DEVELOPMENT OF LOW FOULING MEMBRANE USING POLYANILINE (PAN1)-POLYETHERSULFONE (PES) BLEND

NOR FAIZAH BINTI RAZALI

THESIS IS SUBMITTED IN FULFILMENT OF THE DEGREE OF DOCTOR OF PHILOSOPHY

FACULTY OF ENGINEERING AND BUILT ENVIRONMENT UNIVERSITI KEBANGSAAN MALAYSIA

BANG1

ABSTRACT

In this present study, polyethersulfone (PES) was modified by blending with polyaniline nanoparticles (PANI) via phase inversion to produce ultrafiltration (UF) membrane with an improvement in the hydrophilic property and the performance. Polyaniline nanoparticle was synthesized via chemical oxidation in aqueous hydrochloric solution. The polyaniline nanoparticles were characterized using scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X- ray diffi-action (XRD), Fourier transform infi-ared spectroscopy (FTIR) and Ultraviolet-visible spectroscopy (UV-Vis) analysis. The polyaniline particle size obtained was in the range of 22-50'nm and the crystalline nature of these nanoparticles was confirmed from the XRD patterns. The prepared membrane were then characterised by water permeability test, Scanning electron microscope (SEM), Atomic force microscopy (AFM), Contact angle, Zeta potential, X-ray photoelectron spectroscopy (XPS), Molecular weight cut-off (MWCO) and Tensile Strength. It was found that blended membranes have higher permeability than the controlled membrane. The decrease of static water contact angle from controlled to blended membranes (64.3" to 54.95') indicated that PANI nanoparticles has increased the surface hydrophilicity. The blended membrane showed an improvement in the membrane structure when observed by SEM. .The MWCO profiles of the prepared membranes are in the range of 22 to 35 kDa. Mechanical properties of the fabricated membranes shows that the addition of the PANI nanoparticles reduce the tensile strength of PES due to the semi-crystalline structure of PANI nanoparticles. AFM proved that the roughness of the membranes was increased with the addition of PANI nanoparticles but are significantly more hydrophilic. AFM also provide tool to calculate the membrane pore size distribution which are (1-6 nm) for controlled and (2-40 nm) for blended membranes. Central Composite Design (CCD) of the response - surface method (RSM) was used for the optimization of blended PESIPANI membranes. The optimal conditions were 18.33 wt% PES, 0.75 wt% PANI and 1.34 minutes of evaporation time with the predicted results of water permeability, salt rejection and contact angle as 62.2 L/YP~' h bar, 32.4% and 54.955 respectively. The fouling studies were conducted by tested the membranes with four different types of foulant, Bovine Serum Albumin (BSA), humic acid (HA), silica nanoparticles and E.coli and Bacillus bacteria. The fouling analysis demonstrated that the modified membranes show fewer tendencies for fouling. The modified membrane also showed high flux recovery ratio. In the rejection test, the blended membrane shows improvement in the BSA and humic acid rejection eventhough the pore size are higher than the controlled membrane. However, for silica nanoparticles, the rejection gives lower value due to the molecular shape and chemical property of silica nanoparticles. For the bacteria resistant test, the modified membrane shows less attack from the

. bacteria which shows improvement in the biofouling activity. Analysis of the flux data using Hermia model suggested that complete blocking model may be the dominant fouling mechanism for the controlled membrane, whereas intermediate blocking, complete blocking and cake formation may be the major fouling mechanism for the produced and commercial membrane. In this study, both of the modified membrane shows lot of improvement in antifouling properties compared to the controlled membranes. Therefore the blended membrane offers a strong potential for possible use as a new type of anti-fouling ultrafiltration membrane.

