with different as content and different synthesis rate is prepared by changing the synthesis rate and the content of as, and the effect of hydrothermal formation kinetics on its mineralogical characteristics and as fixation ability is discussed. At the same time, the aging experiments of arsenic-containing water ore under natural conditions and the reduction and decomposition experiments under the action of anaerobic microorganism dissimilatory iron reducing bacteria (DIRB) were carried out. The effects of the formation conditions (kinetics and as addition) of hydrothermal ore on its transformation and decomposition are discussed. The study is of great significance in deepening the mineralogical theory of water ore and optimizing the environmental engineering application conditions of water ore. The experimental results of hydrothermal synthesis show that the low OH- addition rate leads to the polymerization, dehydration and formation of bridged oxygen bonds connected with Fe. Because of the existence of bridging oxygen bond, the crystallinity of 6L-Fh with a certain degree of crystallinity can be replaced by the precipitation of goethite and hematite directly from the solution. However, the crystallinity of water ore formed with the participation of as is decreased due to the difference of their physical and chemical properties. The aging of iron ore in neutral condition is solid phase transformation, and the better the crystallinity of the initial product is, the more thorough the transformation is. The higher the rate of formation, the better the degree of crystallization in the pyrite with less addition of as, and the more 6L-Fh. The results of natural aging test show that the slower the formation rate of iron ore is, the less the amount of as is added, and the faster the transformation of hydrothermal ore with better crystallinity can be achieved by the transformation of iron ore into other minerals through solid phase transformation under neutral conditions. The transformation products are mainly goethite and hematite. The particle size changes from 5nm~20nm with the decrease of as addition and the prolongation of synthesis time. In the process of transformation, the amount of as released from as is less affected by the amount of as added in the process of synthesis, but by the rate of formation, and the slower the rate of formation is, the smaller the release of as is. The results of microbial experiments show that DIRB can dissolve water ore effectively, and when the adsorption node on the surface of water ore is not enough to hold as, it will release as into the solution, and the rate of formation has a great influence on the crystallization degree of water ore, and the rate of formation is slower. The higher the crystallinity, the slower the decomposition rate is, and the lower the amount of as is added, the worse the crystallinity is, and the faster the decomposition rate is, the more as released. The results show that the coprecipitation method of water and iron ore in environmental engineering is used to treat wastewater containing as. Decreasing the coprecipitation rate and keeping the water ore in the oxidation condition can help to strengthen the fixation of as and inhibit the release of as during the process of transformation or decomposition.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X703;P579

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