To reduce fossil fuel dependence and greenhouse gases, biomass energy is in high demand. Hura crepitans (HC) is a widely distributed plant species in Benin. But its seed oils are reputed to be purgative and unfit for consumption. So, we collected the seeds of HC in Agame (South of Benin). They were extracted and the seed oils have been converted into biodiesel. First, the quality indices (acid, peroxide, iodine and saponification) were determined. Then, elementary physicochemical parameters and fuel properties of the extracted oil have been highlighted according to standardised methods. Transesterification parameters of the seed oils (alcohol/oil and catalyst/oil ratios, temperature and yield) were also studied. The fatty acids of vegetable oil and the characteristics of its obtained biodiesel were finally identified. It appears that HC seeds have a lipid potential of 52.54%. Its oil is unsaturated and dominated by linoleic acid (54.13%). The yield of the transesterification reaction is 81.47%. The fuel parameters of the obtained biodiesel are: acidity (0.41%); density at 26°C (0.887); cetane number (54.44) compared to those of HC seed oils: acidity (4.81%), density at 26°C (0.929) and cetane number (44.53). The biodiesel obtained by transesterification with potash has much better parameters that comply with biodiesel standards. These results suggest that biodiesel of HC could be proposed to power Diesel engines without a preheating system.

Natural minerals are a powerful tool in politics when some have a major role in production. Its depletion is now a hot topic worldwide. Thus, the safety of the environment, natural surface water, groundwater and the protection of soils from chronic contamination by metallic and inorganic elements is a global concern. Indeed, industrialization and development have led to the generation of huge and varied amounts of waste, including electronic waste (e-waste), which is released into the environment. Although e-waste is classified as hazardous, most of it is not recycled and developed countries with strict environmental protection legislation send most of their e-waste to developing countries where regulations are lax. These electronic devices and components after being used are simply dumped into the environment due to lack of treatment and recycling strategy. As a result, they become a threat to the environment, ecosystems and humans. African countries are among the most vulnerable nations. But they are unfortunately ignored and underestimated. To date, there is no e-waste recycling unit (factory) in most African countries and mainly in the Republic of Benin. In response to this challenge, this study explored the different techniques used for the recycling of waste electrical/electronic equipment in order to develop a new environmentally friendly approach in future work, for the extraction and recycling of the usual and valuable metallic elements contained in electronic waste (printed circuit boards) released into the environment. For this purpose, a bibliographic research was carried out from 20 April to 16 October 2021. The results obtained allowed us to identify the advantages and disadvantages of existing recycling methods.