Browsing by Author "Lin, Ong Hui"

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Design of size-tunable molecularly imprinted polymer for selective adsorption of acetaminophen
(2017-01)
Lee, Shih-Hui
;
Lin, Ong Hui
;
doong, Ruey-an
;
環境工程研究所
;
Institute of Environmental Engineering
Pharmaceutical and personal care products are a broad and diverse group of biologically active compounds which are widely used and unregulated suspected carcinogens. In this study, the fabrication of molecularly imprinting polymer (MIP) particles by precipitation polymerisation were developed to selectively and rapidly capture acetaminophen, a commonly used analgesic and antipyretic drug, by hydrogen and hydrophobic bondings. Methacrylic acid, 3-(trimethoxysilyl) propyl methacrylate and 2, 2\'-azobis-isobutyronitrile were utilised as the functional monomer, cross-linker and initiator. Acetonitrile was found to be the optimised porogen to obtain imprinted polymers with surface area and pore size of 447.2 m(2)/g and 3.35 nm. By adjusting the ratio of cross-linker and functional monomer, the particle size of MIPs changed from 177 to 2782 nm when the ratio increased from 0.43 to 12.8. In addition, the adsorption equilibrium of acetaminophen by MIPs can be reached within the first 30 min because of the surface imprinting characteristics and small particle sizes. In addition, the maximum adsorption capacity of acetaminophen and the adsorption constant, well fitted by Langmuir equation, were 0.35 mg/g and 0.045 L/mg. In addition, the MIPs exhibited the excellent selectivity to acetaminophen. The high surface area and adsorption capacity and excellent selectivity make MIPs an ideal tailor-made green material and can open the door to develop the novel technology for adsorption and removal of pharmaceutical and personal care products in the environment.
Unveiling the thermal kinetics and scissoring mechanism of neolatry polyethylene/reduced graphite oxide nanocomposites
(2017-01-01)
Yee, Toh Guat
;
Lin, Ong Hui
;
Bindumadhavan, Kartick
;
Doong, Ruey-an
;
環境工程研究所
The present study focuses on thermal degradation mechanism of low density polyethylene (LDPE)/reduced graphite oxide (rGO) nanocomposites prepared by solvent cast method with an implication of its kinetics modelling. Graphite oxide (GO) was reduced under solvothermal conditions, using sodium borohydride and 0.1, 1.0, 3.0 and 5.0 wt% of rGO was incorporated into LDPE. Thermogravimetric analysis (TGA) was used to determine the decomposition kinetics of the nanocomposites at different heating rates of 1, 5, 10 and 20 degrees C/min. The maximum activation energy (Ea) calculated using Kissinger (K) and Flynn-Wall-Ozawa (FWO) models were noted to be 321.80 and 335.01 kJ/mol respectively at nanocomposite with 3 wt% rGO content. Also, the correlation coefficient (r(2)) in FWO models was higher than 0.95, confirming a single-step decomposition in the nanocomposites. TGA coupled with gas chromatography (GC) and mass spectroscopy (MS) was employed to separate the evolved compounds into alkane, alkene and aromatic groups. Interestingly, pravastatin, a useful gaseous compound was detected at 370 degrees C and other toxic gases were evolved at degradation temperature similar to 460 degrees C and above. Our findings on kinetics behaviour and degradation mechanism emphasize on the thermal cracking characteristic of the LDPE/rGO nanocomposites, which can be utilized to extract useful gaseous components for pharmaceutical application. (C) 2017 Elsevier B.V. All rights reserved.