Recovery of Li⁺ from oilfield produced water using La₂O₃-coated lithium ion-sieves

Abstract

With the rising demand for power batteries in recent years, the search for alternative lithium resources has become a key research focus. Oilfield produced water is a type of lithium-containing wastewater generated during oil extraction processes, offering significant potential for resource recycling. However, conventional lithium recovery methods, such as solvent extraction and electrochemical techniques, exhibit low efficiency due to the presence of organic substances (e.g., grease, ammonia nitrogen, COD) and inorganic contaminants (e.g., heavy metals, salts). To enhance lithium recovery efficiency from oilfield wastewater, this study synthesized lithium manganese oxide (Li₁.₆Mn₁.₆O₄) via a soft chemical method using various lithium and manganese sources, followed by surface modification with lanthanum oxide (La₂O₃). The La₂O₃-modified material was applied for cyclic adsorption and recovery of Li⁺ from oilfield produced water. Experimental results indicate that combining MnCO₃ and LiOH as manganese and lithium sources in a 1:1 ratio produces the Li₁.₆Mn₁.₆O₄ precursor with optimal adsorption capacity and minimal manganese loss. Through multiple adsorption-desorption cycles using both simulated and actual oilfield produced water samples from various locations, it was demonstrated that the inherent chemical inertness of La₂O₃ coating on Li₁.₆Mn₁.₆O₄ effectively mitigates manganese dissolution. La₂O₃ coating effectively mitigates manganese loss from Li₁.₆Mn₁.₆O₄. After 10 cycles, the manganese loss rate remained below 1.5 %, with the adsorption capacity sustained at 25 mg·g⁻¹ . This study offers a novel pathway for lithium recovery from oilfield produced wastewater.