Time filter

Source Type

Jamnongkan T.,Kasetsart University | Wattanakornsiri A.,Surindra Rajabhat University | Wachirawongsakorn P.,Phitsanulok University | Kaewpirom S.,Burapha University
Polymer Bulletin | Year: 2014

Recently, a renewed interest in hydrogels for heavy metal removal of wastewater has been growing because of embarking opportunities in industrial applications. One of the most interesting hydrogels potentially used as absorbent is poly(vinyl alcohol) (PVA), owing to its biocompatibility. In this study, the adsorption capacity of copper(II) ion onto PVA hydrogel (PVAH) adsorbents with different crosslinking degrees of 1, 3 and 5 % from aqueous solution was investigated. The PVAH adsorbents were prepared from PVA, using glutaraldehyde as a crosslinking agent. Their properties were determined by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water absorption measurement. The results showed that PVA was crosslinked with glutaraldehyde. It exhibited an equilibrium swelling ratio in the range of 195-250 %, depending on the crosslinking degree with different PVAH structures defined from SEM micrographs. The adsorption capacity of copper(II) ion onto PVAH adsorbents was investigated and found that higher crosslinking degree decreased the absorption capacity. This behavior is due to the decrease in reactive sites, resulting in the decrease of interaction between copper(II) ion and PVA. Besides, the adsorption capacity also depended on contact time, pH and temperature. The adsorption process followed pseudo-second-order kinetic, having a 0.99 correlation coefficient. Intraparticle diffusion was confirmed by the adsorption mechanism controlled by particle and film diffusions. © 2014 Springer-Verlag Berlin Heidelberg.

Phuengphai P.,Surindra Rajabhat University | Youngme S.,Khon Kaen University | Chaichit N.,Rangsit University | Reedijk J.,Leiden University | Reedijk J.,King Saud University
Inorganica Chimica Acta | Year: 2013

Two new metal-organic frameworks, {[Zn(dpe)(μ-OOCCH3) 2](H2O)}n (1) and {[Zn3(dpe) 4(μ-OOCC2H5)4](dpe)(ClO 4)2}n (2) (dpe = 1,2-bis(4-pyridyl)ethene), have been prepared and investigated. Their structures were determined by X-ray crystallography. The different structures of both compounds indicate that the different steric constraints for a methyl group (acetato, compound 1) and an ethyl group (propionato, compound 2), as well as the counteranion effects (ClO4 - for 2), play an important role in the formation and structure of these coordination polymers. Compound 1 exhibits a 1D zig-zag polymeric chain based on mononuclear secondary building units. The replacement of the acetate by propionate ligands, in the presence of additional ClO 4 - during the synthesis procedure, gives rise to a 2D network that is assembled from trinuclear secondary building units (compound 2). In addition, both compounds are further stabilized by π-π interactions and by hydrogen bonds to form intricate supramolecular frameworks. The 1D (1) and 2D (2) networks exhibit voids that contain guest water molecules for compound 1 and perchlorate/dpe for compound 2. Both coordination compounds have been structurally characterized and the thermal stability, potential cation-exchange and selected catalytic properties have been investigated. Interestingly, both Zn(II) compounds act as active heterogeneous catalysts for the high-yield cyanosilylation of acetaldehyde in dichloromethane and show highly size-selective properties for the substrate benzaldehyde. The metal sites in each compound have been studied in some more detail by using doped species with Mn(II) and Cu(II) and the EPR properties. © 2013 Elsevier Ltd. All rights reserved.

Thinvongpituk C.,Ubon Ratchathani University | Arayangkun S.,Surindra Rajabhat University
Applied Mechanics and Materials | Year: 2012

Friction welding is a welding technique that has been studied and developed continuously. This is due to its advantages, such as it provides high quality of joint, high strength of joint. It can make welded zone through the whole section without bubble. However, there is heat generated in the welding process that can change the phase of materials. Hence, the hardness and strength of joint are affected. This paper is aimed to investigate the microstructure at the joint, which is called heat affected zone. The experiment was conducted with a number of steel rods of 10 mm. diameter. The welded specimens were tested for strength, hardness and microstructure. The temperature gradient of specimen under welding process was also recorded. It was revealed that the strength of welded element is higher but the hardness is lower. The photo of thermo scan revealed that heat is generated around the lip of interface, resulting high temperature in heat affected zone. This causes some change in microstructure composition as well as joint property. © (2012) Trans Tech Publications, Switzerland.