ABSTRAK

Penyelidikan ini adalah mengenai polietersulfon (PES) yang telah diubah strukturnya melalui pencampuran dengan Polianilin (PANI) nanopartikel melalui kaedah kesongsangan fasa. Kajian ini bertujuan untuk menghasilkan membran ultrapenurasan (UF) dengan penarnbahbaikan sifat hidrofilik serta memperbaiki sifat membran PES yang sedia ada. PANI dihasilkan melalui oksidasi kirnia dalam larutan berasid. PANI dianalisis menggunakan mikroskop elektron imbasan (SEM), transmisi elektron mikroskop (TEM), belauan sinar-X (XRD), Spektrometer infra-merah jelmaan Fourier (ATR-FTIR) d m ultralembayung spektroskopi (UV-Vis). Saiz PANI adalah dalam julat 20-50 nm dan bentuk hablur PANI disahkan melalui XRD. Membran yang dihasilkan diklasifikasikan oleh ujian kebolehtelapan, SEM, mikroskop daya atom (AFM), sudut sentuh, cas membran, spektrokopi fotoelektron sinar-X (XPS), nilai potongan berat molekul (MWCO) dan kekuatan regangan. Membran yang diubah suai (membran campuran) mempunyai kebolehtelapan yang tinggi berbanding membran PES (membran kawalan). Penurunan sudut sentuh daripada 64.3" ke 54.95" menunjukkan PANI meningkatkan sifat hidrofilik perrnukaan membran. Membran campuran juga menunjukkan penarnbahbaikan dalam struktur membran apabila diperhatikan melalui imej SEM. Melalui profil MWCO, membran yang telah dihasilkan mempunyai nilai potongan berat molekul di dalam julat 22-35 kDa. Walaubagaimanapun, sifat mekanikal membran campuran menunjukkan sedikit kerapuhan berikutan bentuk hablur PANI yang bersifat separa kristal. Ujian AFM pula menunjukkan peningkatan dalam sifat kekasaran membran tetapi dalam masa yang sama meningkatkan sifat hidrofiliknya. AFM juga boleh digunakan untuk mengira julat saiz liang membran iaitu (1-6 nm) bagi membran kawalan, dan (2-40 nm) untuk membran- campuran. Perisian Response Surface Method (RSM) melalui kaedah Central Composite Design (CCD) digunakan untuk menentukan nilai optimum komposisi membran cmpuran. Nilai optimum yang diperoleh adalah 1 8.33 wt% PES, 0.75 wt% PANI dan 1.34 minit untuk masa pemeluwapan. Nilai anggaran untuk kebolehtelapan air, penyahgaraman dan sudut sentuh adalah 62.2 ~ / m ~ h bar, 32.4 % dan 54.954 Ujian ketahanan kotoran dilakukan dengan menguji membran dengan empat jenis bahan punca kotoran iaitu Bovine Serum Albumin (BSA), Asid Hurnic (HA), Silika nanopartikel dan bakteria E.coli serta Bacillus. Ujian menunjukkan membran campuran mempunyai ketahanan yang tinggi terhadap kotoran berbanding membran kawalan. Membran campuran juga menunjukkan kebolehan untuk diguna semula yang tinggi. Dalam ujian penolakan, membran carnpuran menunjukkan penambahbaikan dalarn penolakan BSA dan asid humic walaupun saiz liangnya lebih besar dari membran kawalan. Namun begitu, ujian penolakan adalah rendah bagi silika nanopartikel kerana saiz dan sifat kimia yang terdapat dalam silika itu sendiri. Untuk ujian rintangan terhadap bakteria, membran campuran menunjukkan kurangnya serangan bakteria pada membran tersebut. Ini menunjukkan membran campuran mernpunyai sifat anti biokotoran yang tinggi. Model hermia meramalkan bahawa membran kawalan mengalami mekanisma tersumbat sepenuhnya, manakala membran campuran munglun mengalami tiga mekanisma kotoran iaitu tersumbat sederhana, tersumbat sepenuhnya dan terbentuknya kek. Dalam kajian ini, membran campuran menunjukkan sifat anti kotoran yang tinggi berbanding membran kawalan. Oleh itu, membrstn campuran ini mempunyai potensi yang tinggi untuk dikomersilkan sebagai membran ultrapenurasan yang mempunyai sifat anti kotoran yang tinggi.

REFERENCES

Abbasi, M. & Taheri, A. 2013. Effect of Coagulant Agents on Oily Wastewater Treatment Performance Using Mullite Ceramic MF Membranes: Experimental and Modeling Studies. Chinese Journal of Chemical Engineering, 21 : 125 1-1 259.

Abdolreza, M. & Azizollah, S. 1998. Application of conducting polyaniline membranes (11) separation of H2S04/H3P04 and HN03/H2S04 using dialysis, electrodialysis and electrodynamic Methods. Iranian Polymer Journal 98: 1026-1265.

Abe, M., Ohtani, A., Umemoto, Y., Akizuki., S., Ezoe, M., Higuchi, H., Nakarnoto, K., Okuno, A. and Noda, Y. 1989. Applications of Polyaniline Nanofibers and Nanocomposites. Journal of the Chemical Society, Chemical Communications 1 73 6- 1738.

Abelson, P. H. 1989. Synthetic membranes. Science 244: 1421

Adout, A., Kang, S., Satekin, A. A., Mayes, A., Elimelech, M. 2010. Ultrafiltration membranes incorporating amphiphilic comb copolymer additives prevent irreversible adhesion of bacteria. Environmental Science Technology 44: 2406-24 1 1 .

Afshad, T. 1994. Electronic properties of novel polypyrrole and polyaniline materials: a resistometric approach. Ph.D Thesis. University of Wollongong.

Ahrnad, A.L., Low, S .C., Abd, S. S. R., & Ismail, A. 2009. Optimization of membrane performance by thermal-mechanical stretching process using responses surface methodology (RSM). Separation Purification Technology 66: 177-1 86.

- Aimar, P. Meireles, M. & Sanchez, V. 1990. A contribution to the translation of retention

curves into pore size distribution for sieving membranes. Journal of Membrane Science 54: 321 - 338.

Aimar, P., Harmant, P. & Bacchin, P. 1996. Critical flux in ultrafiltration of colloid suspensions, in: Proc. IMSTEC'96, 12-1 4 November 1996, Sydney, Australia, Vol. 1, pp. 115-117.

Al-Amoudi, A. & Lovitt, R. W. 2007. Fouling strategies and the cleaning system of NF membranes and factors affecting cleaning efficiency. Journal of Membrane Science 303 14-28.

Alborzfar, M., Jonsson, G. & Gron, C. 1998. Removal of natural organic matter from two types of humic ground waters by nanofiltration. Water Resources 32(10): 2983-2994.

AlMalek, S. A., Abu Seman, M. N., Johnson, D. & Hilal, N. 2012. Formation and characterization of polyethersulfone membranes using different concentrations of polyvinlylpyrrolidone. Desali~tation 288: 3 1-39.

Amado, F. D. R., Rodrigues, M. A. S., Morisso, F. D. P., Bernardes, A. M., Ferreira, J. Z. & Ferreira, C. A. 2008. High-impact polystyrene/polyaniline membranes for acid