Production of biodiesel from palm oil using encapsulated lipase derived from k-carrageenan

The objective of this research was to produce biodiesel using encapsulated lipase in an immobilized bioreactor. K-carrageenan was used as a matrix for encapsulating lipase PS from Burkholderia cepacia and the coextrusion technique was adopted to immobilize lipase. This study has been undertaken due to the low cost, non toxic, environmentally benign characteristics of K-carrageenan and the novelty of coextrusion technique. The physicochemical studies were conducted by using Microscope, Spectrophotometer SEM, FTIR etc. The results showed the diameter of the encapsulated lipase was in the range of 1.3-1.8mm with an average membrane thickness of 200 µm. The encapsulation efficiency was found to be 42.6 percent. The optimum stability was observed at pH 7 and at temperature 40°C. The Immobilized lipase retained 72.3 percent of its original activity after using it for 5 cycles of reuse in hydrolysis of p-NPP. Immobilized encapsulated lipase was taken in stirred tank batch immobilized bioreactor (STIBR) and packed bed bioreactor (PBBR). The studies were carried out in a batch mode of operation and various process parameters were optimized for biodiesel production. HPLC was used for analyzing the biodiesel. The optimum conditions for processing palm oil in a stirred tank immobilized bioreactor (STIBR) were 30°C, 72 h reaction time and 23.7 x g relative centrifugal force. Similarly, the optimal conditions for processing palm oil in a PBBR were 1.5ml/min and 264 h reaction time. STIBR showed conversion of up to 100 percent and the PBR has shown conversion up to 82 percent. Since the STIBR has higher conversion rate, the kinetic parameters Km and Vmax were evaluated and found to be 600 mol.m�³and 0.84 mol.m�³min�¹ respectively. The kinetic parameter values were substituted into Michaelis-Menten empirical equation and the batch time was found to be the same as experimental value of 72 h. The encapsulated lipase retained 82 percent relative conversion after 5 cycles of reuse. The economic assessment of biodiesel production using immobilized enzyme catalyst process was challenging compared to the current alkali process. The Life Cycle Analysis (LCA) studies showed that biodiesel production using immobilized enzyme catalyst has lesser impact on the environment compared to the alkali catalyst and soluble enzyme catalyst. Based on the experimentation and the results, it is concluded that biodiesel production using encapsulated lipase in an immobilized bioreactor open new vistas for the scale up studies of this technology in near future.