Enhancement of the current efficiency for sodium hydroxide production from sodium sulphate in a two-compartment bipolar membrane electrodialysis system

The objective of this work was to determine the process conditions for converting sodium acetate, the major component of alkaline hardwood extract, into acetic acid and sodium hydroxide using bipolar membrane electrodialysis (BPMED). The effects of current density and sodium acetate concentration in the feed-salt solution were evaluated using synthetic sodium acetate solution in a feed and bleed mode. This mode of operation represents semibatch processing and was useful for determining the current efficiencies, energy consumption, and other system parameters for the production of about 160 g/L of acetic acid; maximum achievable concentration of acetic acid in electrodialysis; and 30 g/L of sodium hydroxide, which is the concentration sufficient for the extraction of sodium acetate from hardwood. The feed and bleed mode experiments performed at 60 mA/cm2 using 130 and 85 g/L sodium acetate as feed-salt solutions produced similar results, except for a small change in the amount of water transported into the acid and base compartments. The feed and bleed mode experiment performed at low current density of 40 mA/cm2 using 50 g/L sodium acetate as feed-salt solution produced almost similar quantities of acetic acid and sodium hydroxide as those in the other feed and bleed mode experiments. However, the energy consumption and current efficiencies were lower than those for the experiments performed at the current density of 60 mA/cm2.

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A environmentally friendly process for boric acid and sodium hydroxide production from borax; bipolar membrane electrodialysis

Desalination and Water Treatment ◽

10.1080/19443994.2015.1107509 ◽

2015 ◽

Vol 57 (43) ◽

pp. 20261-20269

Author(s):

Jülide Erkmen ◽

Sinan Yapici

Keyword(s):

Boric Acid ◽

Sodium Hydroxide ◽

Environmentally Friendly ◽

Bipolar Membrane ◽

Bipolar Membrane Electrodialysis ◽

Environmentally Friendly Process

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Two-compartment bipolar membrane electrodialysis for splitting of sodium formate into formic acid and sodium hydroxide: Modelling

Journal of Membrane Science ◽

10.1016/j.memsci.2008.10.058 ◽

2009 ◽

Vol 328 (1-2) ◽

pp. 75-80 ◽

Cited By ~ 26

Author(s):

J.S. Jaime-Ferrer ◽

E. Couallier ◽

P. Viers ◽

M. Rakib

Keyword(s):

Formic Acid ◽

Sodium Hydroxide ◽

Sodium Formate ◽

Bipolar Membrane ◽

Bipolar Membrane Electrodialysis

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Bipolar Membrane Electrodialysis for Sulfate Recycling in the Metallurgical Industries

Membranes ◽

10.3390/membranes11090718 ◽

2021 ◽

Vol 11 (9) ◽

pp. 718

Author(s):

Kuldeep ◽

Wouter Dirk Badenhorst ◽

Pertti Kauranen ◽

Heikki Pajari ◽

Ronja Ruismäki ◽

...

Keyword(s):

Ion Exchange ◽

Current Efficiency ◽

Environmental Sustainability ◽

Exchange Capacity ◽

Effect Of Temperature ◽

Bipolar Membrane ◽

Cobalt Sulfate ◽

Payback Time ◽

Bipolar Membrane Electrodialysis ◽

Waste Effluents

Demand for nickel and cobalt sulfate is expected to increase due to the rapidly growing Li-battery industry needed for the electrification of automobiles. This has led to an increase in the production of sodium sulfate as a waste effluent that needs to be processed to meet discharge guidelines. Using bipolar membrane electrodialysis (BPED), acids and bases can be effectively produced from corresponding salts found in these waste effluents. However, the efficiency and environmental sustainability of the overall BPED process depends upon several factors, including the properties of the ion exchange membranes employed, effluent type, and temperature which affects the viscosity and conductivity of feed effluent, and the overpotentials. This work focuses on the recycling of Na2SO4 rich waste effluent, through a feed and bleed BPED process. A high ion-exchange capacity and ionic conductivity with excellent stability up to 41 °C is observed during the proposed BPED process, with this temperature increase also leading to improved current efficiency. Five and ten repeating units were tested to determine the effect on BPED stack performance, as well as the effect of temperature and current density on the stack voltage and current efficiency. Furthermore, the concentration and maximum purity (>96.5%) of the products were determined. Using the experimental data, both the capital expense (CAPEX) and operating expense (OPEX) for a theoretical plant capacity of 100 m3 h−1 of Na2SO4 at 110 g L−1 was calculated, yielding CAPEX values of 20 M EUR, and OPEX at 14.2 M EUR/year with a payback time of 11 years, however, the payback time is sensitive to chemical and electricity prices.

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