抗污染性正渗透膜的研制及其在海水淡化中的应用

发布时间：2018-06-29 05:02

本文选题：正渗透膜 + 亲水性　；参考：《济南大学》2014年硕士论文

【摘要】：醋酸纤维素（CA）是一种非常易得的人造纤维，并且它还是一种成本低，，耐高温、化学性质稳定、机械性能强的膜材料，但由于该材料易降解，抗污染性较差，阻碍了其在海水淡化的进一步应用。本论文选用了醋酸纤维素为膜材料制备了正渗透膜，并以氧化石墨烯、纳米二氧化钛作为改性剂，采用共混改性的方法对正渗透膜进行改性，考察了正渗透膜的纯水通量、表面接触角以及膜的表面和断面结构，并对制备的正渗透膜进行了海水淡化测试。本论文首先考察了CA含量、溶剂比例、添加剂含量、支撑层的目数以及凝固浴温度对正渗透膜的纯水通量和反向盐通量的影响，确定了醋酸纤维素正渗透膜的最佳工艺参数：醋酸纤维素的质量分数为16%，DMF与丙酮的体积比为1:0.6，添加剂PEG400的质量分数为4%，在120目的聚酯筛网上刮膜，凝固浴温度为60℃。利用1M NaCl作为驱动液，去离子水作为原料液，在1h的测试时间里，所制备的醋酸纤维素正渗透膜的纯水通量为15L/m2·h以上，反向盐通量控制在在7.5g/m2·h以下。在最佳制膜工艺的基础上，加入了制备的氧化石墨烯，考察了氧化石墨烯的含量、共混温度对膜性能的影响。得到以下结论：氧化石墨烯（GO）的质量分数为0.15%，共混温度为50℃时，所制备的氧化石墨烯/醋酸纤维素共混正渗透膜的性能最佳。利用1MNaCl作为驱动液，去离子水作为原料液，在1h的测试时间里，所制备的膜的纯水通量达到16L/m2·h以上，反向盐通量控制在7g/m2·h以下。合成了混晶型的纳米二氧化钛，考察了纳米二氧化钛的含量、共混温度对改性膜性能的影响。得到以下结论：纳米二氧化钛（TiO2）的质量分数为1.25%，共混温度为60℃时，所制备的纳米二氧化钛/醋酸纤维素共混正渗透膜的性能最佳。利用1M NaCl作为驱动液，去离子水作为原料液，在1h的测试时间里，所制备的膜的纯水通量达到10L/m2·h以上，反向盐通量控制在5g/m2·h以下。利用接触角测试仪对所制备的正渗透膜进行耐污染性测试：醋酸纤维素正渗透膜的接触角为71.6°，具有一定的亲水性；氧化石墨烯/醋酸纤维素共混正渗透膜的接触角为58.2°，亲水性优于醋酸纤维素正渗透膜；纳米二氧化钛/醋酸纤维素共混正渗透膜的接触角为54.2°，在所制备的三种正渗透膜中亲水性最好。可以看出添加了改性剂后，增强了正渗透膜的亲水性。在改性过程中，纳米二氧化钛的亲水性好于氧化石墨烯。最后对所制备的正渗透膜进行模拟海水淡化测试，得到以下结论：利用2M葡萄糖作为驱动液，渤海海水作为原料液，在1h的测试时间里，醋酸纤维素正渗透膜的纯水通量整体变化不大，基本稳定在20L/m2·h；氧化石墨烯/醋酸纤维素共混正渗透膜的纯水通量一开始比较大，大约在30L/m2·h左右，但随着时间持续下降，最后阶段基本与改性前膜的纯水通量持平；纳米二氧化钛/醋酸纤维素共混正渗透膜的纯水通量整体比较稳定，基本稳定在25L/m2·h左右。
[Abstract]:Cellulose acetate (CA) is a very easy synthetic fiber, and it is a membrane material with low cost, high temperature resistance, stable chemical properties and strong mechanical properties. However, because of its easy degradation and poor anti pollution, it hinders its further application in seawater desalination. This paper has selected cellulose acetate as a membrane material to prepare positive infiltration. The permeable membrane was permeable with graphene oxide and nano titanium dioxide as modifier. The positive permeable membrane was modified by blending modification method. The pure water flux, surface contact angle and surface and section structure of the membrane were investigated, and the sea water desalination test was carried out for the prepared permeable membrane.
In this paper, the effects of the content of CA, the proportion of solvent, the content of the additive, the number of the support layer and the temperature of the support layer on the pure water flux and the reverse salt flux of the positive permeable membrane were investigated. The optimum process parameters of the cellulose acetate membrane were determined: the mass fraction of cellulose acetate was 16%, the volume ratio of DMF to acetone was 1:0.6, and the additive P The mass fraction of EG400 was 4%. The temperature of the coagulation bath was 60 C on the 120 polyester screen, and the solidification bath temperature was 60. 1M NaCl was used as the driving liquid and the deionized water was used as the raw material. In the testing time of 1H, the pure water flux of the prepared cellulose acetate permeation membrane was above 15L/m2. H, and the reverse salt flux was controlled below 7.5g/m2 H.
On the basis of the best film making process, the prepared graphene oxide was added, and the influence of the content of graphene oxide and the blending temperature on the performance of the film was investigated. The following conclusion was drawn: the properties of the prepared oxygen fossil / cellulose acetate / cellulose acetate blend membrane were the best when the mass fraction of GO was 0.15% and the blending temperature was 50. 1MNaCl is used as the driving fluid and deionized water is used as the raw material. In the testing time of 1H, the pure water flux of the prepared membrane is above 16L/m2. H, and the reverse salt flux is controlled below 7g/m2. H.
The mixed crystalline nano titanium dioxide was synthesized. The influence of the content of nano titanium dioxide and the blending temperature on the properties of the modified membrane was investigated. The following conclusions were obtained: the nano TiO 2 (TiO2) was 1.25% and the blending temperature was 60. The nano titanium dioxide / cellulose acetate blend membrane was the best. The use of 1M NaCl is used as the driving fluid and deionized water is used as the raw material. In the testing time of 1H, the pure water flux of the prepared membrane is above 10L/m2. H, and the reverse salt flux is controlled below 5g/m2. H.
The contact angle of the contact angle tester is used to test the resistance of the prepared permeable membrane: the contact angle of the acetate cellulose positive osmosis membrane is 71.6 degrees, and it has a certain hydrophilic property. The contact angle of the blend membrane of graphene oxide / cellulose acetate is 58.2 degrees, the hydrophilicity is superior to the fibrinosine acetate membrane, and the nanometer titanium dioxide / acetate fiber. The contact angle of the VD blend membrane is 54.2 degrees, and the hydrophilicity of the three kinds of positive permeable membranes is the best. It can be seen that the hydrophilicity of the positive permeable membrane is enhanced after the addition of the modifier.
Finally, the simulated seawater desalination test was carried out. The following conclusion was obtained: using 2M glucose as the driving fluid and Bohai sea water as the raw material, the pure water flux of the cellulose acetate positive permeable membrane changed little in the testing time of 1H, which was basically stable at 20L/m2. H, and the blending of graphene oxide / cellulose acetate was positive. The pure water flux of the permeable membrane is relatively large at the beginning, about 30L/m2 H. But with the continuous decline of time, the final phase is basically the same as the pure water flux in the modified membrane; the pure water flux of the nano titanium dioxide / cellulose acetate blend membrane is stable and stable at about 25L/m2. H.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P747

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