Durability testing for the recovery of sodium hydroxide from alkaline waste solutions

Testing successfully demonstrated the operation of an electrochemical flow cell for more than 1000 h to recover 13-14 wt% sodium hydroxide from an alk aline waste solution. The nickel cathode, platinized-titanium anode and cat ionic membrane exhibited no visible signs of attack upon inspection after t esting. The membrane experienced a slow, but steady decline in current effi ciency, from a high of greater than 95% down to approximately 90% after 107 9 h. We attribute the loss in current efficiency to the accumulation of sil icon and aluminium within the membrane structure.