Modeling Co toxicity effects on Acidithiobacillus ferrooxidans for environmentally sustainable recycling of...

The rapid expansion of lithium-ion battery (LIB) production, driven by the rise of electric vehicles and renewable energy storage, has led to growing concerns about end-of-life management and critical material recovery. In this context, biotechnological processes represent an environmentally sustainable alternative to conventional recycling methods such as pyrometallurgy and hydrometallurgy, offering reduced impacts on both ecosystems and human health. However, the performance of bioleaching systems depends heavily on microbial tolerance to toxic metals released from LIBs. This study focuses on assessing the toxicological effects of Co, a key strategic metal in LIBs, on Acidithiobacillus ferrooxidans, a model organism for bioleaching applications. Experimental findings reveal that Co exhibits greater toxicity than Cu, Cd, Ni, Zn, and As, but is less toxic than Cr. Co concentrations exceeding 5 g/L result in a 260% increase in Fe²⁺ oxidation time and an 80% reduction in the Fe oxidation rate. Additionally, elevated Co levels significantly prolong the exponential growth phase, indicating metabolic stress. A predictive mathematical model was developed and validated to describe bacterial growth and Fe²⁺ oxidation under varying Co concentrations, achieving a determination coefficient (R²) above 0.95. This model serves as a practical tool for optimizing process parameters in the bio-recycling of LIBs, enabling more efficient and scalable engineering applications. These findings contribute to the advancement of greener technologies for critical raw material recovery and support the integration of bio-based methods into circular economy strategies for battery waste management.