Bipolar Membrane Electrodialysis for Sulfate Recycling in the Metallurgical Industries

Abstract

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.

Determination of Ionic Diffusion Coefficients in Ion‐Exchange Membranes: Strong Electrolytes and Sulfates with Dissociation Equilibria

“…AR103P and CR61P from Suez Water Technologies and Solutions are reinforced membranes composed of inert reinforcing fibers and ion-exchange resins. [1] The chemical structures of their ionexchange polyelectrolytes are shown, in Ref. [38], Ref.…”

“…Membrane separation processes are employed in the research and applications of various wastewater treatment processes. Examples of such include the usage of bipolar electrodialysis to treat sodium sulfate stemming from the growing lithium-ion battery industry, [1] reverse electrodialysis, [2] membrane-assisted capacitive deionization, [3] desalination and chemical recovery applications, [1,4] water electrolysis, [5] water-splitting in photoelectrochemical cells, [6] and fuel cells. [7][8][9] A detailed theoretical study of ion transport inside the membrane has already been published in various articles and books.…”

Recovery of Ca2+ and SO4 2- from Bittern Wastewater using Electrodialysis Method

“…The highest recirculation flow rate applied at the process, alongside low electric current, affected common ions transportation removal and recovery. As the increasing temperature applied to the process was influenced by both the voltage and current efficiency of the process, it is desirable to operate the system at the maximum temperature that the membrane can endure [18]. A previous study stated that although sulfate is not a direct threat to the environment, sulfate is a nonvolatile, chemically inert, and nontoxic compound, hence being one of the critical nutrients.…”

Bipolar membrane electrodialysis of Na2CO3 and industrial green liquor for producing NaOH: A sustainable solution for pulp and paper industries

“…A drastic decrease in pH resulted in CO 2 release in the recovery cell, leading to sodium sulfate solution that can be used as a new feed to a BPED cell to generate NaOH and sulfuric acid [8]. A BPED system in a batch feed and bleed mode in a 5-compartment setup was reported in our previous paper [9]. Pure sodium sulfate and sulfate-rich industrial effluents were used as the feed, and higher than 80% current efficiency and 95% purity of products was achieved [9].…”

“…A BPED system in a batch feed and bleed mode in a 5-compartment setup was reported in our previous paper [9]. Pure sodium sulfate and sulfate-rich industrial effluents were used as the feed, and higher than 80% current efficiency and 95% purity of products was achieved [9]. In the same way, using BPED technology, green liquor directly from pulp and paper mills can be efficiently converted into NaOH and alkaline carbonate-rich solution to capture H 2 S and CO 2 separately.…”