纳米乳化油制备及其在多孔介质中的迁移释放模拟实验

发布时间：2018-04-04 07:18

本文选题：纳米乳化油　切入点：原位修复　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：乳化油作为缓释碳源在原位修复地下水硝酸盐、高氯酸盐、六价铬、卤代烃等污染方面已取得了良好的效果。但是由于乳化油存在粒径较大,粘度较高等特点,将其注入含水层进行污染修复时,易造成含水层渗透性不同程度的损失,受污染的地下水流易产生绕流现象,导致修复效率降低或者失效。为有效解决这一问题,本文借鉴食品医药领域的技术方法,引入混合乳化剂,采用升温相转化手段,制备纳米乳化油,并采用一维柱实验,模拟研究了普通乳化油及纳米乳化油在多孔介质中的迁移释放特征,对比分析了渗透性损失、乳化油碳源释放、及有效寿命等问题。论文取得主要成果如下:⑴复配实验结果表明,吐温80与斯盘80复配比例为7:3,剂油比为1:2、1:1.5、1:1,内相含量为15%~25%、10~30%、5%~35%,相转变温度为55℃条件下可制备得到纳米乳化油。其中,最佳纳米乳化油配比为:剂油比为1:1,内相含量30%。该配比下的纳米乳化油平均粒径255.1nm,稳定性动力学指数为0.5,粘度为3.72*10-4Pa·s,COD释放量为472g/L。⑵柱实验结果表明,中砂介质中纳米和微米乳化油所导致的渗透性损失分别为3.20%和20.40%,乳化油截留量分别为20.15%和28.51%。可见,乳化油截留是多孔介质渗透性损失的重要原因,乳化油油滴粒径的减小可有效缓解多孔介质的渗透性损失。此外,乳化油在多孔介质中的截留和渗透性损失也会影响到其在多孔介质中的迁移距离,微米乳化油和纳米乳化油在中砂迁移距离分别为6.53m和8.19m。相比之下,纳米乳化油在细砂介质中渗透性损失为10.70%,截留量为25.71%,迁移距离为7.36m,说明可适用的介质范围更广。⑶乳化油内相含量和粒径大小是影响COD释放比率的重要因素。实验结果表明,中砂介质中,纳米与微米乳化油溶解性COD与总COD释放比率分别为61.95%和87.61%,有效寿命分别为243.17和98.80天。尽管纳米乳化油有效寿命小于微米乳化油,但COD释放比率低于微米乳化油,释放效果更佳,且相对于堵塞问题,纳米乳化油更可接受。纳米乳化油注入细砂时,溶解性COD与总COD释放比率为77.23%,有效寿命为197.41d,表明细颗粒介质中,纳米乳化油有效寿命可得到有效延长。
[Abstract]:Emulsified oil as a slow release carbon source has achieved good results in in situ remediation of nitrate, perchlorate, hexavalent chromium and halogenated hydrocarbons in groundwater.However, because the emulsified oil has the characteristics of large particle size and high viscosity, when injected into the aquifer for pollution restoration, it is easy to cause the loss of aquifer permeability in varying degrees, and the polluted groundwater flow is easy to produce the phenomenon of flow around the aquifer.Causes repair efficiency to decrease or fail.In order to solve this problem effectively, this paper draws lessons from the technical methods in the field of food and medicine, introduces the mixed emulsifier, adopts the method of temperature rise phase conversion to prepare the nanometer emulsified oil, and adopts the one-dimensional column experiment.The characteristics of migration and release of common emulsified oil and nanometer emulsified oil in porous media were studied and the problems of permeability loss carbon source release and effective life of emulsified oil were compared and analyzed.The optimum ratio of nano-emulsified oil is 1: 1, and the content of inner phase is 30%.The average particle size of nanometer emulsified oil at this ratio is 255.1 nm, the kinetic index of stability is 0.5, and the viscosity of the emulsified oil is released by 472g/L.2 column. The results show that the average particle size of the emulsified oil is 255.1 nm.The permeability loss caused by nanometer and micron emulsified oil in medium sand medium is 3.20% and 20.40%, and the rejection of emulsified oil is 20.15% and 28.51%, respectively.It can be seen that emulsified oil retention is an important reason for the loss of permeability of porous media, and the decrease of oil droplet size can effectively alleviate the loss of permeability of porous media.In addition, the retention and permeability loss of emulsified oil in porous media also affect its migration distance in porous media. The migration distances of micron emulsified oil and nanometer emulsified oil in medium sand are 6.53m and 8.19mrespectively.In contrast, the loss of permeability, interception and migration distance of nano-emulsified oil in fine sand medium are 10.70, 25.71 and 7.36 m, respectively, indicating that the content of phase and particle size of emulsified oil in a wider range of suitable media are the important factors affecting the release ratio of COD.The results show that the ratio of soluble COD to total COD in sand medium is 61.95% and 87.61, respectively, and the effective life is 243.17 days and 98.80 days respectively.Although the effective life of nanometer emulsified oil is smaller than that of micron emulsified oil, the release ratio of COD is lower than that of micron emulsified oil, and the release effect is better than that of micron emulsified oil, and the nanometer emulsified oil is more acceptable than the plugging problem.When nano-emulsified oil was injected into fine sand, the ratio of soluble COD to total COD release was 77.23 and the effective life was 197.41 days, which indicated that the effective life of nano-emulsified oil could be effectively prolonged in fine particle medium.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X523

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