The behaviour of Nafion® 424 membrane in the electrochemical production of lithium hydroxide

BACKGROUNDNafion (R) membranes have found several applications in chemical processes, one of which is salt splitting', where a salt is split to produce acid and/or alkali. So, the determination of the behaviour of this membrane in the electrolysis of certain salts is an important issue. The aim of this study is to investigate the performance of Nafion (R) 424 membrane in a two-compartment membrane cell for the membrane electrolysis of lithium sulphate (Li2SO4), where lithium hydroxide (LiOH) is the target product. RESULTSRegression analysis was performed between conductivity and concentration to predict instantaneous electrolyte concentration. The effects of catholyte concentration (4-8% LiOH), current density (4-16 A dm(-2)) and temperature (30-60 degrees C) were investigated. 45-70% current efficiency; 6.1-14.6 kWh kg(-1) LiOH power consumption and 140-900g LiOH m(-2) membrane h(-1) production rate were obtained. A cost estimation revealed that 60 degrees C, 8% LiOH and 4 A dm(-2) are the optimum parameters within the studied range. CONCLUSIONConcentration can be successfully predicted for lithium sulphate and lithium hydroxide with the help of conductivity-concentration regression equations. Current efficiency is affected primarily by LiOH concentration with a direct proportion. Power consumption increases with the increase of current density and the decrease of temperature. Based on production cost estimation, optimum working parameters can be recommended. (c) 2015 Society of Chemical Industry