A systematic study of the diffusion mechanism and effect of mass transfer limitation during the adsorption of CO₂ onto polyaspartamide is presented using a differential adsorption bed method, carried out in a 100 × 60 × 40 mm packed-bed adsorption unit. The rate-limiting step where mass transfer limitation is dominant was studied using diffusion models. It was observed that intraparticle diffusion mechanism is the major contributor to the resistance offered to the transport of gas molecule through polyaspartamide. The behaviour of polyaspartamide, based on the intraparticle diffusion rate parameter derived from the plots of CO₂ adsorbed versus the square root of time, signified that the adsorption mechanism involved both film and intraparticle diffusion. The intraparticle diffusion parameter (kid) obtained was dependent on temperature as well as intraparticle convection effects and ranged from 1.24 × 10⁻⁴ to 2.13 × 10⁻⁴ ms⁻¹. The Biot number (Bi) values were all greater than 10 (ranged from 17.80 – 30.74), confirming that the intraparticle diffusion was the rate-limiting step and heat transfer is more by conduction from the gas film layer than convection within the pores of polyaspartamide. Results from this study provide an important basis for future scale-up and optimisation of CO₂ capture process using polyaspartamide.

Lacking in literature is the use of discard coal to produce activated carbon and in its subsequent use in the storage of natural gas. In this study, the characterization and gas storage evaluation of a largely porous activated carbon with large surface area synthesized from discard coal were investigated. Discard coals are waste material generated from coal beneficiation process. In developing the activated carbon, chemical activation route with the use of KOH reagent was applied. The effects of KOH/discard coal weight ratio (1:1, 2.5:1, 4:1), temperature (400–800 °C) and particle size (0.15–0.25 mm, 0.25–0.5 mm, 0.5–1 mm) on the adsorptive properties of the activated carbon were methodically evaluated and optimized using response surface methodology. The synthesized activated carbon was characterized using BET, SEM/EDS, and XRD. The results showed that for each activation process, the surface area and pore volume of the resulting activated carbon increased with increased temperature and KOH/discard coal weight ratio. The maximum surface area of 1826.41 m²/g, pore volume of 1.252 cm³/g and pore size of 2.77 nm were obtained at carbonization temperature of 800 °C and KOH/discard coal weight ratio of 4:1. Methane and nitrogen adsorption data at high pressure were fitted to Toth isotherm model with a predictive accuracy of about 99%. Adsorption parameters using the Toth model provides useful information in the design of adsorbed natural gas storage system. According to the requirements of adsorbent desired for natural gas storage, it could be stated that the synthesized activated carbon could well be applied for natural gas storage.

As part of the Kyoto Protocol, several Sub-Saharan Africa countries vowed to use more renewable energy sources, and the number of Sub-Saharan Africa countries that have undertaken renewable energy initiatives has expanded considerably over the preceding decade. However, assuring demand while reducing climate change has always been one of the most significant difficulties confronting the global energy sector. This review looks at the state of practical renewable energy interventions in Sub-Saharan Africa countries over the last decade (2010–2020), focusing on infrastructure development and accessibility, decentralization, distribution, and communal acceptance, donor funding and private sector involvement, and the role of state political influence in renewable energy strategies. This study's findings suggest that renewable energy interventions in Sub-Saharan Africa are based on mature and commercialized technologies, that natural resources for energy generation have not been fully explored, and that ongoing research and development on raw material or feedstock availability will benefit regional and national projects. The findings also show that off-grid technology interventions exist in Sub-Saharan Africa. However, the adoption of a decentralized approach to renewable energy generation, particularly in rural areas, financing, and the need for integrated project design and implementation, which includes factors such as community mobilization, social, economic, institutional, and technical engagement, have all hampered the implementation of such technologies.