Effect of peroxide concentration on the epoxidation of vegetable seed oil

Abstract

The present study focuses on the development of a novel epoxidized vegetable oil (EKO) prepared by the insitu epoxidation of Karingotta oil (KO), a non-edible feedstock with high iodine value (119 g/100 g oil). The key parameters that affect the epoxidation reaction are temperature, time, molar ratio of DB (No. of double bonds in oil): H2O2, molar ratio of DB: CH3COOH and the amount of catalyst. The effect of molar ratio of DB:H2O2 on the epoxidation of Karingotta oil is presented here. Epoxidation was carried out at three different ratios of DB: H2O2 viz, 1:1.1 (P1.1), 1:1.5 (P 1.5) and 1:2.0 (P2.0). The determination of iodine value indicated that the double bond conversion was higher for P1.5 in comparison to P1.1 and P2.0. The increase in the concentration of peroxide from 1.5 to 2.0 did not affect the double bond conversion. Further, the oxirane value increased for P1.5 compared to P1.1 However, for P2.0, the oxirane value reduced indicating the possibility of ring opening side reaction of epoxy group at higher concentration of H2O2. FTIR spectra of all the epoxidized samples exhibited characteristic peak at 827 cm−1 confirming the formation of epoxy functionality in the oil. Quantitative estimation of epoxidation was carried out using 1H NMR which indicated 43 % epoxidation for P1.1, 54 % epoxidation for P1.5 and 43 % epoxidation for P2.0. The iodine value, oxirane value and 1H NMR spectral analysis revealed that a DB:H2O2 ratio of 1:1.5 can promote significant epoxidation of Karingotta oil which can be a potential source for epoxy prepolymers.