Antioxidation Behavior Of Zeolite Nanocrystals In Palm Oil: Effect Of Structural Properties And Optimization Studies
| dc.contributor.author | Tan, Kok Hou | |
| dc.date.accessioned | 2017-02-27T02:15:32Z | |
| dc.date.available | 2017-02-27T02:15:32Z | |
| dc.date.issued | 2015-09 | |
| dc.description.abstract | Zeolite X nanocrystals (FAU-type framework structure) with different extra-framework cations (Li+, Na+, K+ and Ca2+) were prepared through ion exchange and their effect on thermal oxidation of palm oil was investigated. The efficiency of zeolite X nanocrystals in slowing down the oil oxidation rate was associated to the cations polarizability, framework basicity and charge density (Li+< Na+< Ca2+≤ K+). Li-X containing zeolite with the lowest cation polarizability was found to have the lowest oxidative inhibition activity, while highly basic and highly polarized zeolite K-X was the best candidate to hinder oil oxidation. The zeolite nanocrystals decelerate oxidation in palm oil through stabilization of hydroperoxides and concurrently via adsorption of secondary oxidation products (alcohols, aldehydes, ketones, carboxylic acids, and esters). Unlike monovalent alkali metal cation exchanged zeolites, the Ca-X also reduced the acidity in oil by neutralizing the acidic carboxylate compounds to COO–(Ca2+)1/2 species. The quality and the oxidative stability of palm oil in the presence of zeolite nanocrystals with different structural framework (EMT-, FAU- and LTL) are also investigated. The results indicate that hydrophilic nanosized FAU-type zeolite shows the best performance in slowing down the oxidation rate of palm oil via efficiently limiting the production rate of water and black polymeric residues. This is due to the fact that the presence of acidic organic products and polymeric residues may increase the degradation rate of the palm oil. In this particular example, the IR spectroscopy data demonstrate that zeolite nanoparticles are able to stabilize the oxidative propagation agent such as hydroperoxides, and hence limiting the polymerization products. A mechanism describing the inhibition of oil oxidation by zeolite nanoparticles is proposed. It can be explained by the adsorption and stabilization of oxidized intermediate species, which are facilitated by the electrostatic interaction between C=O and O‒O‒H groups of oxidized species with the hydrophilic zeolite framework. Therefore it is suggested that the hydrophilic nanosized zeolites improve the lifetime of palm oil, and they are potential candidates to be eco-friendly antioxidant additives in replacing the conventional harmful organic antioxidant in the oil industry. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3782 | |
| dc.language.iso | en | en_US |
| dc.publisher | Universiti Sains Malaysia | en_US |
| dc.subject | The zeolite nanocrystals decelerate | en_US |
| dc.subject | oxidation in palm oil. | en_US |
| dc.title | Antioxidation Behavior Of Zeolite Nanocrystals In Palm Oil: Effect Of Structural Properties And Optimization Studies | en_US |
| dc.type | Thesis | en_US |
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