Abstract: The efforts and attempts made in the past decades have witnessed a considerable amount of research interest in potential of various inorganic nanomaterials for the development and innovative environmental applications. Inorganic nanofillers such as metal oxides nanoparticles, carbon nanotubes and silver nanoparticles are incorporated into polymeric membranes to render the desired properties, i.e high flux, high rejection and enhanced fouling resistance to suitably applied in liquid-based filtration for waste and wastewater applications. This brief review highlights the state-of-the-art overview in the recent progress and advancement made in the utilization of nanofiller/polymer nanocomposite to remediate the current bottlenecks and issues that stumble the further development of the conventionally used polymeric membranes.
Abstract: The fouling problem has to be solved because fouling significantly reduces the performance of porous polymeric membranes. This paper presents methods to prepare low fouling membranes or to modify commercial/existing membranes to be low fouling membranes. At first, the principle of membrane separation as well as fouling phenomenon is presented. Important low fouling characters are also outlined. Thereafter, modification of membrane polymers to obtain low fouling character, principle as well as recent development in preparation of low fouling polymeric membranes and membrane modification of commercial/existing membrane are discussed.
Abstract: Electrospinning offers the unique ability to produce fibers with very small diameters down to a few tens of nanometers and an attractive mechanical appearance as well as the controllability of morphology, surface and pores structure. However, the main drawback of the conventional electrospinning technique is its low productivity. In order to produce high yield nanofibers, the production rate of nanofibers must be improved. The multinozzle and drum collector electrospinning system was then developed to overcome the problem. The multinozzle sub-system was used to increase the production rate of nanofibers while the drum collector was utilized to maintain the uniformity and thickness of stacked nanofibers. A solution prepared by dissolving waste styrofoam in the mixture of tetrahydrofuran (THF), citronella oil and cajuput oil was the precursor to produce the stacked styrofoam nanofibers.
Abstract: Fluorinated tin oxide (FTO) is well known transparent conductive oxide which is widely applied for optoelectronic applications. Commercially, high-performance (FTO) film was fabricated by sputtering method or other low pressure methods. The product of these methods is expensive due to the high price of capital cost for the apparatus. To cut the price of FTO, atmospheric condition methods were developed and actively investigated using a simple device. By controlling the process conditions; such as processing temperature, precursor concentration, doping concentration, and reactor configuration; high performance FTO glass was successfully produced. The sheet resistance of the prepared FTO glass can be controlled from 9.55 – 63 Ω/□. In addition, its transparency is approximately 77 % which is ideal characteristics for the dye sensitized solar cell (DSSC) electrode application.
Abstract: A microcantilever has attracted interest in an application of high sensitivity sensor for chemical, physical, or biological objects. In this paper, we investigate a possibility of a piezoresistive microcantilever for gas sensing using a static and a dynamic modes operation. The gas used here is a liquefied petroleum gas (LPG). The measurement was performed by a Wheatstone bridge circuit in order to measure the microcantilever deflection or resonance frequency shift of the microcantilever vibration. The result shows that in the static mode, an output of Wheatstone bridge circuit, which attributes to the microcantilever deflection, changes due to the gas detection. For the dynamic mode, a voltage of peak-to-peak, which represents the microcantilever vibrations, decreases with increasing the gas flow time. This occurs due to the resonance frequency shift caused by the addition of gas molecules on the microcantilever surface. These results indicate that the developed system can be used as the gas sensor.
Abstract: The effect of needle size on the fiber length was studied and investigated. A polymer solution of cellulose acetate (CA) and organic solvent was ejected from various sizes of needle gauge then the electrospun polymer fibers were adhered on a collector plate. The diameter of fibers was ranging from 80 to 570 nm and the length could be controlled from 10 to 240 µm by increasing the needle size. The breakaway to shortened nanofibers occurred due to the imbalance of force from the surface tension of the polymer solution and the longitudinal force of the applied voltage.
Abstract: This paper reports the effect of constant heating and progressive on carbon dioxide permeation characteristics in asymmetric hollow fiber polysulfone membranes. Glassy polymers are easily plasticized with the presence of plasticizing agents such as carbon dioxide. Constant heating were applied to the membranes to suppress CO2 induced plasticization. Membranes treated with constant temperature heating exhibits lower pressure-normalize flux for both carbon dioxide and methane compared to untreated membranes. This was probably due to densification of membrane skin layer during heating process. Denser skin layer increases the resistance in the membrane which resulted in decreased of pressure-normalize flux. A higher density of membrane skin layer was achieved by progressive temperature heat treatment. This further increased the resistance in the membrane resulted in a lower value of pressure normalized-flux. With the application of different feed pressure, an almost linear value of CO2 pressure-normalize flux shows that plasticization is successfully suppressed by heat treatment. From the results provided in this study, it can be concluded that plasticization of polysulfone hollow fiber membrane is successfully suppressed by heat treatment process.
Abstract: Poly (vinyl alcohol) (PVA)/chitosan nanofibers membranes were successfully prepared by electrospinning employing a multi-nozzle and a drum collector. The use of multi-nozzle and drum collector system is intended to produce stacked nanofibers to form a membrane as a matrix for burn wound healing application. The membranes thickness was controlled by varying applied voltage, flow rate, drum collector rotating speed, and nozzle-collector distance. The electrospinning process and nanofibers formation on the collector was observed using a digital camera. The scaling relationship between current-flow rate and current-voltage for PVA/chitosan fulfills power laws of I ~ Qα and I ~ Eβ, respectively.
Abstract: A simple way of producing nanoTiO2 on fiber polyvinyl alcohol (PVA) has been done using solution anatase TiO2 micro powder as a solution for electro spinner machine. The process relies upon the mixing of TiO2 and PVA in deionized water before converted it into fiber. The result shows that before and after heat treatment at 300°C, the electrospinning process are able to carry 60% TiO2 in the anatase phase and to reduce the fiber size and carry the crystalline in nanosize showing a potential way of making fiber carrying nanocrystalline anatase.