Separation effect of Li+, Na+, and Mg2+ with alumina–lithium LDH doped with amorphous titanium dioxide

Abstract

Alumina–lithium layered double hydroxide doped with amorphous titanium dioxide (TiO2@AlLi–LDH) was synthesized through the coprecipitation of Li+ and Al3+. The structural characteristics of TiO2@AlLi–LDH were analyzed via XRD, XPS, BET and DSC–TG. Titanium oxide anions could be inserted between layers in TiO2@AlLi–LDH, and TiO2@AlLi–LDH consists of nanoflake-sized particles. The average diameter of the particles is 231.0 nm, and the particle size distribution curve is close to the normal distribution curve. The BET surface area is 174.02 m2·g−1 after recrystallization. The Li+ adsorption process of TiO2@AlLi–LDH can be described by the pseudo–second–order model, and the adsorption capacity is 11.54 mg·g−1. The structure of TiO2@AlLi–LDH was destroyed because of the reaction between Mg2+ and CO32−. The presence of Na+ significantly reduces the Li+ adsorption ability of TiO2@AlLi–LDH without destroying the structure. The separation coefficient of Mg2+/Li+ is 4269.76 when the initial mass ratio of Mg2+/Li+ is 350.20, and the separation coefficient of Na+/Li+ is 226.20 when the initial mass ratio of Na+/Li+ is 329.40. The Li+ adsorption amount of TiO2@AlLi–LDH in Qarhan salt lake brine is 5.66 mg·g−1, suggesting potential for industrial application.