Investigation of Current Routes in Electrodeionization System Resin Beds During Chromium Removal

Agricultural development, extensive industrialization, and rapid growth of the global population have inadvertently been accompanied by environmental pollution. Water pollution is exacerbated by the decreasing ability of traditional treatment methods to comply with tightening environmental standards. This review provides a comprehensive description of the principles and applications of electrochemical methods for water purification, ion separations, and energy conversion. Electrochemical methods have attractive features such as compact size, chemical selectivity, broad applicability, and reduced generation of secondary waste. Perhaps the greatest advantage of electrochemical methods, however, is that they remove contaminants directly from the water, while other technologies extract the water from the contaminants, which enables efficient removal of trace pollutants. The review begins with an overview of conventional electrochemical methods, which drive chemical or physical transformations via Faradaic reactions at electrodes, and proceeds to a detailed examination of the two primary mechanisms by which contaminants are separated in nondestructive electrochemical processes, namely electrokinetics and electrosorption. In these sections, special attention is given to emerging methods, such as shock electrodialysis and Faradaic electrosorption. Given the importance of generating clean, renewable energy, which may sometimes be combined with water purification, the review also discusses inverse methods of electrochemical energy conversion based on reverse electrosorption, electrowetting, and electrokinetic phenomena. The review concludes with a discussion of technology comparisons, remaining challenges, and potential innovations for the field such as process intensification and technoeconomic optimization.

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Section: Electrokinetic Separationsmentioning

confidence: 99%

Electrochemical Methods for Water Purification, Ion Separations, and Energy Conversion

et al. 2022

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“…To pinpoint the electrolyte concentration range that minimizes the effects of resin conductivity in EXS, we determined the ECP for both WAC and SAC. At the ECP, cell conductivity equals the interstitial solution conductivity (dotted line in Figure 2e), 50 meaning the electrolyte conducts most of the ions and the resin negligibly affects the cell resistance. 33 The cell ECP was 4.5 and 11.5 mS/cm for WAC and SAC, respectively, which indicated that WAC was appreciably involved in ion transport only when electrolyte conductivity was as low as 4.5 mS/cm (∼40 mM as KCl) compared to SAC at 11.5 mS/cm (∼100 mM as KCl).…”

Section: Mechanisms Of Resin Regeneration: Comparing Potassium Ions I...mentioning

confidence: 99%

Electrified Ion Exchange Enabled by Water Dissociation in Bipolar Membranes for Nitrogen Recovery from Source-Separated Urine

Dong

Laguna

Liu

et al. 2022

Environ. Sci. Technol.

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Ion exchange (IX) is a promising technology for selective nitrogen recovery from urine; however, IX requires chemical-intensive regeneration that escalates energy consumption and carbon emissions. To overcome this barrier, we demonstrated and investigated a novel electrified IX stripping process (EXS) enabling electrochemical in situ IX regeneration with simultaneous ammonia stripping. EXS combines a weak acid cation exchange resin (WAC) to concentrate ammonia, a bipolar membrane to produce protons for WAC regeneration, and membrane stripping to recover the eluted ammonium from WAC. We observed over 80% regeneration (elution from resin) and recovery (membrane stripping) efficiencies during multiple adsorption–recovery cycles with synthetic and real urine. Comparing WAC with a strong acid cation exchange resin illustrated the critical role of the proton affinity of resin moieties in regulating resin regenerability and conductivity in EXS, which we distinguished from the rationale for material choice in electrodeionization. Compared to other electrochemical recovery methods using unamended wastewater as an electrolyte, EXS enabled control of electrolyte composition during recovery by separating and equalizing influent ammonium via WAC-mediated removal. This electrolyte engineering facilitated tunable EXS energy efficiency (100–300 MJ/kg N). This study informs the design of electrified, intensified systems that enable decentralized nitrogen recovery from urine.

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“…36,37 It should be pointed out that in a EDI system, the ion-exchange resin bed plays a major role as a permanent ionic conductive medium in the diluate compartment, 38 while the ion exchange membranes lead to the depletion and concentration of the solutions, respectively. 39,40 Therefore, EDI has received great attention in purification of wastewater containing metal ions in recent years (Table S1).…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

“…Although CED qualifies as an effective technology for removal of metal ions, the cell resistance increases when the ions are removed from the diluate compartment, which results in higher energy consumption and lower efficiency to remove metal ions. , In order to facilitate the ion transport rate in CED, electrodeionization (EDI) has also been employed for the effective removal of metal ions, particularly when the concentrations of metal ions are low and a polarization concentration phenomenon emerges. ,, Furthermore, EDI reduces the energy consumption when the feed conductivity is low (lower than 500 μS/cm) in comparison to the amounts used for CED. , It should be pointed out that in a EDI system, the ion-exchange resin bed plays a major role as a permanent ionic conductive medium in the diluate compartment, while the ion exchange membranes lead to the depletion and concentration of the solutions, respectively. , Therefore, EDI has received great attention in purification of wastewater containing metal ions in recent years (Table S1).…”

Section: Recovery Of Inorganic Saltmentioning

confidence: 99%

Waste Conversion and Resource Recovery from Wastewater by Ion Exchange Membranes: State-of-the-Art and Perspective

Zhao

Zhou

Yan

et al. 2018

Ind. Eng. Chem. Res.

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Wastewater treatment is in a dilemma: more energy and efforts have to be put forth to obtain an effluent with better quality, while a significant amount of sludge is generated and the treatment or disposal expenses are high. Even if the sludge is disposed of properly, the components can be released and pollute the environment again. Therefore, conversion and recovery of the contaminants to resources is the way out of the dilemma. An ion exchange membrane (IEM) is a special type of membrane, which allows charged solutes to pass through it while retaining uncharged components. Attributed to this character, IEMs are taking more important roles in separation and conversion processes recently. They act as key elements in many resource recovery systems, such as in separation and concentration, salt valorization, energy conversion, and even in microbial systems. This review summarizes the important processes for waste conversion and resource recovery from wastewaters by using IEMs. Drawbacks and perspectives are summarized in view of the development of the processes and the membranes.

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Investigation of Current Routes in Electrodeionization System Resin Beds During Chromium Removal

Cited by 17 publications

References 20 publications

Electrochemical Methods for Water Purification, Ion Separations, and Energy Conversion

Electrochemical Methods for Water Purification, Ion Separations, and Energy Conversion

Electrified Ion Exchange Enabled by Water Dissociation in Bipolar Membranes for Nitrogen Recovery from Source-Separated Urine

Waste Conversion and Resource Recovery from Wastewater by Ion Exchange Membranes: State-of-the-Art and Perspective

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