Rajamangala University of Technology at Krungthep

Bangkok, Thailand
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Samart C.,Thammasat University | Chaiya C.,Rajamangala University of Technology at Krungthep | Reubroycharoen P.,Chulalongkorn University
Energy Conversion and Management | Year: 2010

The transesterification of soybean oil with a CaO/mesoporous silica catalyst was achieved. The effects of CaO loading levels in the mesoporous silica catalyst, the amount of catalyst to substrate level and the reaction temperature and time on the conversion of soybean oil were investigated. Increasing the temperature and reaction time raised the total conversion of soybean oil attained. The optimized condition, found to be 15 wt.% of Ca loading on the mesoporous silica catalyst, a 5% (w/w) catalyst to oil level and a reaction temperature of 60 °C for 8 h, provided the highest yield of 95.2%. The fuel properties of the biodiesel obtained under these optimized conditions were acceptable under the biodiesel standards of Thailand. © 2010 Elsevier Ltd. All rights reserved.

Kampeerapappun P.,Rajamangala University of Technology at Krungthep
Chiang Mai Journal of Science | Year: 2012

In this study, cellulose electrospun nanofibers were prepared directly from cotton waste fiber solution via electrospinning at room temperature. The effects of solution concentration and applied voltage on morphology of electrospun nanofibers were investigated. It was observed that the fiber diameter was strongly affected by the concentration of polymer solution and applied voltage. Analysis of the fourier transform infrared spectroscopy (FT-IR) spectra demonstrated that cotton fibers and cellulose electrospun nanofibers showed the same characteristic functional groups. X-ray diffraction (XRD) revealed that the crystallinity of the cellulose was reduced after electrospinning. Then, an antimicrobial agent solution, 3-(trimethoxysilyl) propyldimethyl octadecyl ammonium chloride (AEM), was treated on cellulose electrospun nanofiber mats. All treated electrospun nanofiber mats showed better uniformity and % extraction compared with untreated mats. These electrospun nanofiber mats exhibited excellent antibacterial activities against Staphylococcus aureus (S. aureus) from 2% w/w antimicrobial agent.

Poonjarernsilp C.,Kyoto University | Poonjarernsilp C.,Rajamangala University of Technology at Krungthep | Sano N.,Kyoto University | Tamon H.,Kyoto University
Applied Catalysis B: Environmental | Year: 2014

Four carbon-based solid acid catalysts were prepared from single-walled carbon nanohorns (SWCNHs), oxidized SWCNHs (ox-SWCNHs), activated carbon (AC), and carbon black (CB) by hydrothermal sulfonation at 200°C in an autoclave reactor. N2 adsorption analysis suggested that sulfonation treatment leads to a drastic reduction in the number of relatively large pores with diameters greater than 20nm in the SWCNHs and ox-SWCNHs. In addition, the BET surface area of the SWCNH was doubled by this sulfonation. These structural changes were not observed in AC and CB. The acid functional group formed on these solid catalysts by sulfonation was speculated to be -SO3H, and this was analyzed by ion-exchange titration. From the results, it was found that sulfonated SWCNHs (SO3H-SWCNHs) had the highest acid density of the four sulfonated specimens, which is a desirable property for its use as a biodiesel production catalyst. Methyl palmitate, a kind of biodiesel, was produced by the esterification of palmitic acid using these four catalysts. SO3H-SWCNHs produced the highest yield and the catalytic activity was significantly higher than that using a homogeneous sulfuric acid catalyst. Repeated esterification experiments suggested that the acid sites on SO3H-SWCNHs and SO3H-ox-SWCNHs were more stable than those on SO3H-AC and SO3H-CB. © 2013 Elsevier B.V.

Nakpong P.,Rajamangala University of Technology at Krungthep | Wootthikanokkhan S.,Rajamangala University of Technology at Krungthep
Renewable Energy | Year: 2010

Coconut oil having 12.8% free fatty acid (FFA) was used as a feedstock to produce biodiesel by a two-step process. In the first step, FFA level of the coconut oil was reduced to 0.6% by acid-catalyzed esterification. In the second step, triglycerides in product from the first step were transesterified with methanol by using an alkaline catalyst to produce methyl esters and glycerol. Effect of parameters related to these processes was studied and optimized, including methanol-to-oil ratio, catalyst concentration, reaction temperature, and reaction time. Methyl ester content of the coconut biodiesel was determined by GC to be 98.4% under the optimum condition. The viscosity of coconut biodiesel product was very close to that of Thai petroleum diesel and other measured properties met the Thai biodiesel (B100) specification. © 2009 Elsevier Ltd. All rights reserved.

Kampeerapappun P.,Rajamangala University of Technology at Krungthep
Journal of Applied Polymer Science | Year: 2016

Polyhydroxybutyrate (PHB) has been used in the biomedical field. However, the poor mechanical properties of PHB have limited its application. Here, electrospun fibrous nanocomposite mats reinforced with cellulose nanocrystals (CNCs) were fabricated by using PHB as polymeric matrix. The morphological, thermal, mechanical properties, as well as cytotoxicity were characterized. Increasing the concentration of CNCs caused a decrease in diameter of the electrospun fibers. Moreover, thermal analysis indicated that melting temperature of PHB/CNCs electrospun fibers were improved with the increased CNCs content. The addition of CNCs gradually enhanced the tensile strength till 8 wt % content followed by a gradual decrease at higher CNCs content (12-22 wt %) in tensile strength. The PHB/CNCs electrospun fibers were nontoxic to L-929 and capable of supporting cell proliferation in all conditions. This study demonstrates that fibrous PHB/CNCs electrospun fibers are cytocompatible and potentially useful mechanical properties for biomedical application. © 2016 Wiley Periodicals, Inc.

