Abstract

The environmental concern associated with the use of mineral oil based lubricants has necessitated the search for biodegradable lubricants. Currently, vegetable oils are considered to be alternatives to mineral oils for lubricant base oils due to certain inherent technical properties and their ability to be biodegradable. Whereas, research on biolubricants has advanced, very little has been done on the biodegradability of vegetable oil based lubricants especially on the impact on bioldegradability of the modification processes used for development of biolubricants. The synthesis of biolubricants from jatropha and castor oils using TMP polyol and evaluation of their biodegradability as compared to commercially available mineral oil based lubricant SAE 20/W50 was successfully carried out. The non-edible vegetable oils and lubricants were inoculated with the Bacillus sp. CDB-08 bacterial isolated from petroleum contaminated soil and their biodegradability over 28 days at an interval of 7 days was determined using gravimetric and visible ultraviolet spectroscopy methods. The jatropha oil, castor oil, jatropha TMP ester biolubricant, castor TMP ester biolubricant and mineral oil based lubricant after 28 days had 81.48 %, 96.6 %, 81.4 %, 81.4 % and 35.2 % biodegrability respectively. The jatropha oil biodegraded at the rate of 2.345 % per day and had a half-life of 22.2 days. The castor oil biodegraded at the rate of 3.1 % per day and had a half-life of 11.2 days. The jatropha TMP ester biolubricant biodegraded at the rate of 2.7 % per day and had a half-life of 22.5 days. The castor TMP biolubricant biodegraded at the rate of 2.6 % per day and had a half-life of 23.9 days. The mineral oil based lubricant biodegraded at the rate of 1.2 % per day and had a half-life of 40 days. The jatropha and castor oils as well as their synthesised TMP biolubricants are highly biodegradable while the mineral oil based lubricant is not readily biodegradable. The transesterification of jatropha and castor oils with TMP polyol has negligeable effects on their biodegradability.