双载体乳化液膜分离浓盐水中的钙镁离子
发布时间：2018-07-16 17:24
【摘要】：海水淡化过程产生的浓盐水中含有大量钙镁离子,直接排放不仅会对周边环境造成污染,也是海洋资源的浪费。由于钙镁离子物化性质十分相似,目前的分离技术尚不能将二者有效分离。而被视为高效分离手段的乳化液膜技术,由于选择性高、传质速度快等优点,在金属离子分离领域得到广泛关注。本文提出以二(2-乙基己基)磷酸酯(D2EHPA)和二苯并-18-冠醚-6(DB18C6)作为流动载体,利用二者对钙镁离子的选择性,构建一种双载体乳化液体系,协同分离浓盐水中的两种离子,验证多因素下的双载体乳化液对两种离子的分离性能。通过对乳化液破乳率及对钙镁离子分离能力的初步考察,本论文选择二氯甲烷为油相,草酸钠溶液为内水相。以乳化液的黏度变化和破乳率为衡量稳定性的标准,考察了油水比和表面活性剂含量、内水相浓度和两种载体对于乳化液稳定性的影响。结果表明：随着油水比降低,乳化液破乳率增加,同时间段内黏度变化增大,油水比为1：1的乳化液30 min内黏度降低23 mPa·s,破乳率仅有0.45%。表面活性剂含量越高,破乳率越小,乳化液稳定性越好。乳化液稳定性随内水相Na2C2O4浓度减小而升高,破乳率由2.5%(0.2M Na2C2O4)降为1.7%(0.18M Na2C2O4)。较二苯并-18-冠醚-6,二(2-乙基己基)磷酸酯为载体的乳化液破乳率稍升高0.8%,但对整个萃取过程无明显影响。得到优化的乳化液稳定条件：油相为二氯甲烷、油水比为1:1、Span80含量为6%,内水相Na2C2O4溶液为0.18mol/L、4%D2EHPA、0.015 mol/L DB18C6。分析D2EHPA和DB18C6分别为单载体以及共同作为双载体时,两种乳化液体系对钙镁离子的萃取分离效果。D2EHPA为载体的乳化液对钙离子的最高萃取率为92.12%,DB18C6为载体的乳化液萃取钙离子效率为66.72%。双载体乳液3 min后协同分离钙离子的效率达到70%以上,30 min时达到99.38%,双载体协萃因子达到11以上,而镁离子仅有17.89%且协萃因子低于0.7,基本将钙离子完全分离。该优化结果下的操作条件：将外水相pH调至9.5,乳液组成为：90% CH2Cl2、6%Span80、4% D2EHPA、 0.017mol/L DB18C6、0.18 mol·L-1Na2C2O4、1：2油水比。
[Abstract]:The concentrated salt water produced by seawater desalination process contains a large amount of calcium and magnesium ions. Direct discharge will not only pollute the surrounding environment but also waste marine resources. Because the physicochemical properties of calcium and magnesium ions are very similar, the current separation technology can not separate them effectively. Because of its high selectivity and high mass transfer rate, the emulsion membrane technology, which is regarded as an efficient separation method, has attracted wide attention in the field of metal ion separation. In this paper, a two-carrier emulsion system was constructed using di (2-ethylhexyl) phosphate (D2EHPA) and dibenzo-18-crown-ether -6 (DB18C6) as mobile carriers. The separation performance of two kinds of ions was verified by double carrier emulsion under multiple factors. In this paper, dichloromethane was selected as oil phase and sodium oxalate solution as internal water phase through preliminary investigation of emulsion demulsification rate and separation ability of calcium and magnesium ions. The effects of oil / water ratio, surfactant content, internal water concentration and two kinds of carriers on the stability of emulsion were investigated according to the viscosity change and demulsification rate of emulsion. The results showed that the demulsification rate of the emulsion increased with the decrease of oil-water ratio, and the viscosity of the emulsion increased in the same time period. The viscosity of the emulsion with oil / water ratio of 1:1 in 30 min decreased by 23 MPA SPA, and the demulsification rate was only 0.45%. The higher the surfactant content, the smaller the demulsification rate and the better the stability of emulsion. The stability of the emulsion increased with the decrease of the concentration of Na _ 2C _ 2O _ 4, and the demulsification rate decreased from 2.5% (0.2M Na _ 2C _ 2O _ 4) to 1.7% (0.18m Na _ 2C _ 2O _ 4). Compared with dibenzo-18-crown ether -6, the emulsion demulsification rate of bis (2-ethylhexyl) phosphate was slightly higher than that of dibenzo-18-crown-ether -6, but the emulsion demulsification rate was slightly higher than that of dibenzo-18-crown ether -6, but had no obvious effect on the whole extraction process. The optimized conditions of emulsion stability are as follows: the oil phase is dichloromethane, the oil-water ratio is 1: 1, the Span80 content is 6 and the internal water phase Na2C2O4 solution is 0.18 mol / L EHPA-0.015 mol / L DB18C6. When D2EHPA and DB18C6 are single carrier and double carrier respectively, the extraction and separation effect of the two emulsions on calcium and magnesium ions. The highest extraction rate of calcium ion by emulsion of D2EHPA and DB18C6 is 92.12 and DB18C6 respectively. The extraction efficiency of calcium ion is 66.72 when the emulsion of D2EHPA and DB18C6 is the carrier. After 3 min, the synergistic separation efficiency of Ca ~ (2 +) and mg ~ (2 +) was 99.38 and 17.89%, respectively, and that of mg ~ (2 +) was only 17.89% and less than 0.7 after 30 min. The calcium ion was separated completely. The optimum operating conditions were as follows: the pH of the external water phase was adjusted to 9.5, the emulsion composition was: 1: 90% Ch _ 2Cl _ 2C _ 2 / 6Span804% D _ 2EHPA, 0.017 mol / L DB18C _ 6n 0.18 mol L ~ (-1) Na _ 2C _ 2O _ 4: 1: 2 oil-water ratio.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.8;X703
