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Title:	Response surface methodology on palm kernel oil-based polyolester biolubricant synthesis
Authors:	Murad Awadh Salem Bahadi (P90677)
Supervisor:	Darfizzi Derawi, Assoc. Prof. ChM Dr.
Keywords:	Palm kernel Biolubricant Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	27-Jun-2021
Description:	Biolubricant is crucial to be developed considering the toxicity risk, climate change, energy security as well green-environmental approach by using renewable resources. A series of polyol esters-based biolubricants were synthesized through homogeneous acid catalysed transesterification and esterification of crude palm kernel oil (CPKO) and its fatty acids (CPKFAs) with selected polyhydric alcohols; trimethylolpropane (TMP), di trimethylolpropane (Di-TMP), pentaerythritol (PE), and di-pentaerythritol (Di-PE). The optimization of reaction parameters was conducted via response surface methodology (RSM) by D-optimal design. Transesterification of CPKO with TMP and Di-TMP produced 83.9 ±0.8% of CPKO-TMPTE with 99.5 ±0.3% selectivity and 79.1±0.3% of CPKO-Di-TMPTE with 91.4±0.7% selectivity. While, the esterification process of CPKFAs with TMP, Di-TMP, PE, and Di-PE were performed in the presence of sulphuric acid catalyst. Esterification of CPKFAs with TMP produced 86.1±0.7% yield of CPKFAs-TMP triesters with 99.1±0.4% selectivity. The chemical structures of synthesised products were characterized using FTIR and NMR (1H- and 13C-) spectroscopy analysis techniques. The FTIR spectra showed the presence of carbonyl peaks (C=O, C–O) of ester group at wavenumber of 1732–1745 cm−1 and 1166–1251 cm−1. The 1H-NMR spectra confirmed the proton chemical shifts (-CH2-O-C=O) of ester group at 3.69–4.04 ppm, secondary carbons (-CH2-C=O, 2°) at 2.20-2.30 ppm, and unsaturated aliphatic carbons (HC=CH) at 5.30-5.35 ppm. Besides, the 13C NMR spectra confirmed the carbon chemical shifts of carbonyl ester signals at 173.0 -173.5 ppm, quaternary carbons (–C–, 4°) at 40.5 - 42.8 ppm, and (C=C) at 129 -130.5 ppm with different intensities. CPKO-TMPTE showed good thermal stability at 352 oC, pour point at -5 oC, flash point at 315 °C, and viscosity index of 138.74. CPKO-Di-TMPTE showed higher thermal stability at 392 oC, pour point at -6 oC, flash point at 365 °C, and viscosity index of 140.1. The CPKFAs-TMP triesters have moderate oxidative stability at 248.3 °C, high thermal stability at 376.9 °C, pour point at -10 °C, flash point at 320 °C, and viscosity index of 154.8. The CPKFAs-Di-TMP tetraesters (83.23±0.5% yield and 92.7±0.5% selectivity) recorded oxidative stability at 251.8°C, thermal stability at 431.35°C, pour point at -5°C, flash point at 360°C, and viscosity index of 142.37. The CPKFAsPE tetraesters (85.9±0.8 % yield and 95.2±0.5 selectivity) showed oxidative stability at 214.6 °C, thermal stability at 399.3 °C, pour point at -8 °C, flash point at 345 °C, and viscosity index of 140.86. While CPKFAs-Di-PE hexaesters (73±0.7% yield and 92.7±1.6% selectivity) has oxidative stability at 204.65 °C, thermal stability at 440.9°C, pour point at - 5°C, flash point at 420 °C, and viscosity index of 130.6. The results showed that the CPKFAs-Di-PE hexaesters recorded the highest thermal stability value and flashpoint due to the increase in the carbon chains' length and molecule weight. The CPKFAs-TMP triesters have the highest viscosity index. All biolubricant products can be categorised as ISO VG 46 (CPKFAs-TMP triester), ISO VG 68 (CPKO-TMPTE, CPKFAs-Di-TMP tetraesters, CPKFAs-PE tetraesters), ISO VG 100 (CPKO-DiTMPTE), and ISO VG 150 (CPKFAs-Di-PE hexaesters) lubricant grades. The polyolesters recorded their tribological properties with low-friction coefficient range of 0.17–0.19 μ at 40 °C and 0.20–0.27 μ at 100 °C, with Newtonian fluids behaviour. The synthesised polyol esters biolubricants were compatible with some selected commercial lubricants, make them plausible for various industrial applications such as gear, hydraulic and heavy machinery usage in tropical countries at the medium-range operation temperature. ,Ph.D.
Pages:	363
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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