Accelerating adsorption capacity and structural stability of Li1.6Mn1.6O4-type adsorbents via synergetic effect of in-situ configured Li2MnO3 layer

Abstract

Due to the urgently increased demand for lithium resources, Li1.6Mn1.6O4-type lithium ion sieve with excellent selectivity and high theoretical adsorption capacity has attracted a surge of attentions in recent decades. However, the dissolution of manganese element largely limits its large-scale practical application. In this study, taking the excellent Li+ conductivity and structure stability into consideration, a uniform Li2MnO3 coating was in situ grown on the surface of Li1.6Mn1.6O4 to stabilize the spinel structure, thus granting the H1.6Mn1.6O4 adsorbents excellent adsorption performance. Based on different characterization and application performance results, it is believed that the in-situ formed Li2MnO3 heterostructure during roasting process not only inhibits the Jahn-Teller effect of manganese, but also dramatically promotes the adsorption and desorption rates and capacities of as-configured adsorbent. Distinctively, as-prepared Li1.6Mn1.6O4-type adsorbents with Li2MnO3 heterostructure has high adsorption capacity of 38.0 mg g−1 in 20 ppm Li+ aqueous solution. After 8 cycles, it still maintains high adsorption capacity up to around 42.7 mg/g in 300 ppm Li+ aqueous with pH 12, the calculated capacity retention rate was 91.4 %, and the Mn dissolution loss rate was only 1.6 %. After 15 dynamic cycles, the granulated Li1.6Mn1.6O4-type adsorbents has an adsorption capacity of 26.4 mg/g in oil–gas field original brines with 100 ppm Li+, which is significant and important for extracting lithium resources from low-grade brines.