本文编号：2127087
[Abstract]:The concentrated salt water produced by seawater desalination process contains a large amount of calcium and magnesium ions. Direct discharge will not only pollute the surrounding environment but also waste marine resources. Because the physicochemical properties of calcium and magnesium ions are very similar, the current separation technology can not separate them effectively. Because of its high selectivity and high mass transfer rate, the emulsion membrane technology, which is regarded as an efficient separation method, has attracted wide attention in the field of metal ion separation. In this paper, a two-carrier emulsion system was constructed using di (2-ethylhexyl) phosphate (D2EHPA) and dibenzo-18-crown-ether -6 (DB18C6) as mobile carriers. The separation performance of two kinds of ions was verified by double carrier emulsion under multiple factors. In this paper, dichloromethane was selected as oil phase and sodium oxalate solution as internal water phase through preliminary investigation of emulsion demulsification rate and separation ability of calcium and magnesium ions. The effects of oil / water ratio, surfactant content, internal water concentration and two kinds of carriers on the stability of emulsion were investigated according to the viscosity change and demulsification rate of emulsion. The results showed that the demulsification rate of the emulsion increased with the decrease of oil-water ratio, and the viscosity of the emulsion increased in the same time period. The viscosity of the emulsion with oil / water ratio of 1:1 in 30 min decreased by 23 MPA SPA, and the demulsification rate was only 0.45%. The higher the surfactant content, the smaller the demulsification rate and the better the stability of emulsion. The stability of the emulsion increased with the decrease of the concentration of Na _ 2C _ 2O _ 4, and the demulsification rate decreased from 2.5% (0.2M Na _ 2C _ 2O _ 4) to 1.7% (0.18m Na _ 2C _ 2O _ 4). Compared with dibenzo-18-crown ether -6, the emulsion demulsification rate of bis (2-ethylhexyl) phosphate was slightly higher than that of dibenzo-18-crown-ether -6, but the emulsion demulsification rate was slightly higher than that of dibenzo-18-crown ether -6, but had no obvious effect on the whole extraction process. The optimized conditions of emulsion stability are as follows: the oil phase is dichloromethane, the oil-water ratio is 1: 1, the Span80 content is 6 and the internal water phase Na2C2O4 solution is 0.18 mol / L EHPA-0.015 mol / L DB18C6. When D2EHPA and DB18C6 are single carrier and double carrier respectively, the extraction and separation effect of the two emulsions on calcium and magnesium ions. The highest extraction rate of calcium ion by emulsion of D2EHPA and DB18C6 is 92.12 and DB18C6 respectively. The extraction efficiency of calcium ion is 66.72 when the emulsion of D2EHPA and DB18C6 is the carrier. After 3 min, the synergistic separation efficiency of Ca ~ (2 +) and mg ~ (2 +) was 99.38 and 17.89%, respectively, and that of mg ~ (2 +) was only 17.89% and less than 0.7 after 30 min. The calcium ion was separated completely. The optimum operating conditions were as follows: the pH of the external water phase was adjusted to 9.5, the emulsion composition was: 1: 90% Ch _ 2Cl _ 2C _ 2 / 6Span804% D _ 2EHPA, 0.017 mol / L DB18C _ 6n 0.18 mol L ~ (-1) Na _ 2C _ 2O _ 4: 1: 2 oil-water ratio.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.8;X703
【参考文献】
相关期刊论文 前2条
1 袁俊生;纪志永;陈建新;;海水化学资源利用技术的进展[J];化学工业与工程;2010年02期
2 张维润;樊雄;;集成膜工艺海水淡化与浓海水综合利用[J];水处理技术;2007年02期
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