Boron Removal from Reverse Osmosis Permeate Using an Electrosorption Process: Feasibility, Kinetics, and Mechanism

Sun, Jingyi; Zhang, Changyong; Song, Zhao; Waite, T. David

doi:10.1021/acs.est.2c02297

Cited by 21 publications

(14 citation statements)

References 43 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, no apparent difference in pH variation was observed in the absence and presence of NO 3 – (SI Figure S5), suggesting the pH increase was mainly due to the occurrence of water electrolysis and/or oxygen reduction. This finding is also supported by our previous study, which also showed that water electrolysis is the major cause of pH increase at a cell voltage >2.3 V . The increase in pH changes the speciation of NH 4 + (p K a = 9.2) to NH 3, thereby facilitating stripping of NH 3 by the FGM-attached acid-receiving chamber.…”

Section: Resultsmentioning

confidence: 98%

Electrochemical Reduction of Nitrate with Simultaneous Ammonia Recovery Using a Flow Cathode Reactor

Sun

Garg

Xie

et al. 2022

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

The presence of excessive concentrations of nitrate in industrial wastewaters, agricultural runoff, and some groundwaters constitutes a serious issue for both environmental and human health. As a result, there is considerable interest in the possibility of converting nitrate to the valuable product ammonia by electrochemical means. In this work, we demonstrate the efficacy of a novel flow cathode system coupled with ammonia stripping for effective nitrate removal and ammonia generation and recovery. A copper-loaded activated carbon slurry (Cu@AC), made by a simple, low-cost wet impregnation method, is used as the flow cathode in this novel electrochemical reactor. Use of a 3 wt % Cu@AC suspension at an applied current density of 20 mA cm −2 resulted in almost complete nitrate removal, with 97% of the nitrate reduced to ammonia and 70% of the ammonia recovered in the acid-receiving chamber. A mathematical kinetic model was developed that satisfactorily describes the kinetics and mechanism of the overall nitrate electroreduction process. Minimal loss of Cu to solution and maintenance of nitrate removal performance over extended use of Cu@AC flow electrode augers well for long-term use of this technology. Overall, this study sheds light on an efficient, low-cost water treatment technology for simultaneous nitrate removal and ammonia generation and recovery.

show abstract

Section: Resultsmentioning

confidence: 98%

Electrochemical Reduction of Nitrate with Simultaneous Ammonia Recovery Using a Flow Cathode Reactor

Sun

Garg

Xie

et al. 2022

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Another electrosorption configuration that has recently demonstrated boron removal capability resembles membranecapacitive deionization (MCDI). 23 However, unlike conventional MCDI, only an anion-exchange membrane is placed in front of the anode, while the cathode remains bare. Thus, when sufficiently high potentials are applied (i.e., >2.0 V used in the study), oxygen reduction and water splitting are induced at the cathode, in turn producing hydroxide ions which migrate to the flow channel.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Another electrosorption configuration that has recently demonstrated boron removal capability resembles membrane-capacitive deionization (MCDI) . However, unlike conventional MCDI, only an anion-exchange membrane is placed in front of the anode, while the cathode remains bare.…”

Section: Resultsmentioning

confidence: 99%

“…When the electric potential is removed or reversed, the ions are released from the EDLs back into the solution, producing a brine stream and regenerating the electrode sorption sites . Electrosorption performs most efficiently for low salinity waters and small extents of ion removal; , hence, its use for trace boron removal (e.g., from seawater RO permeate) is expected to be an energetically favorable application of the technology which, aside from a few recently proposed schemes, , remains largely unexplored. For the electrosorption of boron at the anode, however, boric acid (p K a ∼ 9.1) must be ionized to borate under high pH conditions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrosorption Integrated with Bipolar Membrane Water Dissociation: A Coupled Approach to Chemical-free Boron Removal

Patel

Pan

Shin

et al. 2023

Environ. Sci. Technol.