Phuengphai P.,Surindra Rajabhat University | Phuengphai P.,Khon Kaen University | Phuengphai P.,Leiden University | Youngme S.,Khon Kaen University | And 3 more authors.
Inorganic Chemistry Communications | Year: 2012

A new porous coordination polymer, i.e. the two-dimensional layered network {[Cu 3(4,4′-bpy) 3(μ-OOCH) 4(H 2O) 2](BF 4) 2(H 2O) 6} n has been synthesized from Cu(BF 4) 26H 2O, 4,4′-bpy and with formate as co-ligand. Single-crystal X-ray diffraction analysis reveals a (4,4) 2D coordination network exhibiting voids that contain the counter-ions and water guest molecules. In addition, the title compound is further stabilized by hydrogen bonds and anion-π interactions to form an intricate supramolecular framework. The removal and reintroduction of guest water molecules has been explored to better understand the dynamic structural transformation. The coordination compound shows weak catalytic activity in the cyanosilylation of aldehydes. © 2012 Elsevier B.V. All rights reserved.

Yoonaiwong W.,Ubon Ratchathani UniversityUbon Ratchathani | Kaewsarn P.,Ubon Ratchathani UniversityUbon Ratchathani | Reanprayoon P.,Surindra Rajabhat University
Sustainable Environment Research | Year: 2011

Biosorption of Pb(II) and Cd(II) ions by non-living macrophytes, Utricularia aurea has been investigated as a function of initial pH, contact time and metal concentrations. Adsorption kinetic and equilibrium tests were carried out in flasks under batch operations. The adsorption data obtained under optimum condition were evaluated by Freundlich and Langmuir isotherm. The biosorption kinetic results have shown that Pb(II) and Cd(II) ions removal rate was at its maximum at the beginning of the process. The equilibrium state was achieved after 30 min for lead and 90 min for cadmium. When experiments were performed with different desorbents the results indicated that 0.1 M HCl was an efficient desorbent for recovery of metal ions from biomass. In addition, Fourier transform infrared spectroscopy (FTIR) spectroscopy was done to identify the chemical functional group present on the biomass. The surface structure of biomass was analyzed by scanning electron microscopy (SEM). The biosorption mechanism of biosorbent was also evaluated by FTIR and SEM. © 2011, Chinese Institute of Environmental Engineering. All rights reserved.

Pathomsiriwong W.,Surindra Rajabhat University | Reanprayoon P.,Surindra Rajabhat University
Journal of Environmental Science and Technology | Year: 2012

The aim of this research was to develop a low cost adsorbent for the acid dye wastewater treatment. The non-living aquatic macrophytes, Hydrilla verticillata has been investigated as a function of initial pH, contact time and initial concentrations. Adsorption kinetic and equilibrium tests were carried out in flasks under batch operations. Optimum decolorization was observed at pH 3.0 and the equilibrium state was achieved after 80 min. the pseudo-first-order and the pseudo-second-order kinetics were investigated for the biosorption system. Isotherm data can be described reasonably well with the Langmuir isotherm. In adhtion, Scanning electron microscope of pre-treated biomass shows that surface of the biomass with CaCl2 solution would remove the fine agglomerates and other surface impurities from the surface of biomass and Energy dispersive X-ray spectroscopy analysis released that pre-treated biomass was significant difference in ion exchange as K+ and Cu2+ between un-treated biomass and pre-treated biomass. FTIR spectroscopy was employed to identify the chemical functional group present on the biomass. The characteristics bands of H. verticillata biomass are attributed to chemical bonds belonpng to protein and polysaccharides functional groups. The experimental results in this study indicated that this low-cost biomaterial was an attractive candidate for the removal of acid dye from aqueous solutions at even low concentration. © 2012 Asian Network for Scientific Information.

Wiwanitkit V.,Surindra Rajabhat University
North American Journal of Medical Sciences | Year: 2014

Ebola virus infection is the present global consideration. This deadly virus can result in a deadly acute febrile hemorrhagic illness. The patient can have several clinical manifestations. As a new emerging infection, the knowledge on this infection is extremely limited. The interesting issues to be discussed include a) the atypical clinical presentation, b) new diagnostic tool, c) new treatment, and d) disease prevention. Those topics will be discussed in this special review. © 2014, North American Journal of Medical Sciences. All rights reserved.

Stanner M.,Surindra Rajabhat University
Hamadryad | Year: 2012

Recurrent laborious attempts by Varanus salvator to swallow a walking catfish (Clarias sp.) posterio-anteriorly are described. This feeding behaviour is interpreted as a trade-off between immediate gains, i.e. a presumably easy and quick anterior-posterior swallowing and a laborious and lengthy posterior-anterior swallowing, but more secure in the long-run, i.e. in cases of emergency, an anterio-posteriorly swallowed catfish may not be ejected or regurgitated quickly enough (or not at all) due to the backwards pointing spines of the pectoral fins. This trade-off is interpreted as another facet of the life-dinner principle unrelated to its original implication in predator-prey coevolution.

