The
biodiesel obtained from nonedible and waste-cooking oils through
the transesterification process has been recognized as a renewable
energy source. This transesterification process produces glycerol
as the main byproduct. Glycerol and its derivatives have a lot of
applications in the pharmaceutical industry, organic synthesis, and
the cosmetic industry. The glycerol can be converted into value-added
derivatives via several catalyzed chemical reactions, viz. esterification,
selective reduction, selective oxidation, pyrolysis, halogenation,
condensation, carboxylation, dehydration, reformation, transesterification,
etherification, etc. Among various glycerol derivatives, glycerol
carbonate is one of the most value-added products which is employed
in industrial application for the preparation of polyurethanes. There
are several methods for its preparation using glycerol as a platform
molecule, but the transesterification method using dimethyl carbonate
is the most efficient way employing mild reaction conditions and the
least harmful reagents. This review presents a critical assessment
of the available published information on large scale production of
glycerol carbonate using various homogeneous and heterogeneous catalysts
reported in the last five years. Effects of relevant reaction parameters
affecting the transesterification route have been discussed with some
suggestions for future work in this area.
We report a facile method to produce composites of hierarchically porous graphene-based materials embedded with onion-like carbons (Gr-OLCs) for high power density supercapacitors. Gr-OLCs were produced from the mixture of glucose, thiourea, and ammonium chloride, through the condensation reaction and subsequent blow into three-dimensional (3D) structure, and carbonization process. Owing to its high surface area, hierarchical pore distribution, and interconnected carbon networks embedded with onion-like carbons, this carbon exhibited the specific capacitance of 140 F g-1 at a high current density of 64 A g-1. Highly porous and interconnected carbon structure tend to facilitate the movement of electrolyte ions within the electrode and provide an efficient pathway for the movement of charge carriers, resulting in an exceptionally high power density of 1,737 kW kg-1, while maintaining its high energy density of 30 Wh kg-1 at current density of 256 A g-1. Studies on the complex capacitance of the cell revealed that these carbon electrodes possess stable energy storage features with minimal capacitive loss, achieving both high power and energy densities. This work may provide a new type of carbon-based electrode materials which can meet the requirements for high power energy storage devices.
A low-cost and high-purity calcium oxide (CaO) was prepared from waste crab shells, which were extracted from the dead crabs, was used as an efficient solid base catalyst in the synthesis of biodiesel. Raw fish oil was extracted from waste parts of fish through mechanical expeller followed by solvent extraction. Physical as well as chemical properties of raw fish oil were studied, and its free fatty acid composition was analyzed with GC-MS. Stable and high-purity CaO was obtained when the material was calcined at 800 °C for 4 h. Prepared catalyst was characterized by XRD, FT-IR, and TGA/DTA. The surface structure of the catalyst was analyzed with SEM, and elemental composition was determined by EDX spectra. Esterification followed by transesterification reactions were conducted for the synthesis of biodiesel. The effect of cosolvent on biodiesel yield was studied in each experiment using different solvents such as toluene, diethyl ether, hexane, tetrahydrofuran, and acetone. High-quality and pure biodiesel was synthesized and characterized by H NMR and FT-IR. Biodiesel yield was affected by parameters such as reaction temperature, reaction time, molar ratio (methanol:oil), and catalyst loading. Properties of synthesized biodiesel such as density, kinematic viscosity, and cloud point were determined according to ASTM standards. Reusability of prepared CaO catalyst was checked, and the catalyst was found to be stable up to five runs without significant loss of catalytic activity.
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