Li extraction from model brine via electrocoagulation: Processing, kinetics, and mechanism

Abstract

In this study, the electrocoagulation (EC) approach with the Al electrode was introduced for Li+ recovery from artificial brine. The effects of several influence factors on the EC performance as for recovery efficiency and energy consumption were systematically investigated, such as solution conductivity, electrode spacing, current density, solution pH, and initial Li+ concentration. It is demonstrated that Li+ recovery efficiency increased with the growth of current density and reaction time. Moreover, appropriate current and density could be favored to achieve efficient and economical treatment by compromising recovery efficiency and energy consumption. The results showed that more than 95% of lithium ions (1000 mg/L) could be recovered with a relatively low energy consumption of 0.064 kWh/g Li, under operating conditions of 76.9 mA/cm2 of current density, 6.45 of pH, and reaction time of 150 min. Additionally, a kinetic study was used to analyze Li+ recovery at various current densities and initial concentrations. The relevant recovery mechanism was studied using XRD, XPS, FT-IR, and SEM-EDS to analyze the precipitates generated from different initial concentrations (0, 600, 1000, and 1500 mg/L). It was reasonably concluded that the lithium recovery from brine by electrocoagulation was mainly attributed to the chemical precipitation of aluminum hydroxide coagulants.