Phuengphai P.,Surindra Rajabhat University | Phuengphai P.,Khon Kaen University | Phuengphai P.,Leiden University | Massera C.,University of Parma | And 4 more authors.
European Journal of Inorganic Chemistry | Year: 2013

Six coordination polymers, namely, the three-dimensional frameworks {[Zn3(4,4′-bpy)3.5(μ-O2CH) 4(H2O)2](ClO4)2(H 2O)2}n (1, 4,4′-bpy = 4,4′-bipyridine) and {[Zn3(4,4′-bpy)3.5(μ- O2CH)4(H2O)2](PF6) 2}n (2), the two-dimensional networks {[Zn(4,4′-bpy) (μ-O2CH)(H2O)2](CF3SO 3)(H2O)}n (3) and {[Zn3(4,4′- bpy)4(μ-O2CCH2CH3) 4](ClO4)2(4,4′-bpy)2(H 2O)4}n (4), the one-dimensional double-stranded zigzag chain {[Zn3(4,4′-bpy)4(μ-O 2CCH2CH3)4(H2O) 2](PF6)2(H2O)2} n (5), and the one-dimensional double-ladder chain {[Zn 2(4,4′-bpy)2(μ-O2CCH 2CH3)2(H2O)2](CF 3SO3)2}n (6), have been prepared. The solid-state structures of the six compounds all exhibit void spaces that contain anions and neutral guest molecules, namely, water for 1, 3 and 5, and water/4,4′-bpy for 4. The anion-exchange properties of the compounds have been investigated by monitoring the substitution of the ions by infrared spectroscopy. Furthermore, X-ray powder diffraction studies and elemental analyses have been used to further confirm the anion exchange. The results show that the anions in all compounds can be replaced with ClO4 - or PF6 - for 1, 2, 4, and 5, ClO 4 - and PF6 - for 3, and ClO 4 -, PF6 -, and BF4 - for 6. Furthermore, compound 1 shows interesting reversible anion-exchange properties in aqueous solution. A series of cationic extended coordination frameworks exhibits anion-exchange properties for a variety of inorganic anionic species. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reanprayoon P.,Surindra Rajabhat University | Yoonaiwong W.,Surindra Rajabhat University
Aerobiologia | Year: 2012

Thailand border market is where the local Thais, Cambodians, Laotians, and Burmeses exchange their goods and culture at the border checkpoints. It is considered to be the source of aerial disease transmission especially for foreigners because it is always very crowded with people from all walks of life. Unhealthy air quality makes this area high risk of spread of airborne diseases. This study assessed airborne concentrations of bacteria and fungi in a border market to improve exposure estimates and develop efficient control strategies to reduce health risk. The density and distribution of airborne bacteria and fungi were investigated in the Chong Chom border market in Surin Province, Thailand. Eighteen air sampling sites were taken from outdoors and various work environments including indoor footpaths, wooden handicraft shops, electronic shops, the secondhand clothing shops, and fruit market areas. Exposed Petri plate method and liquid impinger sampler were used for sampling at the breathing zone, 1.5 m above the floor level, during weekend and holiday. Meteorological factors such as relative humidity, temperature, and light intensity were collected by portable data logger. The relative humidity was 67-73%, and temperature 29-33°C, and light varied between 18 and 270 Lux m -2. Gram-positive and Gram-negative bacteria were found at a mean value of 10 4 CFU m -3, and airborne fungi of 10 3 CFU m -3 were recorded. The highest concentration of culturable airborne microorganisms was found along the indoor footpath (9.62 × 10 4 CFU m -3 and 750.00 CFU/plate/h for impingement and sedimentation methods, respectively), the fruit market area (7.86 × 10 4 CFU m -3 and 592.42 CFU/plate/h for impingement and sedimentation methods, respectively), and the secondhand clothing shop (4.59 × 10 3 CFU m -3 and 335.42 CFU/plate/h for impingement and sedimentation methods, respectively) for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The lowest concentration of Gram-positive bacteria, Gram-negative bacteria, and fungi was found only at the outdoor area at 1.53 × 10 4 CFU m -3, 0.93 × 10 4 CFU m -3 and 0.80 × 10 3 CFU m -3 by means of impingement method and 136.67 CFU/plate/h, 69.25 CFU/plate/h, and 62.00 CFU/plate/h by means of sedimentation methods for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The most frequently present airborne bacteria were identified as Bacillus, Corynebacteria, Diplococcus, Micrococcus, Acinetobacter, Alcaligenes, Enterobacter, and spore former rods. Acremonium, Aspergillus, Cladosporium, Penicillium, and Sporotrichum were the most frequently found aerosol fungi genera. The distribution of airborne microorganisms correlated with relative humidity and light factors based on principal component analysis. In conclusion, the border market is a potential source of aerial disease transmission and a various hazards of bioaerosols for workers, consumers, sellers, and tourists. The bioaerosol concentration exceeded the standard of occupational exposure limit. Many major indicators of allergenic and toxigenic airborne bacteria and fungi, Acinetobacter, Enterobacter, Pseudomonas, Cladosporium, Alternaria, Aspergillus, and Penicillium, were found in the various market environments. © Springer Science+Business Media B.V. 2011.

Loading Surindra Rajabhat University collaborators
Loading Surindra Rajabhat University collaborators