Kinetics and hydrodynamics of Candida antartica lipase-catalyzed synthesis of glycerol dioleate (GDO) in a continuous flow packed-bed millireactor

• Nurul Nadiah Abd Razak^a,b
• Patrick Cognet^b
• Yolande Pérès^b
• Lai Ti Gew^a,e

• ^aDepartment of Biological Sciences, School of Medical and Life Sciences, Sunway University, Petaling Jaya, Selangor, 47500, Malaysia
• ^bLaboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, 31423, France
• ^cCentre for Carbon Dioxide Capture and Utilization (CCDCU), School of Engineering and Technology, Sunway University, Petaling Jaya, Selangor, 47500, Malaysia
• ^dDepartment of Engineering, Lancaster University, Lancaster, LA1 4YW, United Kingdom
• ^eSunway Materials Smart Science & Engineering (SMS2E) Cluster, Sunway University, Petaling Jaya, Selangor, 47500, Malaysia

Diacylglycerols (DAG) have been widely used in many industries due to their remarkable capabilities as emulsifiers and stabilisers. However, developing a sustainable and an effective synthesis method for DAG remains a challenge. Continuous flow bio-reactor is recognized to be more productive, controllable, and reliable instrument for developing green and intensified processes. In this work, a continuous flow packed bed millireactor was employed for the synthesis of glycerol dioelate (GDO) catalyzed by immobilized lipase namely Candida antartica. Experiments were carried out to evaluate the kinetic parameters as well as to assess the internal and external mass transfer limitations. Using one-factor-at-a-time variables method, maximum oleic acid conversion and GDO selectivity were achieved at 85% and 74% respectively, at 0.15 g of lipase, 77 min of residence time with 1.6:1 molar ratio of oleic acid/glycerol. Hydrodynamic studies showed that the esterification reaction is kinetically controlled and unaffected by external and internal mass transfer. Employing Lilly–Hornby model for kinetic evaluation, Km values increased with increasing flow rates, whereas, Vmax appeared to be flow rate independent. Reusability tests revealed that the activity of immobilized lipase remained the same after 9 successive reaction cycles. At 11 days of operation, the stability of the lipase in the continuous packed bed millireactor decreased only 5–7%, indicating satisfying operational results and recyclability. This work may promote the enzymatic engineering synthesis of DAG, facilitating the creation of a cleaner and safer process. It has the potential to broaden the application of enzymes in continuous flow micro or millireactors.

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