Synthesis of nanostructured titanium dioxide layer onto kaolin hollow fibre membrane via hydrothermal method for decolourisation of reactive black 5.

Hydrothermal method has been proven to be an effective method to synthesise the nanostructured titanium dioxide (TiO2) with good morphology and uniform distribution at low temperature. Despite of employing a well-known and commonly used glass substrate as the support to hydrothermally synthesise the nanostructured TiO2, this study emphasised on the application of kaolin hollow fibre membrane as the support for the fabrication of kaolin/TiO2 nanorods (TNR) membrane. By varying the hydrothermal reaction times (2 h, 6 h, and 10 h), the different morphology, distribution, and properties of TiO2 nanorods on kaolin support were observed by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). It was found that the well-dispersed of TiO2 nanorods have improved the surface affinity of kaolin/TNR membrane towards water, allowing kaolin/TNR membrane prepared from 10 h of hydrothermal reaction to exhibit the highest water permeation of 165 L/h.m2.bar. In addition, this prepared membrane also showed the highest photocatalytic activity of 80.3% in the decolourisation of reactive black 5 (RB5) under UV irradiation. On top of that, the kaolin/TNR membrane prepared from 10 h of hydrothermal reaction also exhibited a good resistance towards photocorrosion, enabling the reuse of this membrane for three consecutive cycles of photocatalytic degradation of RB5 without showing significant reduction in photocatalytic efficiency towards the decolourisation of RB5.

Investigation on the effect of sintering temperature on kaolin hollow fibre membrane for dye filtration.

Despite its extraordinary price, ceramic membrane can still be able to surpass polymeric membrane in the applications that require high temperature and pressure conditions, as well as harsh chemical environment. In order to alleviate the high cost of ceramic material that still becomes one of the major factors that contributes to the high production cost of ceramic membrane, various attempts have been made to use low cost ceramic materials as alternatives to well-known expensive ceramic materials such as alumina, silica, and zirconia in the fabrication of ceramic membrane. Thus, local Malaysian kaolin has been chosen as the ceramic material in this study for the preparation of kaolin hollow fibre membrane since it is inexpensive and naturally abundant in Malaysia. Due to the fact that the sintering process plays a prominent role in obtaining the desired morphology, properties, and performances of prepared ceramic membrane, the aim of this work was to study the effect of different sintering temperatures applied (ranging from 1200 to 1500 °C) in the preparation of kaolin hollow fibre membrane via dry/wet phase inversion-based spinning technique and sintering process. The morphology and properties of membrane were then characterised by SEM, AFM, FTIR, XRD, and three-point bending test, while the performances of membrane were investigated by conducting water permeation and Reactive Black 5 (RB5) dye rejection tests. From the experimental results obtained, the sintering temperature of 1400 °C could be selected as the optimum sintering temperature in preparing the kaolin hollow fibre membrane with the dense sponge-like structure of separation layer that resulted in the good mechanical strength of 70 MPa with the appreciable water permeation of 75 L/h m2 bar and RB5 rejection of 68%.