交聯幾丁聚醣薄膜在奈米過濾的應用

The applications of crosslinked chitosan membrane for nanofiltration

陳信吉(HSin- Chi Chen)

指導教授 ： 莊清榮 ； 阮若屈

中原大學/工學院/化學工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500301

摘要

摘要

本研究是使用PAN(polyacrylonitrile)/PET當作奈米過濾薄膜(nanofiltration membrane，NF)的支撐層，並使用幾丁聚醣(Chitosan)和交聯劑3-環氧丙三甲基矽氧烷(3-glycidoxypropyl- trimethoxysilane，簡稱GPTMS)來製備成薄膜的選擇層。藉表面塗佈法(surface coating)製作成奈米過濾複合薄膜，並針對不同分子量的PEG以及MgSO4進行過濾測試，還有對複合薄膜進行一些物性以及化性的分析。
實驗首先對薄膜進行4大氣壓、8小時下，最高交聯劑含量(70wt%)的NF膜之透過量穩定狀態測試，對PEG8000約需要3.5小時，薄膜達穩定；MgSO4則需要2小時即達穩定。經由薄膜膨潤度的實驗測試發現，交聯劑GPTMS的添加能抑制幾丁聚醣在水溶液中被膨潤。藉由膜電性的測試發現，帶有正電荷的幾丁聚醣會隨著交聯劑GPTMS的添加量增加而漸漸降低正電量。幾丁聚醣/PAN經由NaOH以及HCl的後處理會使得薄膜變為更強的負電，且交聯劑增加負電性增強。經由強鹼以及強酸處理過的PAN，會使塗佈在其上的幾丁聚醣降低正電性甚至變為負電性的薄膜。從SEM發現幾丁聚醣薄膜的結構相當緻密，且隨著交聯劑添加至50wt%而使薄膜厚度減為最低，但當添加70wt%時厚度又增加。原子力顯微鏡的觀察發現，薄膜表面粗糙度會隨著交聯劑GPTMS的添加量增加而減低，添加至50wt%時薄膜表面粗糙度最低，添加至70wt%時表面粗糙度增加。NaOH的後處理對表面粗糙度影響不大，HCl的後處理則提高薄膜表面粗糙度。薄膜分離效能的結果發現測試進料PEG8000、MgSO4，PAN前處理對薄膜分離並無影響。進料溶液PEG8000、PEG200、MgSO4，膜透過量隨著pH值上升而上升，且隨著交聯劑含量增加而減少。進料溶液用不同分子量PEG8000、PEG1000、PEG200水溶液，薄膜的分子量去除大小(MWCO)約在8000Da。利用NaOH、HCl進行薄膜後處理，鹼處理以及酸處理可以提高薄膜透過量，對阻鹽率則沒影響。總結其上結果得知表面塗佈法所得效能，PEG8000最佳的透過量以及阻擋率分別為0.5( kg/m2hr atm)、95%；MgSO4較佳的透過量以及阻擋率分別為0.55(kg/m2hr atm)、45%。

關鍵字

幾丁聚醣薄膜 奈米過濾

並列摘要

Abstract

In the study, we use PAN (polyacrylonitrile ) / PET as the support layer and 3-glycidoxypropyl-trimethoxysilane (GPTMS)as the crosslinker of chitosan. Chitosan and GPTMS preceed crosslinkimg reaction and be the top-layer of the composite nanofiltration membrane. We preceed some physical and chemical analysis for the membrane and test the performance by different molecular weight PEG and some kinds of salts.
The membrane with 70wt% GPTMS was operated at 4 atm and 8hour for PEG8000and MgSO4, we find the membrane reach steady state with PEG8000 solution for 3.5hr and MgSO4 PEG8000 solution for 3.5hr. By means of the swelling test, we find that the crosslinker would restrain the swelling of chitosan. By means of the measurement of the membrane electricity, we can get some result that crosslinker would reduce the positive charge of chitosan. When we treat the composite memebrane with NaOH and HCl, the membrane electricity would become more negative. If we increase the GPTMS content, the membrane would be more negative. On the other hand, the pretreatment of PAN by NaOH and HCl would make the chitosan/GPTMS membrane become negative electricity.
From the SEM image ,we can find the structure of chitosan is very dense and by means of increasing the GPTMS to 50wt% , the thickness would reduce and the thickness increase when the GPTMS content add to 70wt%. From the AFM experiment , the roughness would reduce by adding GPTMS to 50wt% , but the roughness increase at 70wt% GPTMS. Besides, the treatment by NaOH will affect the roughness more less, but the treatment by HCl would greatly increase the roughness. About the surface coating membrane, PAN pretreatment didn’t improve the performance of CS/PAN composite membrane. The feed solution PEG8000、PEG200、MgSO4 at different pH value, higher pH value, higher flux; higher crosslinker content ,less flux .
When feed solution with different molecular weight PEG, PEG8000、PEG1000、PEG200,we find the MWCO is 8000Da.Using NaOH and HCl as after-treatment agent , we find after-treatment would improve the flux and rejection of the membrane. The membrane provide more excellent performance with 2000ppm MgSO4 than with 1000ppm and 500ppm.The better performance of surface coating NF membrane，the flux and rejection of PEG8000 are 0.5(Kg/m2hr atm)、95%；the flux and rejection of MgSO4 are 0.55(Kg/m2hr atm)、45%.

並列關鍵字

chitosan nanofiltration membrane

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