Kusuktham B.,Rajamangala University of Technology at Krungthep
Journal of Applied Polymer Science | Year: 2012

The spinning of poly(ethylene terephthalate) (PET) filaments in laboratory-scale was studied. The objective was to study the effect of modified calcium silicate (CS) with vinyltriethoxysilane (VTES) on the melt spinning of PET fibers. The CS was modified with VTES (2% v/v) in diethyl ether at room temperature for 24 h. The modification of CS with VTES improved agglomeration of CS, hydrophobic, and heat-resistance properties. These properties were expected that modified CS could be used as the filler in melt spinning of PET. The incorporation of modified CS in PET was spinnable. The addition of CS in PET improved its heat resistance. Also, the filler had an effect on the mechanical properties of polyester fibers. © 2011 Wiley Periodicals, Inc.

Kusuktham B.,Rajamangala University of Technology at Krungthep
Journal of Applied Polymer Science | Year: 2012

Poly(ethylene terephthalate) (PET)/inorganic fillers were prepared by a melt-spinning method, and their morphologies and properties were investigated. Four inorganic fillers were studied and compared: calcium carbonate, calcium silicate, magnesium hydroxide, and silica fume. All of the fillers were modified with vinyltriethoxysilane (VTES) in diethyl ether at room temperature for 24 h. The modification of these fillers with VTES improved their agglomeration, hydrophobicity, and heat-resistance properties. Also, the incorporation of the fillers into the PET fibers increased their thermal resistance. The factor effecting the thermal degradation of the PET fibers was the type of filler. © 2012 Wiley Periodicals, Inc.

Choedkiatsakul I.,Chulalongkorn University | Ngaosuwan K.,Rajamangala University of Technology at Krungthep | Assabumrungrat S.,Chulalongkorn University
Fuel Processing Technology | Year: 2013

This research investigated the application of commercial heterogeneous catalysts i.e., calcium oxide (CaO) and potassium phosphate (K 3PO4) for biodiesel production in an ultrasound-assisted reactor (US). For comparison, the results from the use of homogeneous catalysts i.e., sodium hydroxide (NaOH) and sulfuric acid (H2SO4) as well as from the use of conventional mechanical stirred reactor (MS) were also studied. High methyl ester yields were achieved in the US reactor for both CaO (90%) and K3PO4 (80%). The mixing characteristics generated from US and MS reactors resulted in the different performance (activation and deactivation) of CaO and K3PO4 catalyzed transesterification. The major overcome of using US reactor for heterogeneously catalyzed transesterification was found in the catalyst reusability test. Methyl ester yield of CaO catalyst gradually reduced when applying US reactor compared to MS reactor, particularly in the last cycle. The dissolution effect was more severe when employing K3PO4 catalyst in the MS reactor due to the mechanical stress and the mixing characteristic effects. Therefore, the use of US reactor did not only provide the high methyl ester yield in a short reaction time but also showed the hindrance of dissolution compared to the MS reactor. It can be concluded that the heterogeneously catalyzed transesterification in US reactor was not only favorable in the activation but also diminishable in the deactivation of solid catalysts. © 2013 Elsevier B.V.

Nakpong P.,Rajamangala University of Technology at Krungthep | Wootthikanokkhan S.,Rajamangala University of Technology at Krungthep
Fuel | Year: 2010

The production of biodiesel fuel from crude roselle oil was evaluated in this study. The process of alkali-catalyzed transesterification with methanol was carried out to examine the effects of reaction variables on the formation of methyl ester: variables which included methanol-to-oil molar ratios of 4:1-10:1, catalyst concentrations of 0.25-2.0% w/w of oil, reaction temperatures of 32-60 °C, and reaction times of 5-80 min. The methyl ester content from each reaction condition was analyzed by gas chromatography (GC), the optimum condition having been achieved at a methanol-to-oil molar ratio of 8:1, a catalyst concentration of 1.5% w/w of oil, a reaction temperature of 60 °C, and a reaction time of 60 min. The resultant methyl ester content of 99.4% w/w, plus all of the other measured properties of the roselle biodiesel, met the Thai biodiesel (B100) specifications and international standards EN 14214:2008 (E) and ASTM D 6751-07b, with the exception of a higher carbon residue and lower oxidation stability. © 2010 Elsevier Ltd. All rights reserved.

Israngkura Na Ayudhya B.,Rajamangala University of Technology at Krungthep
Materials and Structures/Materiaux et Constructions | Year: 2015

This paper described the results of an extensive experimental study on the comparative between compressive and splitting tensile behavior of autoclaved aerated concrete (AAC) containing water hyacinth fibre (WHF) with AAC mixed with polypropylene (PP) fibre. The specimens of AAC-WHF and the AAC-PP were subjected to elevated temperatures (100, 200, 400, 800 and 1000 °C). Test results indicated that an optimum water hyacinth and PP fibre dosage was at 0.5 and 0.75 % by volume respectively. The maximum residual in compressive strength and the splitting tensile strength of AAC-WHF and AAC-PP were 0.43 and 0.16 N/mm2 and 0.51 and 0.18 N/mm2 respectively. In addition, the loss in residual strength of AAC mixed PP fibre was slower than AAC mixed WHF. The splitting tensile strength of AACs was more sensitive to high temperatures than the compressive strength. A severe strength loss was observed for all of the AAC after exposure to 800 °C. Based on the test results, it can be concluded that the addition of PP fibers can significantly promote the residue mechanical properties of AAC during heating. © 2015 RILEM

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