Reverse osmosis process combining energy consumption analysis and mass transfer in the concentration of lithium-enriched brine

Abstract

The recovery and utilization of water resources, as well as the concentration and extraction of high-value ions, are the merits of the reverse osmosis process in exploiting salt lake brine. Herein, we investigated the mechanism influencing the concentration performance of reverse osmosis membranes by considering energy consumption and mass transfer processes in the concentration of lithium-enriched brine. Firstly, different types of reverse osmosis membranes were applied to analyze their impact on flux and ion concentration for various solutions, with a membrane exhibiting a minimum lithium loss having a flux of 66.06 L·m⁻²·h⁻¹. Secondly, the membrane with the minimum lithium loss was selected for concentrating lithium-enriched brine. We clarified how solution properties, flow state, and recovery affect solution concentration, ion enrichment, and transmembrane transport during the concentration process. Furthermore, the relationship between ions concentration and energy consumption in the continuous concentration process of reverse osmosis was quantitatively demonstrated by two concentration processes, the enrichment ratio of Li⁺ can reach 5.53 when recovery was 80 %. Additionally, we simulated the effects of concentration processes on water flux and ion transport using mathematical expressions combined with irreversible thermodynamic model and concentration polarization model, the mean absolute percentage error was 4.38 % between experimental values and simulated values. This study further elucidates principles related to energy consumption and ion transport in reverse osmosis concentration processes while providing technical support for concentrating high-value ions in brine.