Membrane crystallization for resource recovery from brine towards sustainability and circular economy

The need of achieving sustainable resource recovery, particularly in relation to critical metals extracted from brine, is a key focus in the development of a circular economy. This study underlines the significance of such recovery processes, with a special focus on lithium (Li) - a vital element in modern industry. An assessment of Li concentrations across distinct brine sources establishes the background for its recovery. The conventional method of extracting resources through evaporation ponds is thoroughly evaluated, emphasizing its limitations including prolonged operational durations, dependence on climate conditions, reliance on chemicals, challenges related to water constraint, and significant carbon emissions. In contrast, the Membrane Crystallization (MCr) process is described as a possible alternative. The research dives into the concepts of MCr, its configurations, and contrasts its operational range versus other membrane processes such as reverse osmosis (RO), forward osmosis (FO), and capacitive deionization (MCDI) processes. Advantages and market potential of MCr are introduced against its limitations. Progress in MCr process development (e.g., LiCl recovery, Li2CO3 recovery, etc.) and membrane developments (e.g., multi-layer nanofiber and 3D printed membranes) are explored. The paper finishes by outlining future research directions for MCr, emphasizing its contribution to the advancement of sustainable resource recovery strategies.