One-step hydrothermal synthesis of magnetic rice straw for effective lipase immobilization and its application in esterification reaction.

Immobilization of industrially important enzymes on supports is important to decrease the cost of the overall enzymatic production procedure. Herein, a novel method for synthesizing a new support, magnetic rice straw (MRS) in one step is reported: rice straw (RS) was soaked with Fe2+ ions and these were further reduced to form embedded Fe2O3 nanoparticles on the RS surface, forming MRS. This material presented a magnetic saturation value of 27.32 emu g-1. Lipase immobilization on MRS resulted in 94.3% immobilization efficiency and 91.3 mg g-1 of enzyme loading, which are higher than immobilization on native RS. The lipase stability was increased approximately 8-fold at 70 °C. The lipase-MRS composite was tested in the esterification reaction of biodiesel production, where it showed prominent reusability. Therefore, this novel and rapid synthesis method can provide ecological and economic support for enzyme immobilization and industrially important product formation.