The inception of sustainable and cleaner extraction technology has paved the way for the innovative development of nonconventional extractions, such as supercritical fluid extraction, apart from conventional extraction counterparts. The concept of biomass waste-to-wealth for the conversion of biomass waste or by-products into value-added products for diversified applications had piqued the prominent interest of researchers and industry players, especially with the abundance of biomass resources readily available in tropical regions that have yet to be tapped into to reach their full potential. In this paper, a critical review of the developments of supercritical fluid technology from its initial inception up to commercialized scalability, including its limitations, extraction of potential tropical biomass wastes for various types of applications, such as biopesticides, bio-repellents, phenolics, and lipids for biofuel, and its role in circular bioeconomy and sustainable development approaches, are discussed in detail.

An experimental investigation has been carried out to investigate the rheological effect of hydrogenated oil-based drilling fluid when dispersed with graphene nano-sheets. The rheological aspects that were investigated were viscosity and shear stress of the fluid respectively. The weight concentration of graphene sheets carried out in this experimental investigation were 25 ppm, 50 ppm and 100 ppm respectively. Graphene nano-sheets were dispersed via hydrodynamic cavitation dispersion and ultrasonic bath for three (3) hours each. From the analysis, the graphene-oil based drilling fluid exhibit higher viscosity as compared to the hydrogenated oil-based drilling fluid over the shear rate range of 0 – 140 s-1. Interestingly, the graphene-oil based fluid is a Bingham fluid but behaves similar to a Newtonian fluid as it possesses zero shear stress. Temperature dependence of the studied nanofluid was carried out at 30̊C, 40̊C and 50̊C respectively to observe the relationship between the additions of nanoparticles into the hydrogenated oil-based drilling fluid as compared to the base fluid. Two rheological models (Bingham model and Power Law model) were fitted to predict the behavior of graphene-oil based drilling fluid with respect to temperature and shear rate