A Review on Bio-Based Catalysts (Immobilized Enzymes) Used for Biodiesel Production

Abstract

The continuous increase of the world’s population results in an increased demand for energy drastically from the industrial and domestic sectors as well. Moreover, the current public awareness regarding issues such as pollution and overuse of petroleum fuel has resulted in the development of research approaches concerning alternative renewable energy sources. Amongst the various options for renewable energies used in transportation systems, biodiesel is considered the most suitable replacement for fossil-based diesel. In what concerns the industrial application for biodiesel production, homogeneous catalysts such as sodium hydroxide, potassium hydroxide, sulfuric acid, and hydrochloric acid are usually selected, but their removal after reaction could prove to be rather complex and sometimes polluting, resulting in increases on the production costs. Therefore, there is an open field for research on new catalysts regarding biodiesel production, which can comprise heterogeneous catalysts. Apart from that, there are other alternatives to these chemical catalysts. Enzymatic catalysts have also been used in biodiesel production by employing lipases as biocatalysts. For economic reasons, and reusability and recycling, the lipases urged to be immobilized on suitable supports, thus the concept of heterogeneous biocatalysis comes in existence. Just like other heterogeneous catalytic materials, this one also presents similar issues with inefficiency and mass-transfer limitations. A solution to overcome the said limitations can be to consider the use of nanostructures to support enzyme immobilization, thus obtaining new heterogeneous biocatalysts. This review mainly focuses on the application of enzymatic catalysts as well as nano(bio)catalysts in transesterification reaction and their multiple methods of synthesis.

Chitosan-Grafted Halloysite Nanotubes-Fe3O4 Composite for Laccase-Immobilization and Sulfamethoxazole-Degradation

“…Biocatalyst enzymes have long been explored, due to their high specificity, catalytic power, and stereo-selectivity [ 2 ]. Enzyme immobilization processes gave us bio-based catalysts with enhanced properties for diverse applications [ 3 , 4 ]. Laccase is a capable biocatalyst for micro-pollutant removal [ 5 ].…”

Aqueous enzymatic extraction of palm kernel oil

“…One factor for reducing production cost in enzymatic method is reusing the enzyme (Santos et al 2020). To assess the reusability of the enzymes contained in a digestive drug, the incubation was set based on the condition giving the highest oil yield which is ratio palm kernel to water of 1:5, weight of digestive drug of 9% w/w, pH of 9, incubation time of 90 min at 45C.…”

“…An immobilization enzyme for the AEE process has been developed to overcome the cost issue. The main advantage of using an immobilized enzyme is the possibility of using it several times without losing its activity (Wan et al 2008;Santos et al 2020). Long et al have successfully immobilized a mixture of cellulase, pectinase and hemicellulase onto alginateglutaraldehyde matrix to hydrolyze cell walls of flaxseed.…”

Influence of the Procedure to Immobilize Lipase on SBA-15 for Biodiesel Production from Palm Kernel Oil

“…In order to ensure a catalytically active lipase conformation in organic media, the enzyme molecule must have a defined hydration layer, separating the solvent from contact with the surface of the protein and contributing to the increase of its internal flexibility [12]. A way to protect the native configuration of the enzyme is through its immobilization, i.e., confinement of the biocatalyst on solid supports [13][14][15]. The selection of the immobilization method should be based on certain parameters, such as global activity of the immobilized derivative, regeneration and inactivation characteristics, cost of the immobilization procedure, toxicity of the immobilization reagents and desired final properties of the immobilized enzyme [13].…”

“…Several materials have been tested for lipase immobilization [16,17]. However, comparative studies show significant differences in the performance of immobilized lipases in different substrates and show that the immobilization of lipases is still a complex challenge, since the extent of immobilization depends on the structure of the enzyme, on the immobilization method and on the type of support [14].…”