View full text Add to dashboard Cite

Boron removal from aqueous solutions has long persisted as a technological challenge, accounting for a disproportionately large fraction of the chemical and energy usage in seawater desalination and other industrial processes like lithium recovery. Here, we introduce a novel electrosorption-based boron removal technology with the capability to overcome the limitations of current state-of-the-art methods. Specifically, we incorporate a bipolar membrane (BPM) between a pair of porous carbon electrodes, demonstrating a synergized BPM–electrosorption process for the first time. The ion transport and charge transfer mechanisms of the BPM–electrosorption system are thoroughly investigated, confirming that water dissociation in the BPM is highly coupled with electrosorption of anions at the anode. We then demonstrate effective boron removal by the BPM–electrosorption system and verify that the mechanism for boron removal is electrosorption, as opposed to adsorption on the carbon electrodes or in the BPM. The effect of applied voltage on the boron removal performance is then evaluated, revealing that applied potentials above ∼1.0 V result in a decline in process efficiency due to the increased prevalence of detrimental Faradaic reactions at the anode. The BPM–electrosorption system is then directly compared with flow-through electrosorption, highlighting key advantages of the process with regard to boron sorption capacity and energy consumption. Overall, the BPM–electrosorption shows promising boron removal capability, with a sorption capacity >4.5 μmol g-C–1 and a corresponding specific energy consumption of <2.5 kWh g-B–1.

show abstract

“…5,6 Thus, it holds great promise to alleviate, or at least change the dynamics of, the worldwide water scarcity problem. 7,8 The desalination performance of a CDI system is intrinsically associated with the employed electrode materials, so researchers are dedicated to exploring novel electrode materials with a high desalination capacity to accelerate the industrial process of the technology. In response, by virtue of their multiple merits of metal-grade conductivity (6500 S cm −1 ), high volumetric capacitance (1500 F cm −3 ), and unique layered structure allowing rapid ion de-/intercalation, twodimensional transition metal carbides/nitrides (e.g., M n+1 X n , where M is the transition metal and X is carbon or nitrogen), commonly referred to as MXenes, may serve as one of the most promising faradic pseudocapacitance electrode materials and, correspondingly, have great prospects for use in CDI technology.…”

Section: ■ Introductionmentioning

confidence: 99%

Interlayer Structure and Chemistry Engineering of MXene-Based Anode for Effective Capture of Chloride Anions in Asymmetric Capacitive Deionization

Tan

Wang

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Negatively charged surfaces and readily oxidizabile characteristics fundamentally restrict the use of MXene building blocks as anodes for anion intercalation. Herein, by embedding bacterial cellulose nanofibers with conformal polypyrrole coating (BC@PPy) and populating them between MXene (Ti 3 C 2 T x ) interlayers, we enable the fabricated MXene/BC@PPy (MBP) composite films to be highly efficient anodes for Cl − -capturing in asymmetric capacitive deionization (CDI) systems. Performance gains are realized due to the surface electronegativity of MXene nanosheets becoming compensated by positively charged BC@PPy nanofibers, alleviating electrostatic repulsion, thus realizing reversible Cl − intercalation. More crucially, the anodization voltage of MBP is effectively enhanced as a result of the increase of the Ti valence state in MXene nanosheets with the addition of the BC@ PPy spacer. Furthermore, BC@PPy nanopillars effectively enlarge the interlayer space for facile Cl − de-/intercalation, improve the vertical electron transfer between loosely deposited MXene nanosheets, and perform as additional active materials for Cl − -capturing. Consequently, the MBP anode exhibits a promising desalination capacity of up to 17.56 mg g −1 at 1.2 V with a high capacity retention of 94.6% after 30 cycles in an asymmetric CDI system. This work offers a simple and effective strategy to unlock the application potential of MXene building blocks as anodes for Cl − -capturing in electrochemical desalination.

show abstract

Boron Removal from Reverse Osmosis Permeate Using an Electrosorption Process: Feasibility, Kinetics, and Mechanism

Cited by 21 publications

References 43 publications

Electrochemical Reduction of Nitrate with Simultaneous Ammonia Recovery Using a Flow Cathode Reactor

Electrochemical Reduction of Nitrate with Simultaneous Ammonia Recovery Using a Flow Cathode Reactor

Electrosorption Integrated with Bipolar Membrane Water Dissociation: A Coupled Approach to Chemical-free Boron Removal

Interlayer Structure and Chemistry Engineering of MXene-Based Anode for Effective Capture of Chloride Anions in Asymmetric Capacitive Deionization

Contact Info

Product

Resources

About