METHYL ESTERS OF NEEM (AZADIRACHTA INDICA) SEED OIL: PREPARATION, CHARACTERIZATION AND PROCESS OPTIMIZATION

AUTHOR: IKUEZE IFUNANYA CYNTHIA

DEPARTMENT: CHEMICAL ENGINEERING

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

Environmental concerns and limited amount of petroleum resources have caused interests in the development of alternative fuels for internal combustion (IC) engines. As an alternative, biodegradable, renewable and low sulphur biodiesel is receiving increasing attention. In this study biodiesel was produced by transesterification process using non-edible neem seed oil as the feedstock with potassium hydroxide (KOH) and methanol as catalyst and alcohol respectively. The oil was extracted using solvent extraction process. The free fatty acid content of the refined oil was 8.42mg/KOH which corresponds to FFA value of 4.21%. The FFA was further reduced to less than 1% using two step acid esterification process. The physicochemical properties of the biodiesel was determined and compared to ASTM standards. Cetane number of the biodiesel was also estimated from its fatty acid compositions to be 53.8. The effects of methanol to oil molar ratio, catalyst weight and reaction time on kinematic viscosity were also investigated. The effect of process parameters on the yield of biodiesel was studied and the optimal yield was found to be 94% at 7:1, 1%wt, 55oC, 350rpm and 60minutes for alcohol to oil mole ratio, catalyst, temperature, speed and reaction time respectively. RSM was used to optimize the yield and a yield of 95.5% was obtained at 6:1, 1%, 55oC and 70mins for alcohol to oil mole ratio, catalyst, temperature and reaction time respectively. The effect of temperature on fuel properties (specific gravity, density, viscosity and kinematic viscosity) of the biodiesel and biodiesel-diesel blends was also studied. It was found that these properties decrease as the temperature increases and increase as the biodiesel fraction in blends increases. Empirical correlation using linear and polynomial curve fitting was used to model the fuel properties as a function of temperature and biodiesel fraction using Polymath Software. Density was well fitted by the linear model with average ADD and MAD values of 0.056% and 0.120% respectively while viscosity was best fitted by polynomial model with average ADD and MAD values of 0.83% and 3.19% respectively. The kinematic viscosity of biodiesel is affected by process parameters such as methanol to oil molar ratio, catalyst weight and reaction time and decreases to some extent as these parameters increases. Reaction time was varied with yield at different temperatures and kinetic study based on the experimental data obtained showed that the data best conform to pseudo-second order kinetic model. The reaction rate constants were within 0.00231 – 0.00856dm3/mol.mins.

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