兩性離子表面改質對聚醯胺/聚醚碸超薄複合膜奈米過濾效能之影響

Effect of surface zwitterionization of polyamide/ polyethersulfone thin film composite membrane on nanofiltration performance

張嘉祐(JIA-YOU ZHANG)

指導教授 ： 蔡惠安 ； 李魁然

中原大學/工學院/化學工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201528

摘要

水資源短缺是當今人類最需要解決的問題，為了更有效的利用水資源，人們研究了很多方法，其中薄膜分離技術因為其節能高效的特性，引起學者們廣泛的探索。奈米過濾(nanofiltration)是薄膜分離技術的一種，其高滲透量及分離小分子的能力，使這項技術在近年來蓬勃發展。
本研究採用界面聚合法，在聚醚碸(polyethersulfone, PES)非對稱膜表面製備聚醯胺(polyamide, PA)選擇層，應用於奈米過濾操作程序，分離鹽類水溶液。在界面聚合過程，將四種共單體：N,N-二丁基乙二胺 (N,N-dibutylethylenediamine, DBEDA)、N,N-二乙基乙二胺(N,N-diethylethylenediamine, DEEDA)、N,N-二甲基-1,4-苯二胺 (N,N-dimethyl-1,4-phenylenediamine, DMPDA)和N,N-二甲基乙二胺(N,N-dimethylethylenediamine, DMEDA) 分別與哌嗪(piperazine, PIP) 混合，形成水相單體溶液，再與均苯三甲醯氯(trimesoyl chloride, TMC)有機相溶液，藉由界面聚合反應製備PA/PES薄層複合膜(thin-film composite membrane, TFC membrane)，探討不同水相共單體對TFC薄膜的結構型態、親疏水性、熱穩定性及奈米過濾效能之影響。研究發現，使用DEEDA作為水相共單體可以有效提升薄膜的奈米過濾效能，未添加水相共單體參與界面聚合反應之TFC薄膜，其純水通量為46.4 LMH；使用DEEDA作為水相共單體，DEEDA與PIP濃度各為0.35 wt%與0.45 wt% ，與TMC進行界面聚合反應時，TFC薄膜的純水通量提升至56.9 LMH，且保持二價鹽的阻鹽率，並降低一價鹽NaCl的阻鹽率。
為提升TFC薄膜之親水性質，進一步將TFC的PA選擇層與1,4-丁磺酸內酯(1,4-butane sultone, 1,4-BS)反應，促進PA選擇層上的季銨反應，完成膜表面的兩性離子改質。兩性離子改質後的薄膜，藉由元素鑑定證實薄膜成功接枝SO3-，並透過固體表面電位分析儀證實改質後的薄膜相較於未改質的薄膜帶更正電，且薄膜之奈米過濾效能及抗結垢性能也得到了提升，對Na2SO4與MgSO4的鹽水通量分別為59.6 LMH與62.3 LMH，鹽截留率分別保持在92.7 %及86 %。相比於未改質薄膜的91.3 %通量回復率，改質後的薄膜通量回復率上升至99 %，有效提升抗結垢性能。

關鍵字

兩性離子 ； 共單體 ； 界面聚合 ； 奈米過濾

並列摘要

The shortage of water resources is one of the key problems that the society is facing today. Scientists have explored different approaches to produce clean water. Among them is the membrane separation technology that caused massive attention due to its energy-saving and high-efficiency. Nanofiltration is a kind of membrane separation technology and it has high water permeability and the ability to separate small molecules have made this technology flourish in recent years.
In this study, the interfacial polymerization method was used to prepare a polyamide (PA) selective layer on the surface of a polyethersulfone (PES) asymmetric membrane, which was applied to the nanofiltration process to separate salt aqueous solutions. Four co-monomers: N,N-dibutylethylenediamine (DBEDA), N,N-diethylethylenediamine (DEEDA), N,N-dimethyl-1,4-phenylenediamine (DMPDA) and N,N-dimethylethylenediamine (DMEDA) was mixed with piperazine (PIP) to form an aqueous monomer solution, and then react with trimesoyl chloride (TMC) organic phase solution to prepare PA/PES thin- film composite membranes by interfacial polymerization. The effects of different aqueous co-monomers on the structure, hydrophilicity, thermal stability and nanofiltration performance of TFC membranes was studied. It was found out that the use of DEEDA as the water-phase co-monomer can effectively improve the nanofiltration performance of the membrane. Compared with the pristine membrane, using DEEDA as the co-monomer (with DEEDA and PIP concentration of 0.35 wt% and 0.45 wt%, respectively), the pure water flux of the TFC membrane was improved from 46.6 LMH to 56.9 LMH, while maintaining the divalent salt rejection and reducing the rejection of monovalent salt.
To further enhance the hydrophilicity of TFC membranes, the PA selective layer was further reacted with 1,4-butane sultone (1,4-BS) to promote the quaternary ammonium reaction on the PA selective layer and complete the zwitterion modification of the membrane surface. It was confirmed in the XPS analysis SO3- is present in the membrane surface, and it was confirmed through zeta potential test that the membrane was more positively charged than the unmodified one. The nanofiltration and antifouling performance of membranes was also improved. The salt fluxes for Na2SO4 and MgSO4 are 59.6 LMH and 62.3 LMH, respectively, and the salt rejection rates are maintained at 92.7 % and 86 %, respectively. The flux recovery ratio of the membrane increased to 99 %, compared to the 91.3 % flux recovery rate of the unmodified membrane, the anti-fouling performance is improved.

並列關鍵字

Co-monomers ； Interfacial polymerization ； Nanofiltration ； Zwitterion

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