界面聚合之奈米過濾膜的抗氯性研究; The chlorine-resistant properties of nanofiltration membranes by interfacial polymerization

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Title:	界面聚合之奈米過濾膜的抗氯性研究;The chlorine-resistant properties of nanofiltration membranes by interfacial polymerization
Authors:	邱政一;Cheng-yi Chiu
Contributors:	化學工程與材料工程研究所
Keywords:	奈米過濾膜;三聚氰氯;界面聚合法;抗氯性;cyanuric chloride;interfacial polymerization;chlorine-resistant;nanofiltration membrane
Date:	2009-07-02
Issue Date:	2009-09-21 12:31:21 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	目前市售的商業化奈米過濾膜大多為醯氯與對苯胺使用界面聚合方式製成之聚醯胺薄膜，其結構對水溶液中的活性氯非常敏感，為了探討與聚合單體對薄膜抗氯性之影響，本研究利用界面聚合的方式製作奈米過濾膜，在水相單體的部分，選用二乙基三胺(DETA)取代對苯胺，以測試苯環結構的存在與否對薄膜氯的容忍性之影響。油相單體則選用三聚氰氯(CC)與1,3,5 均三氯甲苯(TMC)做比較，以測試具不同結構與反應官能基的單體對薄膜氯的容忍性之影響。最後藉由CC與DETA此二結構不帶有苯環的單體，聚合出不具醯胺結構分離層，試圖製作出對氯具有抵抗能力的奈米過濾膜。研究結果發現，CC type 薄膜與TMC type 薄膜的水通透量分別為1.42 ± 0.27 (kg/m2 h atm)、2.06 ± 0.24 (kg/m2 h atm)，對MgSO4阻擋率分別為79.21 ± 3.93 (%)、87.01 ± 4.68 (%)。TMC type、CC type薄膜對四種鹽類阻擋順序皆為R(Na2SO4) > R(MgSO4) > R(MgCl2) > R(NaCl)，屬於負電性膜。經四級胺化後膜材的正電性提升，但其阻擋順序顯示薄膜仍為負電性薄膜。由曝氯時間達96小時，氯濃度為500 ppm的實驗結果可發現，CC type薄膜對氯的容忍度遠大於TMC type薄膜，可見當分離層結構不具有醯胺鍵結與苯環結構，其對氯的容忍性可大幅度提高。經四級胺化薄膜，薄膜對氯的容忍性下降，並不如預期的能提升抗氯性效果。與商業膜比較，由鹽類阻擋率的變化可以發現，CC type薄膜對氯的容忍度優於Filmtec所製作的NF-90，通流量變化較小也證明CC type薄膜結構較為穩定。另外以PVDF做為基材膜的實驗中，當丙烯酸接枝於薄膜表面時，其丙烯酸溶劑的選擇將對聚合結果造成重大的影響。使用水與異丙醇作為溶劑，由FTIR鑑定結果可以發現，以水作為溶劑所改質的PVDF膜，其丙烯酸特徵峰最為明顯，代表其接枝程度大於以異丙醇作為溶劑。但是經過使用CC與DETA行界面聚合10分鐘後，薄膜對MgSO4阻擋表現卻是以異丙醇當溶劑為最佳，阻擋率可達到85.07 ± 4.12 (%)。但隨著過濾次數增加，膜過濾表現會隨之下降，再現性差，因此並未做抗氯性測試。 Most commercial available nanofiltration membranes were composed by dichloride and phenyl diamine by using interfacial polymerization. However, Polyamides membranes show bad chlorine-tolerance. In order to evaluate the effect of the polymerization monomer for the chlorine tolerance of the membrane, the interfacial polymerization method was used to manufacture the thin-film-composite membrane. The phenyl diamine was replaced with diethylenetriamine to avoid the aromatic structure for increase the chlorine-tolerance property. Cyanuric chloride (CC) and Trimesoyl chloride (TMC) were used to The experiment results show that the water permeability of CC type and TMC type membrane was 1.42 ± 0.27 (kg/m2 h atm) and 2.06 ± 0.24 (kg/m2 h atm), respectively. The results also show that the rejective rate of these two types of membranes to MgSO4 were 79.21 ± 3.93 (%) and 87.01 ± 4.68 (%).We found that the order of rejective rate in these two membranes was the same, and the order was R (Na2SO4)> R (MgSO4)> R (MgCl2)> R (NaCl). This order of salt rejection shows that both the membrane were negatively charged . After improving the positive charge of the membranes by quaternization, we could find that both the membranes were still negatively charged by observing the order of salt rejection . According to the chlorine-tolerance study, the CC type membrane shows excellent chlorine-tolerance property than TMC type membrane after the membrane was exposure in aqueous sodium hypochlorite (500 ppm active Cl) for 96 hours. The results indicated that both the existence of polyamide structure and quartnizing the membranes would reduce the chlorine-tolerance property. In addition, comparing the two types of membranes with the commercial membranes, CC type membrane has better chlorine-tolerance than NF-90. In addition to PVDF membrane experiment, it is very important for the choice of solvent in polymerization condition. The FTIR spectrum was employed to characterize the nanofiltration layer, when use water and isopropanol (IPA) as the solvent. The result shows that, the acrylic acid grafting degree of the membrane by water was higher then the IPA one. But, the membrane which acrylic acid grafted by IPA has better sal rejection then water one. The salt rejection of MgSO4 was 85.07 ± 4.12 (%). The PVDF NF membranes were not tested for chlorine-tolerance propertys because the poor reproducibility of the membrane.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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