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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. Source


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. Source


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. Source


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. Source


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. Source

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