Approach to microalgal biodiesel production: Insight review on recent advancements and future outlook

Abstract

The environmental concerns about fossil energy and rising oil prices are regular global phenomena. In such an exigency where fossil fuel sources are dwindling, carbon‐neutral biodiesel derived from microalgae lipid seems to be an important renewable energy resource. In recent years, microalgae have become a lucrative feedstock for economically viability of commercial‐scale biofuel production owing to its high biomass growth and high oil yield compared with other crops. The screening and selection of promising microalgae strain should be based on their fatty acid profile and culture conditions. The laboratory to pilot scale culture of microalgae species requires systematic experimental designs to maximize microalgal growth using open or raceway ponds, closed photo bioreactors and hybrid systems. The pros and cons of each harvesting technique, including filtration, centrifugation, sedimentation and flocculation as well cell disruption by thermal, mechanical, chemical and biological techniques, are deliberated in details. Furthermore, the application of homogeneous, heterogeneous and enzyme catalysts in transesterification processes as well as purification technologies are emphasized to ensure high‐quality biodiesel production as per ASTM norms. Microalgae comprise a potential feedstock and biodiesel synthesis from them requires a series of complex up‐streaming and down‐stream processes which are inherently disadvantageous in technology transfer from laboratory to industrial scale. This review paper is mainly focused on microalgal cultivation, harvesting, oil extraction, biodiesel production and purification technologies, and each vital process is critically reviewed in each step. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Biomass derived sulfonated carbon catalysts: efficient catalysts for green chemistry

“…While literature studies have introduced the diversity of biomass sources used for synthesizing sulfonated biochar, the impact of this diversity on the performance of sulfonated biochar is still open for discussion. 19 This section categorizes and summarizes the biomass waste suitable for BDSCCs synthesis, offering researchers a guide for selecting appropriate biomass sources. Furthermore, a comparative analysis of the performance disparities among various BDSCCs is conducted, with a preliminary discussion on the factors contributing to these differences, including raw material properties and preparation processes, and the potential future advancements of BDSCCs is evaluated.…”

“…Furthermore, in some reaction processes, the soluble polycyclic aromatic hydrocarbon portion containing SO 3 H groups on sulfonated biochar can leach into the reaction medium, causing this phenomenon. 7,19,20 However, these deactivated acid centers can be easily regenerated by hydrolyzing ester bonds with water or treating with dilute acid, and the performance of deactivated sulfonated biochar caused by pore blockage can generally be restored by washing with water or organic solvents. 7,26,35,44 In brief, the emergence of BDSCCs provides a closed-loop solution for the conversion of certain raw materials into biodiesel, promoting the comprehensive utilization of various waste streams and reducing waste generation, aligning with green biodiesel production goals.…”

“…12,17 While Konwar et al provided a summary of the structure, active sites, surface properties, applications in catalysis, and research progress of various functionalized carbon materials containing SO 3 H groups, their discussion on BDSCCs was not extensive. 7 Other literature sources that briefly mentioned BDSCCs primarily concentrated on specific application domains like biodiesel production, [19][20][21] and organic chemical reactions, 22 among others. 15 Unfortunately, these references lacked a comprehensive overview and outlook on BDSCCs and frequently disregarded the diversity of raw materials crucial for the advancement and design of BDSCCs.…”

Advances in biomass derived low-cost carbon catalyst for biodiesel production: preparation methods, reaction conditions, and mechanisms

“…However, homogeneous catalysts have several disadvantages like non-recoverable, non-biodegradable, corrosion of instruments and recyclability. 13 These issues are easily resolved by heterogeneous catalyst. Heterogeneous catalysts are extensively investigated due to ease of separation, recyclability, non-corrosiveness of instruments and no soap formation.…”

“…Heterogeneous catalysts are extensively investigated due to ease of separation, recyclability, non-corrosiveness of instruments and no soap formation. 13,14 There are a variety of materials that may be used to make heterogeneous catalysts, such as biochar, biomass ash, waste shells, agriculture products and activated carbon. 15 Researchers from all around the world have recently been interested in biomass-derived heterogeneous catalysts.…”