Abstract:
e diminishing reserves and environmental consequences of the fossil fuel-based petrodiesel necessitate the exploration of an
alternative fuel with better quality and minimum environmental impacts. e study explores the optimization of biodiesel
production from nonfood and locally available mixed feedstocks as an e ective and a sustainable approach to solve the in su ciency and high costs of single oil feedstock. e selection of suitable oil feedstocks and optimization of process variables are
the prime issues for cost-e ective industrial scale production of biodiesel from mixed feedstocks toward the industrial scale
production of biodiesel. e objective of this study was to optimize process variables for the alkaline transesteri cation of mixed
castor seed and microalgae oils to optimize the yield of biodiesel. Oils were extracted from dried microalgae (Chlorella vulgaris)
biomass and castor seed kernel using methanol. e oils were puri ed, characterized, mixed in a 1 :1 ratio, and converted to
biodiesel. e transesteri cation experiments designed according to the central composite design (CCD) were used to optimize
the yield of biodiesel through the response surface methodology (RSM). Experimental results were analyzed by response surface
regression to produce a model for predicting biodiesel yield. Model signi cance, tness, the e ect of signi cant variables, and
interactions between the variables on the yield of biodiesel were studied through the analysis of variance (ANOVA). e
optimization of transesteri cation process variables revealed that the catalyst concentration of 1.23% (w/w), ethanol to mixed oil
ratio of 5.94 :1 (v/v), and reaction temperature of 51.0°C were the optimum conditions to achieve an optimum biodiesel yield of
92.88%. Validation experiments conducted under the optimum conditions resulted in the biodiesel yield of 92.36%, which is very
close to the model predicted value. Various standard methods were used to characterize the biodiesel produced under optimum
conditions, and it was found compatible with ASTM 751 and EN14214 biodiesel standards
