Manop Panapoy

Biodiesel production from waste cooking palm oil using calcium oxide supported on activated carbon as catalyst in a fixed bed reactor

A reactor has been developed to produce high quality fatty acid methyl esters (FAME) from waste cooking palm oil (WCO). Continuous transesterification of free fatty acids (FFA) from acidified oil with methanol was carried out using a calcium oxide supported on activated carbon (CaO/AC) as a heterogeneous solid-base catalyst. CaO/AC was prepared according to the conventional incipient-wetness impregnation of aqueous solutions of calcium nitrate (Ca(NO3)2·4H2O) precursors on an activated carbon support from palm shell in a fixed bed reactor with an external diameter of 60 mm and a height of 345 mm. Methanol/oil molar ratio, feed flow rate, catalyst bed height and reaction temperature were evaluated to obtain optimum reaction conditions. The results showed that the FFA conversion increased with increases in alcohol/oil molar ratio, catalyst bed height and temperature, whereas decreased with flow rate and initial water content in feedstock increase. The yield of FAME achieved 94% at the reaction temperature 60 °C, methanol/oil molar ratio of 25: 1 and residence time of 8 h. The physical and chemical properties of the produced methyl ester were determined and compared with the standard specifications. The characteristics of the product under the optimum condition were within the ASTM standard. High quality waste cooking palm oil methyl ester was produced by combination of heterogeneous alkali transesterification and separation processes in a fixed bed reactor. In sum, activated carbon shows potential for transesterification of FFA.

MORPHOLOGY OF NANOSTRUCTURED TiO2 THIN FILM: SYNTHESIS BY ELECTROSTATIC SPRAY DEPOSITION TECHNIQUE AND ITS PHOTOCATALYTIC ACTIVITY

Titanium dioxide (TiO2) thin films with different morphologies were synthesized on glass substrate using an electrostatic spray deposition method. Rod, flake and spherical-like nanostructures of TiO2 porous films with anatase phase could easily be obtained by tailoring the precursor solution concentration for atomization. The photocatalytic degradation of methylene blue in aqueous solution was used as a probe to evaluate their photocatalytic activities. The rod-like nanostructured film produced higher photocatalytic activity than other films. The deposition of thin film photocatalyst on the substrate could not only solve the problem of separation and recovery of catalyst particles from the reaction medium, but also provide high photocatalytic activity even at a low catalyst loading of 0.057 g/l.

Electrically conductive poly(3,4-ethylenedioxythiophene)–poly(styrene sulfonate)/polyacrylonitrile fabrics for humidity sensors

Humidity sensors based on poly(3,4-ethylenedioxythiophene)–poly(styrene sulfonate) (PEDOT–PSS)/polyacrylonitrile (PAN) nanofiber fabric were fabricated by a dip coating of nonwoven PAN nanofiber mat, which was prepared via an electrospinning method, in PEDOT–PSS solution. The influence of PAN solution concentration on their responsiveness to humidity on dynamic testing was monitored as the device was exposed to humidity. With the relative humidity (RH) changing from 0 to 100%, a resistance device response over 110% was achieved, and the curve of the resistance response with RH is of high linearity at the humidity working range of 0–100% RH. The high device reproducibility was demonstrated by carrying out vapor adsorption–desorption dynamic cycles, and the response and recovery times were determined to be of the order of 2–46 and 7–34 s, respectively. These hybrid polymer sensors can be used as disposable handheld instruments due to low cost and light weight.

Architectural control of nanostructured ZrO2 thin films via the electrostatic spray deposition technique using zirconatrane as a precursor

Nanostructures of zirconium dioxide (ZrO2) thin films with different morphologies were deposited on a glass substrate via electrostatic spray deposition, using zirconatrane as a precursor. Structure formation can easily be controlled by tuning the weight ratio of zirconatrane to ethanol without the addition of a stabilizer to the reaction mixture. The ZrO2 structures presented nanoflower- and nanoneedle-like morphologies. Furthermore, the humidity-sensing properties of those sensors based on these thin films were evaluated. Compared with the needle-like sensor, the flower-like ZrO2 sensor has better sensitivity, higher reproducibility and quicker recovery behavior to humidity over a wide range of relative humidity (RH) (0–100% RH).

Fabrication of Ceramic Nanofibers Using Atrane Precursor

One-dimensional (1D) ceramic nanostructures, such as nanofibers, nanotubes, nanorods, nanowires, nanorings, nanobelts, and nanowhiskers, have been a very exciting and promising research topic in the last decades. This interest has been aroused by their unique properties and a wide variety of potential applications in future nanoelectronics and functional nanodevices, such as optoelectronics, photonics, cosmetics, health, bioengineering, gas and humidity sensors, mechanics, and catalysis (Xia et al., 2003; Wang, 2004; Carotta et al., 2007; Kumar & Ramaprabhu, 2007; Luo et al., 2007). A large number of techniques are available to prepare these materials, including vapour-phase method (Pan et al., 2001; Zhang et al., 2002), vapour–liquid–solid method (Morales & Lieber, 1998; Duan & Lieber, 2000), solution–liquid–solid method (Trentler et al., 1995; Markowitz et al., 2001), template-assisted method (Martin, 1994; Han et al., 1997; Zach et al., 2000; Barbic et al., 2002), solvothermal method (Heath & LeGoues, 1993; Wang & Li, 2002), arc discharge (Iijima, 1991), pulsed laser ablation (Sasaki et al., 2004), and precursor thermal decomposition (Wang et al., 2002a). Nevertheless, developing simpler and versatile approaches to the synthesis of one-dimensional ceramic nanostructures still remains a challenge. Among various approaches, electrostatic spinning (electrospinning) seems to be the simplest and most versatile technique capable of fabricating one-dimensional nanostructures including polymer, ceramic and composite nanofibers (Huang et al., 2003, Shao et al., 2003, Ksapabutr et al., 2005a ; Ksapabutr et al., 2005b; Li et al., 2006; Sigmund et al., 2006; Panapoy et al., 2008a; Panapoy et al., 2008b). Like a number of conventional spinning processes, electrospinning involves the ejection of a viscous solution (or melt) from an orifice and the subsequent drawing and solidification of the jet to form thin fibers. Unlike the conventional spinning processes, the exclusive driving force for the formation of ultrafine fiber in the electrospinning process is the electrostatic interaction. The fundamental principle of electrospinning is that a Taylor cone is formed by applying an electrical field to the viscous solution or melt hanging from a capillary tip, which causes jets of an electrically charged solution to be emitted when the applied electrostatic force exceeds the surface tension of the solution. A liquid jet shoots away from the capillary tip towards an oppositely charged electrode and solidifies with evaporation of solvent to form a mat on the grounded