Zawati Harun

Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

Abstract In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A) and 10–15 μm (denoted as type B), at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. The support was prepared using kaolin type A induced asymmetric structure by combining macroporous voids and sponge-like structure in the support with pore size of 0.38 μm and 1.05 μm, respectively, and exhibited ideal porosity (27.7%), great mechanical strength (98.9 MPa) and excellent gas permeation. Preliminary study shows that the kaolin ceramic support in this work is potential to gas separation application at lower cost.

Effects of water as non-solvent additive on performance of polysulfone ultrafiltration membrane

In this work, polysulfone ultrafiltration membranes were prepared via simple phase inversion with distilled water as non-solvent additive. The main reason for the addition of water in polysulfone dope solution preparation was to enhance the membranes structure. In the dope, 15 wt. % of polysulfone was used and water was varied up to 6 wt. %. The effects of water on morphology, porosity and tensile properties were investigated in detail. From the porosity test, results showed that the addition of water has improved membrane porosity up to 53 %. The FESEM images revealed that membrane morphology has also been modified. However, the tensile properties of membrane decreased as water content increased which may be due to the porosity interaction between polysulfone/NMP with water.

Effect of Thermodynamic Properties on Porosity of Ceramic Membrane Prepared by Phase Inversion

In this present work, the effects of phase inversion ceramic membranes prepared by phase inversion were investigated. Kaolin with 25µm was used as the composition of membrane preparation. The amounts of kaolin investigated were 60g, 70g and 80g respectively while the temperature was conducted assist room temperature and 3°C. Non-solvent additive with 6g distilled water present formation of pore during phase inversion.The effects of phase inversion temperature and kaolin composition on morphology and porosity were investigated in detail. Result of porosity showed that by decreasingphase inversion temperature improve the membrane porosity up to 64%. In addition, the FESEM images explained that membrane morphology obviously change with the effect of temperature during phase inversion process.

Performance Studies of Polysulfone-Based Membrane: Effect of Silica Morphology

In the present work, polysulfone (PSf) ultrafiltration membranes were prepared by solution casting. The effects of rice husk silica (RHS) on the surface properties of the PSf/Polyethylene glycol (PEG) membrane were observed and investigated. Characterizations were conducted to determine the membrane cross-section area and RHS distribution. The structure of RHS and morphology of membrane were analyzed by using X-ray diffractometer (XRD) and scanning electron microscope (SEM). XRD pattern showed that the amorphous silica was produced from rice husk ash (RHA). The analysis of SEM indicates that the addition of RHS obviously changed the microstructure of the membrane especially at top layer and sub layer.

The Effect of Amorphous Rice Husk Silica to the Polysulfone Membrane Separation Process

This study investigates the effect of additive rice husk silica and Polyethylene glycol (PEG) on the performance of polysulfone (PSf) membrane. The membrane was prepared by phase inversion method using PSf, N-methyl-2-pyrrolidone (NMP) and rice husk silica was added as an additive. The performance of the membrane was analyzed by using distilled water for permeation test and humic acid for the rejection test. The result showed that the hydrophilic of PSf/PEG membrane has significantly improved the permeation and rejection performance with addition of rice husk silica. The results showed that with addition of 3% rice husk silica give the highest rejection flux at 196.63 L/m2hr with the rejection value 98%.

Drying Comparison of Nonhygroscopic and Hygroscopic Materials

This paper investigates and presents the simulation of drying for hygroscopic and nonhygroscopic materials. This present work used a coupled mathematical model of mass, heat and gas transfer that implemented to finite element method in two dimensional and numerically compute using Skyline solver to capture highly nonlinear transient process. Bound water contribution was taken into account in the drying of hygroscopic materials by incorporating constitutive equation of bound water. The results showed drying process can be divided into three periods named constant rate period (CRP), first falling rate period (FRP1) and second falling rate period (FRP2). Capillary action is dominated during CRP before vapour diffusion takes place in FRP1. Bound water movement is generated by vapour pressure gradient exists that represent hygroscopic material.

Effect of Rice Husk on Fired Ceramic Shell Strength

In recent years, ceramic shell mould for investment casting process is often associated to defects due to its brittle properties. The defects would originate from cracking mechanism yielded from the ceramic brittleness. In this work, the improvement of ceramic shell mould by reinforcement technique was studied and analyzed. Rice husk consisting high percentage of silica content with the ability to withstand high temperature during casting process was studied as the reinforcing component as to impede cracking mechanism. Higher Modulus of Rupture (MOR) value of ceramic shell reinforced by rice husk fiber as compared to the non-reinforced ceramic shell MOR value was obtained. Nonetheless, presence of the fused silica phase from rice husk fiber was also found to lead the formation of a new phase of zircon (ZrSiO4). These two factors were found to influence the ceramic shell composition and indirectly enhanced the ceramic shell strength performance.

Effect of MgO Additive on Microstructure of Al2O3

In this work, the consolidation of different alumina particles via sintering process was conducted to the compacted alumina pellets. This consolidation was also assisted with the sintering aid, MgO to densify the final ceramic structure. Comparison between the influence of additive to the different particles size of compacted alumina by observing the microstructure and physical properties was conducted. The value physical properties and microstructure clearly show that for both particle size of alumina, MgO additive can increase the density value and improve microstructure properties.

Drying Simulation of Ceramic Shell Build Up Process

In this work, a two-dimensional numerical model for the convective drying process of ceramic shell layers was developed. The governing system of fully coupled non-linear partial differential equations describing the process was derived from a mechanistic approach along with the implementation of continuum model. The most extensive formulation of the material used in many hygrothermal and soil transport investigation was adopted as the basis for further development in this work. Two examples comprising one dimensional brick drying and shell drying are solved to validate and demonstrate robustness of the approach. Validation within a one dimensional framework showed that the model presented is in a good agreement with other studies that have been reported previously in the drying of porous material. A two layers case study which illustrate the drying of ceramic shell layers are compared and contrasted against experimental data on shell drying, showing good agreements.

Fabrication and characterization of affordable hydrophobic ceramic hollow fibre membrane for contacting processes

Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique, followed by a grafting with fluoroalkylsilane (FAS). The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes (gas permeation, mechanical strength, pore size, porosity, tortuosity, morphology, and contact angle) by the addition of alumina (Al2O3) to the pure kaolin with mono or multiparticle sizes. By varying the overall loading and particle size of alumina addition, different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange. The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140° after grafting. Kaolin–alumina-4, one of the hollow fibres fabricated in this work, achieved a mean pore size of 0.25 μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10-5 mol·m-2·Pa-1·s-1, which makes the hollow fibre most suitable for the membrane contactor application.