Publisher: Chemical Society of Nigeria

Preparation and Characterisation of Dehydrated Castor Oil (DCO) By Infra Red Spectroscopy and Titrimetric Methods

M. B. Dalen, A. Q. Ibrahim, H. M Adamu, A. I. Ikeuba
KEYWORDS: dehydration, hydroxyl value, iodine value, spectral analysis, titration, stretching vibration

ABSTRACT:

Mechanically extracted Castor Oil (CO) was characterized for its physicochemical properties using conventional methods. The results showed refractive index (1.415), relative viscosity (5.6), pH (6.5), specific gravity (0.962), acid value (3.83mgKOH/g), hydroxyl value (160.35mgKOH/g of oil) and iodine value (83.44g I2/100g of oil) which are within ASTM values. The IR spectral analysis of the oil showed characteristic absorption bands for hydrogen bonded   OH (V) at 3450 cm-1 with  sharp bands of CH (V) at 3010cm-1, C=O(V) for carboxylic acids at 1750 cm-1 and olefinic  C=C(V) at 1680 cm-1 antisymetric stretching vibration.  Acid catalysed dehydration of the oil was monitored by measurements of changes in hydroxyl values and IR spectral analysis with time. The results showed that hydroxyl value decreases from160.35mg KOH/g at 0 mins to 38.75mg KOH/g at 90 mins while spectral analysis showed a decrease in OH absorbance from 0.8686 to 0.2132 and an increase in double bond absorbance from 0.3233 to 0.5528. Furthermore, Dehydrated Castor Oil (DCO) was characterized titrimetrically and the following results were obtained; refractive index (1.465), relative viscosity (4.39), pH (2.0), specific gravity (0.952), acid value (8.23mg KOH/g of oil), hydroxyl value (36.17mg KOH/g of oil) and iodine value (130.92g I2/100g of oil). Similarly, IR spectral analysis lays claims to the formation of DCO. Therefore, monitoring and evaluation of dehydration parameters by titrimetric methods and infrared spectroscopy gave effective and complimentary results


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