The Novel Strategy for Increasing the Efficiency and Yield of the Bipolar Membrane Electrodialysis by the Double Conjugate Salts Stress

Abstract

To improve sulfuric acid recovery from sodium sulfate wastewater, a lab-scale bipolar membrane electrodialysis (BMED) process was used for the treatment of simulated sodium sulfate wastewater. In order to increase the concentration of sulfuric acid (H2SO4) generated during the process, a certain concentration of ammonium sulfate solution was added into the feed compartment. To study the influencing factors of sulfuric acid yield, we prepared different concentrations of ammonium sulfate solution, different feed solution volumes, and different membrane configurations in this experiment. As it can be seen from the results, when adding 8% (NH4)2SO4 into 15% Na2SO4 under the experimental conditions where the current density was 50 mA/cm2, the concentration of H2SO4 increased from 0.89 to 1.215 mol/L, and the current efficiency and energy consumption could be up to 60.12% and 2.59 kWh/kg, respectively. Furthermore, with the increase of the volume of the feed compartment, the concentration of H2SO4 also increased. At the same time, the configuration also affects the final concentration of the sulfuric acid; in the BP-A-C-BP (“BP” means bipolar membrane, “A” means anion exchange membrane, and “C” means cation exchange membrane; “BP-A-C-BP” means that two bipolar membranes, an anion exchange membrane, and a cation exchange membrane are alternately arranged to form a repeating unit of the membrane stack) configuration, a higher H2SO4 concentration was generated and less energy was consumed. The results show that the addition of the double conjugate salt is an effective method to increase the concentration of acid produced in the BMED process.

Investigation of Itaconic Acid Separation by Operating a Commercialized Electrodialysis Unit with Bipolar Membranes

“…The mentioned decreasing trend was caused by the reduced influence of hydroxide (OH − ) and hydrogen (H + ) ions generated by the bipolar membranes during the separation process. Similar phenomena were reported by Wang et al [30].…”

“…The mentioned decreasing trend was caused by the reduced influence of hydroxide (OH − ) and hydrogen (H + ) ions generated by the bipolar membranes during the separation process. Similar phenomena were reported by Wang et al [30]. During the separation process, mobile ions were transferred, while water dissociation (H 2 O → H + + OH − ) was induced by bipolar membranes (Figure 1), causing low resistance level of all the segments (Figure 3).…”

Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives

“…Phosphogypsum (CaSO 4 ) by-product from phosphoric acid production can be converted by NaOH into Ca(OH) 2 and Na 2 SO 4 , thus splitting the salt into base and sulphuric acid via BMED [ 273 ]. Other applications were proposed to convert NH 4 Cl into HCl and NH 3 [ 274 , 275 ], NH 4 HCO 3 into NH 3 and CO 2 [ 276 ], Na 3 PO 4 into H 3 PO 4 and NaOH [ 277 ], NaBr into HBr and NaOH [ 278 , 279 ], Na 2 SO 4 /(NH 4 ) 2 SO 4 into H 2 SO 4 and NaOH/NH 3 [ 280 ], NaCl/KCl into HCl and NaOH/KOH [ 281 ], boron into boric acid [ 282 , 283 , 284 ].…”

Performance Optimization of Bipolar Membrane Electrodialysis of Ammonium Sulfate/Bisulfate Reagents for CO2 Mineralization

“…Several different arrangements of BPMED have been tested previously, which use ammonium sulfate as input species. − With regard to the separation of ABS, however, there are almost no publications available, except for work published by the authors of this paper. , Direct CO 2 capture in the BPMED unit using processes that include the precipitation of carbonates inside the BPMED unit has also been investigated. , Such precipitation is avoided in the mineral carbonation route presented here.…”