Application and Analysis of Bipolar Membrane Electrodialysis for LiOH Production at High Electrolyte Concentrations: Current Scope and Challenges

Abstract

The objective of this work was to evaluate obtaining LiOH directly from brines with high LiCl concentrations using bipolar membrane electrodialysis by the analysis of Li+ ion transport phenomena. For this purpose, Neosepta BP and Fumasep FBM bipolar membranes were characterized by linear sweep voltammetry, and the Li+ transport number in cation-exchange membranes was determined. In addition, a laboratory-scale reactor was designed, constructed, and tested to develop experimental LiOH production tests. The selected LiCl concentration range, based on productive process concentrations for Salar de Atacama (Chile), was between 14 and 34 wt%. Concentration and current density effects on LiOH production, current efficiency, and specific electricity consumption were evaluated. The highest current efficiency obtained was 0.77 at initial concentrations of LiOH 0.5 wt% and LiCl 14 wt%. On the other hand, a concentrated LiOH solution (between 3.34 wt% and 4.35 wt%, with a solution purity between 96.0% and 95.4%, respectively) was obtained. The results of this work show the feasibility of LiOH production from concentrated brines by means of bipolar membrane electrodialysis, bringing the implementation of this technology closer to LiOH production on a larger scale. Moreover, being an electrochemical process, this could be driven by Solar PV, taking advantage of the high solar radiation conditions in the Atacama Desert in Chile.

Modeling and Validation of a LiOH Production Process by Bipolar Membrane Electrodialysis from Concentrated LiCl

“…Electrical resistance value in the bipolar membrane ( ) is obtained from Equation (21), determined empirically as a function of applied current density ( ) in A/m 2 and effective membrane area ( ) in m 2 . This equation has been determined from experimental data of linear sweep voltammetries (LSV) applied to a Neosepta BP membrane [ 37 ]. …”

“…Cho et al [ 36 ] studied LiOH production from aqueous Li 2 SO 4 solutions by simultaneously concentrating H 2 SO 4 . Recently, González et al [ 37 ] applied bipolar membrane electrodialysis for LiOH production from concentrated lithium chloride solutions (greater than 14% by mass) achieving a LiOH solution of 4.35 mass % (approximately 1.9 M) with a 95.4% purity and a specific 9.45 kWh/kg electricity consumption. In the last years, Tian et al [ 38 ] succeeded in obtaining LiOH concentrations of 3.57 M by experimenting with initial solutions of 70–130 g/L LiCl.…”

“…BMED application for lithium hydroxide production from concentrated LiCl brines represents an implementation opportunity for a complementary green process for lithium compounds production due to its potential integration with solar photovoltaic energy [ 26 ]. To obtain LiOH solutions at concentrations higher than 3.0 mass %, it is necessary to overcome existing membrane limitations at high concentrations such as OH − ion leakage in the cationic membrane and salt leakage in bipolar membranes [ 37 ]. Laboratory experimental study is useful for direct measurement of different parameters effects in the process such as electrolyte concentration and conductivity, electric current and voltage, among others.…”

“…However, it can be expensive due to the chemical reagents' high consumption to prepare concentrated solutions in addition to the current high costs of commercial bipolar and monopolar membranes. Given demonstrated technical feasibility of LiOH production by BMED [ 37 ], it is necessary to develop tools to estimate process performance under different conditions.…”

The effect of two anionic membranes (AMI 7001s and Neosepta AMX) on the electrodeposition of manganese from sulphate solutions

“…The two anion exchange membranes evaluated were Neosepta AMX and AMI 7001s and the individual properties of each membrane are provided in Table 1. 27,[29][30][31]…”