SYNTHESIS AND EVALUATION OF SURFACTANT AND BIODIESEL FROM SESAME OIL

Abstract

The search for alternative biodegradable and sustainable raw materials from renewable sources for industrial chemicals to replace the depleted commercially available petrochemicals raw materials has become an area of great research interest. Triglycerides obtained from oil seed crops such as sesame are key potential raw materials for the energy and chemical industry using renewable resources. The objective of this work was to extract oil from sesame seeds, and use it to synthesise biodegradable biodiesel and surfactant. The extracted sesame oil was trans-esterified to SEFAMEs biodiesel, then sulphonated using chlorosulphonic acid and neutralized by sodium hydrogen carbonate to form the anionic sodium sesame fatty methyl ester sulphonate (SEFAMESO) surfactant. The structures of Sesame oil, SEFAMEs biodiesel and the SEFAMESO surfactant were characterized by elemental, HPLC-MS, 1H-NMR, 13CNMR and FT-IR spectroscopic studies. The peaks at 1418 to 1376 cm-1 and a singlet at 3.647 ppm in the SEFAMEs biodiesel FT-IR and 1H-NMR spectra, respectively, corresponded to methyl ester group (-O-CH3); which confirmed successful transesterification of sesame oil to biodiesel. Whereas, the intense peak at 1419 cm-1 and 4.690 ppm in the SEFAMESO surfactant FT-IR and 1H-NMR spectra, respectively, corresponded to sulphonate group (S=O), thus, confirmed the presence of sulphonate esters group. The obtained fuel properties of SEFAMEs biodiesel were; density of 840 kg/m3, flash point of 160 oC, kinematic viscosity of 3.6 mm2/s, pour point of -8 oC and calorific value of 3950 kJ/kg. These values compared well with those of commercially available diesel and it can be used in the existing diesel engine without modification. The evaluated SEFAMESO surfactant solution properties were Krafft temperature, foam-ability and micellar properties. The obtained Krafft point was 19.75 ᵒC and foamstability was 54.48 %. Conductivity and viscosity as functions of the SEFAMESO surfactant concentration in aqueous solution at temperature of 298.15, 303.15, 313.15 and 323.15 K were used to determine micellar properties: the critical micelle concentration (CMC) values, thermodynamic parameters of micellization and ionisation degree of micellization of the surfactant. The CMC value was 1.435 x10-4 mol/L, change in free energy of micellization -53.78 kJ/mol, and the counter-ion binding degree 0.687 at 298.15 K. The solution properties of SEFAMESO surfactant were good and showed that the synthesized surfactant could be applied as a cleansing agent. This work showed that sesame oil is a potential and viable feedstock for industrial chemicals which can supplement or replace non-biodegradable petroleum based diesel and surfactants in some applications.