Enhancement of lithium extraction from low grade brines by highly hydrophilic blend membranes using MnO2 ion sieve as adsorbents

Abstract

In this study, an MnO2 ion sieve blend membrane with high hydrophilicity was developed to strength the lithium extraction from brines instead of the traditional adsorbent granulation procedure. The membrane-type adsorbent has the advantages of high stability and high-water permeability. That do not require high pressure because adsorption modules can be easily constructed by stacking or winding membranes. Therefore, membrane-type adsorbents are suitable for large-scale applications. It was confirmed that the adsorption rate and hydrophilicity of the membrane were negatively related to the increasing PVC content, while the tensile and compressive strengths could be maximized with a blending ratio of Polyvinyl chloride (PVC) and Polyacrylonitrile (PAN) (10:1). Besides, the optimized membrane with spongy porosities demonstrated a large flux and great adsorption performance for Li+ in the Qarham Salt Lake old brine. The lithium adsorption capacity could keep at 2800 mg m−2 and the desorption rate always exceeded 85% in the multicycle adsorption-desorption experiments，which indicates the long-term stability of this membrane-type adsorbent. In addition, this work contributes to the field by deepening the understanding of preparation conditions of blend membrane from multiple perspectives. Furthermore, a strategy is proposed for designing a blending modification membrane structure using the incorporation of two or more materials, which offers potential for future advancements in membrane technology.