Malaysian Journal of Analytical Sciences Vol 21 No 2 (2017): 372 - 380

DOI: https://doi.org/10.17576/mjas-2017-2102-12

Surface modification of PSF/TiO₂membranes using silane coupling agents and DC plasma technique

(Modifikasi Permukaan Membran PSF/TiO₂ Menggunakan Ejen Gandingan Silana dan Teknik Plasma DC)

Soraya Ruangdit¹, Thawat Chittrakarn¹*, Sudkhet Anuchit¹, Yutthana Tirawanichakul¹, Chalad Yuenyao²

¹Membrane Science and Technology Research Center, Department of Physics, Faculty of Science,

Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand

²Department of Physics, Faculty of Science and Technology,

Phetchabun Rajabhat University, 83 M.11 St.Saraburi-Lom Sak, Muang, Phetchabun 67000, Thailand

*Corresponding author: tawat.c@psu.ac.th

Received: 26 August 2016; Accepted: 8 January 2017

Abstract

Preparation and surface modification of PSF/TiO₂ membranes by DC Ar-plasma were conducted to improve membrane hydrophilicity and gas permeation efficiency. Using TiO₂ as a photocatalyst, photocatalysis could be induced upon the plasma exposure. Radicals from this process led to an increase in the membrane hydrophilicity. In order to improve the dispersion quality of TiO₂ in an organic membrane, methyltrimethoxysilane (TMMS) or ethyltrimethoxysilane (TEMS) was utilized as coupling agents to modify the TiO₂ surface prior to blending. The coupling agents caused organic silane bonds on the TiO₂surface leading to a better dispersion of nanoparticle on the membrane matrix. The incorporation of modified-TiO₂ tended to decrease membrane water contact angles (WCA) to the lowest value when compared with PSF membranes with unmodified TiO₂ and neat PSF membranes. Results also showed that TMMS could produce better outcomes compared to TEMS. It was found that the modified-TiO₂ could decrease the WCA. More importantly, pressure normalized flux of CO₂ and CH₄ gases of PSF/modified-TiO₂ membrane was found to increase with slightly decrease in the selectivity of CO₂/CH₄.

Keywords: silane coupling agent, surface modification, gas separation membrane, low pressure DC-plasma, polysulfone

Abstrak

Penyediaan dan modifikasi permukaan membran PSF/TiO₂ oleh DC Ar-plasma telah dijalankan untuk meningkatkan kehidrofilikan membran dan kecekapan penyerapan gas. Menggunakan TiO₂ sebagai foto-pemangkin, fotopemangkinan dapat didorong apabila terdedah kepada plasma. Radikal daripada proses ini membawa kepada peningkatan dalam kehidrofilikan membran. Untuk meningkatkan kualiti penyebaran TiO₂ dalam membran organik, metiltrimetoksisilana (TMMS) atau etiltrimetoksisilana (TEMS) telah digunakan sebagai agen gandingan untuk mengubah suai permukaan TiO₂ sebelum campuran. Ejen-ejen gandingan menyebabkan ikatan silana organik di permukaan TiO₂ yang membawa kepada penyebaran nanopartikel yang lebih baik pada matriks membran. Penggabungan TiO₂ yang diubahsuai cenderung untuk mengurangkan sudut sentuhan air membran (WCA) kepada nilai yang paling rendah berbanding membran PSF dengan TiO₂ yang tidak diubahsuai dan membran PSF kawalan. Keputusan juga menunjukkan bahawa TMMS boleh menghasilkan hasil yang lebih baik berbanding PPSMI. Ia telah mendapati bahawa TiO₂ yang diubahsuai boleh mengurangkan WCA. Lebih penting lagi, tekanan fluks normal gas CO₂ dan CH₄ daripada membran PSF/TiO₂ yang diubahsuai didapati meningkat dengan sedikit penurunan kepilihan CO₂/CH₄.

Kata kunci: ejen gandingan silana, modifikasi permukaan, membran pemisahan gas, tekanan rendah dc-plasma, polisulfon

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