Review of works in biodiesel production showed that performance of transesterification reaction has always been assessed with wrong notion of product yield. Various researchers defined yield in variety of conflicting ways. This paper addresses the existing confusion in using product yield as reaction performance criterion in biodiesel production. With reference to fundamentals of chemistry and chemical engineering, expression for fatty acid alkyl ester (FAAE) yield in transesterification was derived. The new model was used in comparison with the existing ones, to investigate the effect of transesterification reaction time via homogeneous and heterogeneous base catalyses of beef tallow. Firstly, the physicochemical properties of beef tallow were examined to determine its requirement for esterification pretreatment before the transesterification process. Calcium oxide was derived from eggshell and characterized as catalyst for biodiesel production from beef tallow. Biodiesel was produced at different reaction times and FAAE yield was calculated with all models. By comparison, new yield model gave the least results, with maximum FAAE yields of 94.2% and 87.5% recorded using homogeneous and heterogeneous catalyses respectively. Moreover, heterogeneous catalysis required much reaction time of 4 h to achieve this maximum yield compared to 1 h for homogeneous catalysis. Resolution of some notable limitations of the old models was proved possible using the new one. Yield should be explicitly defined and reported to aid result comparison and design choices in biodiesel production.

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Due to the quest to meet a basic need – food, vast potentials of numerous African crops have remained unexplored. Cucumeropsis mannii, an invaluable West African melon, is cultivated for its edible proteinous oil-rich seeds. Here, we report for the first time, its potential use for biodiesel production over an uncommon heterogeneous nanocatalyst, and for wastewater treatment. An identification of the untapped species’ seed was made, for disambiguation. Oil (CMO) was expressed from the C. mannii seeds (CMS) and characterized. The CMS was found composed of 53.5% lipids, while 46.1% of the full-fat CMS flour was recovered as vegetable oil. Transesterification experiments were performed using a specially-prepared heterogeneous nanocatalyst derived from Eobania vermiculata shells, by varying successively: methanol/oil ratio, temperature, and reaction time. Maximum biodiesel (CMOME) yield of 86.2% was achieved at catalyst concentration of 5.4%, methanol to oil molar ratio of 9:1, reaction temperature of 60 °C, after 3 h of reaction. Furthermore, part of the polyunsaturated CMO was sulphur-functionalized and utilized at different dosage levels for extraction of Ag+ from 600 to 1500 ppm simulated water. The modified CMO exhibited desirable sorption properties – sinking 100% of Ag+ from 900 ppm water, after 7-h-phase-contact at 6.9 g (20 mL)− 1 dosage. Stagewise operation (multi-staging) was found capable of improving the extraction efficiency in highly concentrated wastewater. Although CMOME conformed to EN-14214 and ASTM D-6751 standards, it had low oxidation stability; making wastewater treatment a more faithful application. Regarding the crop’s food value, residual CMS cake remained edible, even with longer shelf-life (relative to the full-fat flour) – encouraging commercial flour-defattening and consequent availability of CMO for industrial applications. Lastly, it was concluded (with some relevant recommendations) that CMO has great potentials for use as biodiesel feedstock and as heavy metal removal agent.

Carbon is a unique chemical element whose different forms or allotropes are inexhaustible in number. It has been in use since antiquity and now, the possibility of manipulating the lattice structure of its crystalline allotropes, offers it unlimited advanced applications. This review aims at demonstrating certain aspects of engineering material in different applications. Various structures of some identified allotropes carbon, respective properties and uses of the allotropes were reviewed. Amorphous carbon materials find application mainly as fuels and sometimes as parent materials for synthesis of more useful chemicals. Their limited application was ascribed to their unstable irregular patterned structure which cannot be manipulated easily to meet further needs. Structurally, carbon exists in the sp3 and sp2 hybridized state in the crystal lattice of its crystalline allotropes. Due to the salient features of its allotropes, carbon finds application in energy generation and storage, optics, electronics, opto-electronics, electro-catalysis, corrosion control, bio-sensing (diagnostics), sensing, agriculture, water treatment, making of composite materials with unique properties and more. There is no limit to the application of carbon. It was recommended that renewable and sustainable alternative precursors for synthesis of carbon nanomaterials with crystal growth control be sought for.