Biocatalytic Pickering Emulsions Stabilized by Lipase-Immobilized Carbon Nanotubes for Biodiesel Production

Abstract

Biodiesel is a promising renewable energy source that can replace fossil fuel, but its production is limited by a lack of high-efficiency catalysts for mass production and popularization. In this study, we developed a biocatalytic Pickering emulsion using multiwall carbon nanotube-immobilized Candida antarctica lipase B (CALB@PE) to produce biodiesel, with J. curcas L. seed oil and methanol as substrates. The morphology of CALB@PE was characterized in detail. A central composite design of the response surface methodology (CCD-RSM) was used to study the effects of the parameters on biodiesel yield, namely the amount of J. curcas L. seed oil (1.5 g), molar ratio of methanol to oil (1:1–7:1), CALB@PE dosage (20–140 mg), temperature (30–50 °C), and reaction time (0–24 h). The experimental responses were fitted with a quadratic polynomial equation, and the optimum reaction conditions were the methanol/oil molar ratio of 4.64:1, CALB@PE dosage of 106.87 mg, and temperature of 34.9 °C, with a reaction time of 11.06 h. A yield of 95.2%, which was basically consistent with the predicted value of 95.53%, was obtained. CALB@PE could be reused up to 10 times without a substantial loss of activity. CALB@PE exhibited better reusability than that of Novozym 435 in the process of biodiesel production.

Enzyme-Loaded Mesoporous Silica Particles with Tuning Wettability as a Pickering Catalyst for Enhancing Biocatalysis

“…One includes free enzymes located in the inner aqueous phase [12][13][14][15][16][17]. The other includes enzyme-immobilized particles anchored around droplet interfaces [18][19][20][21][22][23][24][25][26], by contrast, it enables enzymes to be recycled, maximizes the contact area between enzymes and substrates, reduces diffusion distance of substrate molecules and improves the stability of enzymes. In the above two kinds of Pickering catalysis system, the changing of the organic-aqueous phases ratio or increasing particulate emulsifiers concentration is applied to improve interfacial area to enhance the enzymatic reaction.…”

Pristine and Poly(Dimethylsiloxane) Modified Multi-Walled Carbon Nanotubes as Supports for Lipase Immobilization

“…Graphene oxide (GO), having a large surface area (2630 m 2 /g) and abundant functional groups (such as epoxide, hydroxyl, and carboxylic groups), provides a great substrate for enzyme immobilization without any surface modification or any coupling agents [ 31 ]. Nevertheless, among the various nanostructured materials that might be used as novel supports for enzyme immobilization and stabilization, CNTs are of great interest to many research centers worldwide due to their stability, high adsorption capacity, improvedretention of catalytic activity, and biocompatibility [ 32 , 33 , 34 , 35 ]. Both SWCNTs and MWCNTs have been used to immobilize enzymes [ 36 ].…”

“…Enzymes can be immobilized on the surface of MWCNTs by adsorption or covalent binding, whichresultsin enhanced catalytic performance and stability. Moreover, lipases are well-known interfacially active catalysts and exhibit their catalytic abilities at the interface between the organic phase containing hydrophobic substrates and aqueous phase, so they can be activated at the hydrophobic–hydrophilic interface [ 34 , 39 ].…”

Efficient Biodiesel Production Catalyzed by Nanobioconjugate of Lipase from Pseudomonas fluorescens

“…Several materials, such as silica, ceramics, polymer resins and magnetic nanoparticles are used as support material for lipase immobilization [24][25][26]. Carbon nanotubes are gaining attention as support material for the immobilization of biomacromolecules, exploiting their electrical, mechanical and thermal properties, and general biocompatibility [27,28]. Moreover, they have the advantage to be strongly hydrophobic, thus keeping the formed glycerol away from the catalytic site of the enzymes.…”