Review of emulsion liquid membrane for heavy metals recovery from wastewater/water: Stability, efficiency, and optimization

•Investigating ELM principles, mechanisms, components, and key indicators performance.•Reviewing ELM's efficiency in heavy metal extraction from various solutions.•Conducting a comprehensive study on parameters affecting ELM stability and efficiency.•Evaluating novel EILM and PELM techniques as stability solutions in heavy metal removal.•Highlighting the use of experiments methodology designs for ELM efficiency and stability optimization. Heavy metal ions in wastewater pose significant ecological risks, necessitating effective removal methods. This review critically examines Emulsion Liquid Membrane (ELM) technology, a forefront solution that integrates green technologies for sustainable and cost-effective heavy metal removal. ELM stands out for its environmentally friendly approach, utilizing non-toxic and biodegradable materials such as green solvents derived from vegetable and plant origin that align with green chemistry principles. We thoroughly examine ELM's core principles, mechanisms, components, and key performance metrics, focusing on its application in wastewater and aqueous solutions. We present a detailed parametric study examining factors influencing ELM's stability and efficiency. Significantly, this review assesses recent advancements in Emulsion Ionic Liquid Membrane (EILM) and Pickering Emulsion Liquid Membrane (PELM). These novel methods are evaluated as potential solutions to overcome ELM's stability challenges, and their performance in heavy metal removal is compared with traditional ELM. Additionally, this paper underscores the application of the design of experiments methodology as a strategic approach to optimize ELM's efficiency and stability, marking a critical advancement in this field. [Display omitted]