Browsing by Author "Zakaria, Francisca"

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Rheological and physicochemical analysis of non- edible oils used for biodiesel production
(NM-AIST, 2023-07) Zakaria, Francisca
The knowledge of the physicochemical and rheological flow characteristics of biodiesel feedstock is used for quality control in production, storage and transportation processes. Moreover, the knowledge is applied in redesigning and optimizing facilities that can be used for manufacturing, storage and transportation of the fuel. Non-edible oils analysed in the present study were Cashew Nut Shell Liquid (CNSL), Castor Oil (CO), croton megalocarpus oil (CMO), podocarpus usambarensis oil (PUO) and Thevetia peruviana oil (TPO). Free fatty acid, acid value, saponification value, peroxide value, iodine value, specific gravity and moisture content were determined by following the recommended Association of Official Analytical Chemists (AOAC) methods of analysing physicochemical characteristics. Physicochemical results show that all the selected non-edible vegetable oils with an exception of CNSL, do not require any further treatment. However, due to high Free Fatty Acid (FFA) content in CNSL, direct biodiesel production from the feedstock would be a challenge hence further treatment to reduce the acidity of the feedstock is essential. Rheological flow parameters were analysed using VT-550 Thermo Haake Viscotester monitored by a Rheowin Job manager. The pre-set parameters in the Viscotester were the shear rate and temperature. The shear rate was increased uniformly from 5 𝑠−1 –100 𝑠−1 in 60 seconds at 30-60˚C. Regardless of the analysis temperature, all oils exhibited Newtonian flow behavior, indicating that the viscosity of the oil remained uniform at a constant temperature. The experimental data were fitted into rheological models: Newton, Bingham, Oswald de Waele (power-law), and Herschel Bulkley using Rheowin data evaluation software. The results revealed that Newton and Oswald de Waele models were appropriate to represent the flow behaviour of the oils with the fit of R2 ≥ 0.990.
Rheological and Physicochemical Analysis of Nonedible Oils Used for Biodiesel Production
(ACS Omega, 2022-10-13) Zakaria, Francisca; Lujaji, Frank; Kivevele, Thomas
Rheological and physicochemical characteristics of edible oils used for biodiesel production are well established; nonetheless, the rheological and physicochemical characteristics of nonedible oils are yet to be established. The present study therefore focuses on rheological and physicochemical characterization of nonedible vegetable oils that can be used as biodiesel feedstock. The selected vegetable oils studied include cashew nut shell liquid (CNSL), castor oil (CO), Croton megalocarpus oil (CMO), Podocarpus usambarensis oil (PUO), and Thevetia peruviana oil (TPO). Physicochemical parameters analyzed were free fatty acids, acid value, saponification value, peroxide value, iodine value, specific gravity, and moisture content using methods by the Association of Official Analytical Chemists (AOAC). Rheological properties were analyzed using a VT-550 Thermo Haake Viscotester operated by the Rheowin 3 Job Manager software. The preset parameters in the Viscotester were shear rate and temperature. The shear rate increased uniformly from 5 to 100 s–1 at the temperature range of 30–60 °C. The experimental data were fitted into rheological models of Newton, Bingham, Ostwald–de Waele (power-law), and Herschel–Bulkley using Rheowin 3 Data Manager. The oil yield was 29–65%, highlighting the feedstock’s potential for commercial biodiesel production. At a constant temperature, all oil samples exhibited a Newtonian flow behavior. In contrast to edible oils, nonedible oils exhibited high shear stress, emphasizing the reconstruction of new appropriate designs of production systems. The rheological models appropriate to represent the flow behavior of the samples were the Newton and Ostwald–de Waele models, with a fit of R2 = 0.990–1.000.