Exploring the Impact of Alcohol Type on the Yield of Biodiesel from Cottonseed Oil Using NaOH Catalyst and Response Surface Methodology Statistical Tools

A study on the impact of alcohol type on the yield of biodiesel from cottonseed oil oil was conducted by carrying out transesterification of cottonseed oil with three different alcohols (methanol, ethanol and butanol) in presence of sodium hydroxide (NaOH) as catalyst. Response Surface Methodology based on Central Composite Design was used to optimize the process and analysis of variance (ANOVA) used for conducting the relevant statistical analysis. Quadratic models were developed to predict biodiesel yield as a function of the transesterification process variables – alcohol/oil molar ratio, catalyst concentration, reaction temperature, reaction time, and agitation rate. The statistical tool made predictions on biodiesel yield from the processes as follows, methanol, 83.25% ethanol, 84.36% and butanol, 74.59 % at the optimal condition for methanol process as methanol/oil molar ratio 6:1, temperature 55oC, time 45 mins, catalyst concentration 1%, and rate of mixing 300rpm. Ethanol/oil molar ratio18:1. temperature 45oC, time 45 mins, catalyst concentration 1%, and rate of mixing speed, 300rpm. Butanol/oil molar ratio 19:1, temperature 40oC, time 15mins, catalyst concentration 0.5%, and mixing speed 300rpm, The optimized conditions were validated with the actual biodiesel yield of 82.5% for methanol, 85% for ethanol and 75% for butanol. Experiments were conducted to validate the predicted optimal conditions presented actual biodiesel yield of 82.5% for methanol, 85% for ethanol and 75% for butanol. The error between the experimental and predicted yield was found to be is less than 0.6%, showing that the model correctly explains the influence of the process variables on the production of alkyl ester from cotton seed oi and have sufficient accurancy to predict the amount of alkyl ester yield and therefore it can be concluded that the generated models have sufficient accurancy to predict the amount of alkyl ester yield.