Green frothers and modern characterization tools: Toward sustainable flotation performance

Flotation remains the most widely used method for recovering valuable minerals, particularly sulfide ores and certain non-sulfide ores such as oxides and phosphates. However, its environmental impact driven by high energy consumption, substantial water usage, and dependence on petrochemical-based reagents presents increasing sustainability challenges. In recent years, green frothers produced from renewable resources or industrial waste, including rhamnolipids, sophorolipids, plant-derived glycosides, polymer–surfactant blends, and esters, have emerged as sustainable alternatives. These frothers exhibit improved foamability, froth stability, controlled bubble size distribution, and enhanced flotation selectivity compared to conventional reagents. Advanced characterization indices, such as critical micelle concentration (CMC), froth stability index, Sauter mean bubble diameter (SMD), gas holdup, and water recovery index, are highlighted to quantify frother behavior and flotation efficiency. Computational approaches, including molecular dynamics simulations and density functional theory (DFT), provide predictive insights for rational design and performance optimization of next-generation frothers. Furthermore, challenges such as variability in water quality, cost, and industrial scalability are considered, and future research directions are proposed to accelerate the transition toward environmentally sustainable and efficient flotation practices. By integrating experimental, computational, and environmental assessment methods, this manuscript aims to provide a comprehensive framework for the development and application of green frothers in mineral processing. The novelty of this article lies in its holistic framework that connects green frother chemistry, advanced characterization metrics (e.g., CMC, SMD, water recovery index), and computational tools, thereby bridging the gap between environmental sustainability and flotation performance.