Lithium Separation from Geothermal Brine to Develop Critical Energy Resources Using High-Pressure Nanofiltration Technology: Characterization and Optimization

There is a shift from internal combustion engines to electric vehicles (EVs), with the primary goal of reducing CO₂ emissions from road transport. Battery technology is at the heart of this transition as it is vital to hybrid and fully electric vehicles' performance, affordability, and reliability. However, it is not abundant in nature. Lithium has many uses, one of which is heat transfer applications; synthesized as an alloying agent for batteries, glass, and ceramics, it therefore has a high demand on the global market. Lithium can be attained by extraction from other natural resources in igneous rocks, in the waters of mineral springs, and geothermal brine. During the research, geothermal brine was used because, from the technological point of view, geothermal brine contains higher lithium content than other resources such as seawater. The nanofiltration separation process was operated using various solutions of pH 5, 7, and 10 at high pressures. The varying pressures are 11, 13, and 15 bar. The nanofiltration method was used as the separation process. High pressure of inert nitrogen gas was used to supply the driving force to separate lithium from other ions and elements in the sample. The research results supported the selected parameters where higher pressure and pH provided more significant lithium recovery but were limited by concentration polarization. The optimal operating conditions for lithium recovery in this research were obtained at a pH of 10 under a pressure of 15 bar, with the highest lithium recovery reaching more than 75%.

Influence of indigenous mixotrophic bacteria on pyrite surface chemistry: Implications for bioflotation

Given the low-cost and eco-friendly method, biotechnology has been widely utilized in industries as an alternative for physical and chemical processes, including in the biomining process (e.g., bioflotation and biobeneficiation). However, the use of biochemical reagent, which is selective for certain minerals, has not been well studied. This research was aimed to investigate the potential use of biosurfactant-producing mixotrophic bacteria as an alternative to chemical reagents during bioflotation and biobeneficiation process. Thirteen bacterial strains were investigated for their ability to produce biosurfactants and their effects on the surface properties of pyrite minerals. Bacteria-pyrite interaction experimental results showed that pyrite surface properties became more hydrophilic in the experimental systems inoculated with bacteria adapted with pyrite for 48 h than that without bacterial adaptation to pyrite, which was evidenced by the decrease in the contact angle of pyrite minerals by up to 50%. This evidence was also confirmed by the highest emulsifying index value (51.6%) attained during the bacteria-pyrite interaction. Hence, these bacteria can potentially be applied to selective flotation as pyrite depressants.