Membran telah diiktiraf sebagai teknologi yang kos efektif untuk merawat air sisa berminyak. Walau bagaimanapun, membran polimer konvensional mempunyai kecenderungan untuk dikotor apabila merawat air sisa berminyak. Dalam kajian ini, membran polyvinylidene fluorida (PVDF)-poly(N-isopropylacrylamide) (PNIPAAm) telah disediakan untuk mengkaji penjerapan dan pelepasan minyak. Sifat-sifat membran dinilai menggunakan mikroskop elektron imbasan (SEM), spektroskopi inframerah ubah fourier (FTIR) dan geniometer. Pencirian menunjukkan membran yang diubah suai mempunyai ciri hidrofilik yang ditingkatkan pada suhu bilik. Nanopartikel juga didapati tersebar dalam PVDF dan kekasaran permukaan yang lebih tinggi telah dilaporkan. Ia adalah diperhatikan bahawa pada kepekatan rendah, ciri hidrofilik membran menyumbang untuk mencegah minyak untuk deposit pada membran. Walau bagaimanapun, kenaikan konsentrasi minyak menggalakan penjerapan akibat kecerunan konsentrasi. Selain itu, kekuatan ionik larutan boleh menimbulkan kesan saringan caj dan dengan itu meningkatkan pelekatan minyak pada membran. Walaupun terdapat peningkatan penjerapan minyak dalam persekitaran masin, ciri hidrofilik membran PNIPAAm-PVDF menghalang pemendapan minyak pada suhu di bawah LCST PNIPAAm. Pada suhu melebihi LCST, membran PNIPAAm-PVDF menunjukkan penjerapan yang lebih tinggi berbanding membran PVDF tulen. Ia adalah jelas terbukti bahawa dengan kitaran haba berulang, pembengkakan dan pengecutan nanopartikel PNIPAAm meningkatkan pelepasan minyak dari membran. Membran termos responsif ini telah memberi penerangan mengenai kemungkinan pembersihan membran tanpa kimia.
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Membrane filtration has been recognized as a cost-effective technology for treating oily wastewater. However, conventional polymeric membranes have high membrane fouling tendency when treating oily wastewater. In this study, a thermoresponsive PNIPAAm-PVDF nanocomposite membrane was developed to study the adsorption and desorption of oil water. The membrane structures were systematically characterized with geniometer, FTIR, SEM and AFM. The characterization showed the modified membrane with improved hydrophilicity at room temperature, has well dispersed nanoparticles within the PVDF and a higher surface roughness. It was observed that at low oil concentration, the hydrophilic composite membrane did contribute to prevent oil deposit on the membrane. However, as the concentration of oil increases, the concentration gradient dominates the adsorption process. It was also validated that the increase of salinity promotes adsorption of oil on both membranes. The ionic strength of the solution posed charge screening effect and hence increased the foulants adhesion on the membranes. Despite the increase in salinity, hydrophilicity of PNIPAAm-PVDF membrane inhibited the deposition of oil at temperature below the LCST of PNIPAAm. At temperature above LCST, PNIPAAm-PVDF membrane showed more significant adsorption of oil. It was clearly evident that with repeated thermal cycle, the swelling and de-swelling of the PNIPAAm nanoparticles could enhance the oil desorption from the membrane. This thermo-responsive membrane has shed light on the possibility of membrane cleaning without chemical.
Adsorption-desorption study of oil emulsion towrads PNIPAAM-PVDF nanocomposite membrane- salinity and temperature effect / Wong Hui Yin