Treatment Of Sulfanilic Acid Wastewater By Bipolar Membrane Electrodialysis

Bipolar membrane electrodialysis(BMED)can remove inorganic salts from wastewater and convert into corresponding acids and bases,which is an effective treatment method to hypersaline wastewater.In this paper,BMED was applied to the desalination treatment of sulfanilic acid wastewater.The main work is as follows:A BMED system with three compartments(BP-A-C)was used in this study,and the influence of current density,initial concentrations of acid and base,liner velocity and initial concentration of sodium chloride was investigated.Desalination rate,recovery concentrations of acid and base,current efficiency and energy consumption were used to access the performance of BMED.The results showed that the desalination rate was about 97%when the current density was 40 m A/cm~2,the initial concentrations of acid and base were both 0.10mol/L,the liner velocity was 4.0 cm/s,and the initial concentration of sodium chloride was 80g/L.Under these conditions,the concentrations of recovery acid and base were 1.17 mol/L and 1.18 mol/L,respectively,while the current efficiency and energy consumption were58.9%and 1.86 k Wh/kg NaOH,respectively.A multi-factor model for the treatment of sulfanilic acid simulated wastewater by BMED was established using a Box-Behnken response surface design with four factors and three levels.The optimal operating conditions obtained by model analysis were as follows:the current density was 30 m A/cm~2,the initial concentrations of acid and base were 0.06 mol/L,the liner velocity was 3.0 cm/s,and the initial concentration of sodium chloride was 50 g/L.The current efficiency and energy consumption predicted by the model were 66.5%and 1.43k Wh/kg NaOH,respectively.Verification tests confirmed the good predictability and high accuracy of the model.In order to investigate the stability of BMED process for the treatment of sulfanilic acid simulated wastewater,the cycle experiments were carried out under the optimal operating conditions obtained by the model analysis,which demonstrated the good stability and repeatability of the experiments.The results showed that the desalination rate was about 97%,the concentrations of recovery acid and base were 1.14 mol/L and 1.19 mol/L,respectively,while the concentration of sulfanilic acid in the acid compartment and base compartment were only about 260 mg/L and 25 mg/L,respectively,the current efficiency and energy consumption were 58.2%and 1.65 k Wh/kg NaOH,respectively.Comparing with the results under the optimal operating conditions obtained by the single-factor experiments,the energy consumption was reduced 12.73%without significant change of the current efficiency.Process economic analysis showed that the energy consumption cost was only 1.11 yuan/kg NaOH,and the total cost was 12.32 yuan/kg NaOH.