Synthesis and Characterization of Nanocomposite Hydroxy-Sodalite/Ceramic Membrane via Pore-Plugging Hydrothermal Synthesis Technique
Pages 1-7
M.O. Daramola, A. Dinat and S. Hasrod

DOI: http://dx.doi.org/10.6000/1929-6037.2015.04.01.1

Published: 13 March 2015

Abstract: In this article, synthesis and characterization of nanocomposite hydroxy sodalite (H-SOD)/α-alumina membrane via the so-called “pore-plugging” hydrothermal synthesis (PPH) protocol is reported for the first time. In nanocomposite architecture membranes, zeolite crystals are embedded within the pores of the supports instead of forming thin-film layers of the zeolite crystals on the surface of the supports. The as-prepared membranes were characterized with SEM and FTIR for morphology and purity of the H-SOD crystals. Compared to the conventional in-situ direct hydrothermal synthesis, membranes obtained from PPH possess higher mechanical and thermal stability. In addition, defect control with nanocomposite architecture membrane is possible because the zeolite crystals are embedded within the support pores of the membrane, thereby limiting the maximum defect size to the pore sizes of support. The nanocomposite architecture nature of the membranes safeguards the membrane from shocks or abrasion that could promote defects/inter-crystalline pores formation. These advantages could be helpful in the scale-up process of the preparation procedure of membranes at the commercial level with less-demanding conditions.

A Novel Approach to Synthesize Helix Wave Hollow Fiber Membranes for Separation Applications
Pages 8-14
Sung Ryul Park, Jeong-Hoon Kim, Aamer Ali, Francesca Macedonio and Enrico Drioli

DOI: http://dx.doi.org/10.6000/1929-6037.2015.04.01.2

Published: 13 March 2015

Abstract: Helix wave hollow fiber membranes are promising candidate to mitigate fouling and polarization effects in membrane operations. Current study describes a novel but simple approach to synthesize hollow fiber membranes with helix wave configuration. Poly(ether sulfone) (PES) based helix-waved hollow fiber membranes have been fabricated by dry-wet phase inversion process by using asymmetric coagulation conditions. Frequencies of the wave cycle have been observed approximately 20 and the wave length 7.1-7.6mm under the specifically required operating conditions defined by dope solution extrudate rate of 1g/min through 4cm of air-gap heights with 8.6m/min of winding speeds. On the other hand, simple hollow fibers are formed when the elongation force exerted by the winder is much higher than the surface tension of the external coagulant. The process can be useful for making polymer fibers for other applications as well.

Control of Membrane Surface Roughness and Pattern Wave Length by Changing the Nonsolvent (Water) Influx Rate
Pages 15-24
K.C. Khulbe, C.Y. Feng, T. Matsuura, W.J. Lau, E. Halakoo, R. Jamshidi Gohari and A.F. Ismail

DOI: http://dx.doi.org/10.6000/1929-6037.2015.04.01.3

Published: 13 March 2015

Abstract: The control of surface roughness of polyvinylidene fluoride (PVDF), polyethersulfone (PES), polysulfone (PS) and cellulose (CE) membranes was attempted by changing the rate of nonsolvent influx in the phase inversion process. PVDF and CE were chosen to represent membranes of high hydrophobicity and hydrophilicity, respectively, while PES and PS were chosen to represent membranes of intermediate hydrophobicity/-philicity. The concentration of sodium chloride (NaCl) in the aqueous coagulation medium was increased from 0 to 1.9 mol/L to decrease the rate of nonsolvent (water) influx in the solvent/nonsolvent exchange process. As well, the effect of polymer concentration and solvent on the surface roughness was investigated with respect to PVDF and PES. It was observed that the membrane surface roughness increased and decreased, respectively, for the hydrophobic PVDF and hydrophilic CE membrane as the rate of nonsolvent influx was decreased. For the PES and PS membranes of intermediate hydrophilic/-philicity, no significant roughness change was observed. The surface roughness tended to increase as the solution viscosity decreased. It was also observed that the pattern wave length of the hydrophobic membrane did not change significantly while that of the hydrophilic membrane increased significantly as the solvent influx rate was reduced. This trend is predictable by considering the shrinking or swelling of the cast polymer solution during the solvent/nonsolvent exchange process.

Scrutinizing the Nanostructural and Nanomechanical Features of Regenerated Cellulose Ultrafiltration Membranes
Pages 25-31
Luciano Paulino Silva

DOI: http://dx.doi.org/10.6000/1929-6037.2015.04.01.4

Published: 13 March 2015

Abstract: Ultrafiltration (UF) membranes have been widely used for many separation processes in which high performance is required. Commercial regenerated cellulose UF membranes with variable molecular weight cut-offs were characterized by high performance atomic force microscopy (AFM) using the novel quantitative nanomechanical mapping mode and the versatility of its signal channels towards nanoscale features elucidation of the materials surface. In addition, Raman spectroscopy was applied in order to investigate some possible chemical behavior changes associated with the UF membranes’ cut-offs. Overall, the results showed that the proposed AFM method was reliable to gain qualitative and quantitative data at unprecedented nanoscale resolution and such information can be used to distinguish UF membranes according to their specific molecular weight cut-offs and properties even on situations in which the molecular behavior were not influenced by the UF membrane’ cut-off. This approach can be useful on quality control procedures of researchers and manufacturers producing or modifying these polymeric materials.

Polychloroprene Rubber/Reduced Graphene Oxide (RGO) Nanomembranes for Pervaporation Separation of Azeotropic Mixtures
Pages 178-184
Maya M.G, Soney C. George, Thomasukutty Jose and Sabu Thomas

DOI: http://dx.doi.org/10.6000/1929-6037.2014.03.04.1

Published: 03 December 2014

Abstract: Chloroprene rubber is a high performance elastomer with remarkable ageing, heat and oil resistance. A new class of elastomeric nanocomposite was prepared by incorporating reduced graphene oxide (RGO) into chloroprene rubber (CR). RGO is synthesised from natural graphite, through GO route via Hummer’s method. This paper focuses on the influence of reduced graphene oxide on chloroprene rubber based elastomeric composites and their pervaporation separation of azeotropic liquid mixtures. The effect of concentration of RGO on separation factor, pervaporation separation index (PSI) and flux of the membranes were analysed. Chloroprene loaded with 0.9 phr (parts per hundred rubber) RGO shows an improved permeation rate among all other membranes while chloroform/acetone (80/20) azeotropic liquid mixture was used as feed solution. Flux increases with increasing the concentration of filler, reaches an optimum value and then decreases. Interestingly PSI also shows similar trend.