NaOH recovery from waste stream of merox process using electrodialysis

The recovery of NaOH from the waste stream of Merox process containing metallic salts (Na2S, Na2CO3 and NaOH) was achieved by the electrodialysis (ED) process with two different configurations of two and three-compartment cell in batch mode. In the experiments, base solution was used as catholyte and an acid solution were used as an anolyte. The effects of feed flow rate, applied voltage and feed concentration on the NaOH recovery were investigated and discussed. The separation performance was evaluated in terms of sodium ion transfer and electricity consumption. The obtained results showed that electrodialysis seems to be an applicable method for the recovery of NaOH from waste stream of Merox process at suitable conditions. High NaOH recovery was obtained by the electrodialysis at about 75%.