Papers by Author: R. Watanesk

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Authors: P. Moonsri, S. Watanesk, R. Watanesk, H. Niamsup, Q. Cheng, R.L. Deming
Abstract: Stable silk fibroin (SF) membranes were prepared by modifying SF with polyethylene glycol diglycidyl ether (PEGDE) for use as enzyme immobilizing matrix. Morphology, structure, and water solubility of the modified silk fibroin (MSF) membrane were investigated. SEM images revealed greater porosity in the MSF membranes. IR spectra confirmed the predominant β-sheet conformation when the PEGDE was greater than 4%. In addition, the MSF membranes were highly insoluble within the pH range 4 10. An amperometric glucose biosensor was initially constructed using glucose oxidase (GOx) immobilized on the MSF membrane, coupled to a Prussian Blue (PB) deposited Au electrode. The response characteristics of the biosensors based on the GOx immobilized onto the 4% and 8% PEGDE modified SF membranes (4P-MSF and 8P-MSF) and the methanol treated SF membrane (MT-SF) were investigated. Amperometric measurements at the applied potential of 0.0 V demonstrated that the glucose biosensor based on the GOx immobilized onto the 4P-MSF membrane exhibited high sensitivity to glucose with a short response time, less than 3 s. Moreover, the stability of the biosensors based on the 4P-MSF membranes was better than those based on the MT-SF membrane after 2 weeks of storage in a phosphate buffer of pH 7.0 at 4 °C. These fundamental electroanalytical features of the sensor are therefore expected to be useful in biosensor application
Authors: S. Janta, S. Watanesk, R. Watanesk, Sakdiphon Thiensem
Abstract: In this study, the uptake of fluoride by raw diatomite and diatomite activated by heat treatment was investigated. Influential parameters such as contact time, pH and adsorption isotherm were also studied. The results showed that the diatomite heated to 500 oC performed better than other heat treatment products and the equilibration time needed for fluoride removal by the adsorbents was reached at 60 min. Results revealed that the capacity of the adsorbents for removing fluoride is independent of the pH when the pH is higher than 4. The adsorption isotherm of the 500 oC treated diatomite showed its Langmuir behavior. The maximum adsorption capacity of raw diatomite and 500 oC calcinated diatomite are 2.253 and 4.162 mg/g, respectively. Based on the results it can be concluded that the diatomite appears to be an economical and environmentally friendly material for defluoridation of water.
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