Immobilization of lipase on Na-montmorillonite and modified montmorillonite: Investigation of biocatalytic activity of immobilized lipases in biodiesel production from waste cooking oil

In this paper, the immobilization of lipase from Candida rugosa on hydrophilic Na-montmorillonite (MT) and hydrophobic modified montmorillonite (MTS) is investigated. Hydrophobic MTS was prepared by changing the nature of hydrophilic MT with cetrimonium bromide surfactant. The enzymatic activity of lipase immobilized on Na-montmorillonite (LMT) and lipase immobilized on modified montmorillonite (LMTS) was investigated in the production of biodiesel from waste cooking oil. The support modification and enzyme immobilization were evaluated by BET, XRD, and SEM techniques. The effects of temperature, time, water content, and the molar ratio of methanol to oil on biodiesel yield were also investigated. The results showed that the activity of LMTS was much better than LMT. Under optimal conditions, the biodiesel yield produced by LMTS was about 86.4%. LMTS showed good storage stability, and after 30 days of storage at 4 ℃, the biodiesel yield was about 64.2%, while the biodiesel yield of free lipase (FL) was about 57.1%. In addition, LMTS had good reusability compared to LMT, and the biodiesel yield after 10 cycles was about 51.6%.