Ion Removal Performance Research Articles

Adsorption of fluoride ion on Al/La modified acidified attapulgite composite materials

This study developed a novel fluoride ion adsorbent material (Al/La-A) for efficient removal of fluoride ions in water. The crystal structure, elemental composition, surface morphology, specific surface area, thermal stability and surface electronegativity before and after modification were explored using FTIR, XRD, XPS, SEM-EDS, BET, TG-DSC, and zeta potential measurements. Results showed that the fluoride ion adsorption capacity of Al/La-A reached 130.42 mg/g, with the surface area increasing from 65.66 m2/g to 111.68 m2/g, respectively, compared to unmodified attapulgite. Al/La-A maintained excellent fluoride ion removal performance over a wide pH range, with the best adsorption at pH 2. Coexisting ion experiments indicated weak competitive adsorption effects of Cl-, SO42-, and HCO3–, with fluoride ion adsorption remaining above 100 mg/g in the presence of different concentrations of coexisting anions. After 5 adsorption–desorption cycles, Al/La-A exhibited strong adsorption capacity and reusability. The fitting of Langmuir adsorption model and pseudo-second-order kinetic model to the adsorption of fluoride ions on Al/La-A indicated that the adsorption of fluoride ions on Al/La-A was primarily monolayer chemical adsorption. The adsorption mechanism of fluoride ions involved electrostatic interactions, ion exchange, and coordination complexation. This study provides a new research approach for the optimal utilization of attapulgite-based adsorbent materials and the efficient removal of fluoride-containing wastewater.

Green synthesis and high-performance fluoride ion removal using lanthanum-modulated MOF-808 (Zr)

In a water solution and with a low reaction temperature of 85 °C, the green preparation of lanthanum-modulated MOF-808 (Zr) was realized, the obtained La-MOF-808 have smaller grain size, larger specific surface area, higher pore volume and larger average pore diameter. When the molar ratio of La: Zr=1:1, 1L-MOF-808 had the best fluoride ion removal performance, and its maximum adsorption capacity for F- reached 101.4 mg/g, which was higher than that of the unmodulated MOF-808 and some other reported fluorine adsorbents. Meanwhile, the regeneration experiment demonstrated that even after five cycles, 1L-MOF-808 retained 73.8 % of its initial adsorption capacity, highlighting its commendable reusability. In addition, when 1L-MOF-808 was applied to actual fluorine-containing wastewater, with the fluoride ion concentration of 25.3 mg/L and an adsorbent dosage of 0.6 g/L, 1L-MOF-808 exhibited excellent resistance to anionic interference (SO42-, Cl-), the concentration of fluoride ions in effluent was lower than 10 mg/L, meeting the stipulations of fluoride ion discharge outlined in GB39371–2020. Further adsorption mechanism investigation revealed that 1L-MOF-808's affinity for F- was attributed to electrostatic interaction and ligand exchange. Overall, the as-synthesized 1L-MOF-808 not only presents an environmentally friendly approach to producing MOF materials without organic solvents but also develops a new strategy for the design of high-performance adsorbent for effectively removing fluoride ions from wastewater.

Enhanced separation of dual pollutants from wastewater containing Cr (Ⅵ) and oil via Fe-doped sludge derived membrane

One-step separation of multi-component contaminants in chemical separations by a single material is essential to simplify the separation process and enhance the separation efficiency. This work proposed an eco-friendly and effective “cation doping” strategy, utilizes waste river sludge (RS) as raw material, incorporates Fe to improve ion removal performance, and the Fe-doped RS/PVDF membrane was obtained for simultaneously removing Cr (Ⅵ) and oil from electroplating wastewater. The membrane exhibits outstanding rejection rates for oil (>98 %) and Cr (Ⅵ) (89.10 %), which was superior to Cr (Ⅵ) rejection rate of RS/PVDF membrane (22.04 %) without Fe doping under the combined action of electrostatic attraction, surface complexation, redox, and the superhydrophilic/underwater oleophobicity. Notably, protonation and low operating pressure contributed to Cr (Ⅵ) removal, and the membrane presents satisfactory acid-alkali resistance, anti-interference ions ability and chemical stability. Therefore, this work offers a novel development strategy for affordable and effective multifunctional separation membrane, and also promotes the realization of simultaneous and rapid removal of heavy metal ions and oil contaminants, which is encouraging in terms of potential industrial applications.

Simultaneous removal of tetracycline and copper ions from wastewater by flow-electrode capacitive deionization

ABSTRACT To effectively solve the problem of tetracycline (TC) and Cu2+ contamination in wastewater, this study innovatively proposed a low-energy flow-electrode capacitive deionization (FCDI) technology to simultaneously remove TC and Cu2+ from wastewater. The removal efficiencies of TC and Cu2+ using FCDI was investigated under various voltages, electrode flow rates, influent flow rates, and electrode liquid concentrations. The results showed that the removal efficiency of TC and Cu2+ was 60.78% and 84.43%, respectively. The energy consumption for TC and Cu2+ removal was only 1.76 and 1.10 kWh kg−1, which was lower than other electrochemical systems. The ion removal performance of the FCDI system remained stable after six cycles of continuous operation. These findings demonstrated the promising potential of FCDI as an innovative technology for the simultaneous removal of TC and Cu2+, presenting a significant prospects for application in the water treatment field.

Three-segmented counterflow pilot-scale electrodialysis for ammonia and potassium treatment in liquid anaerobic digestate: A trade-off among advanced ion removal, nutrients concentration limitation, and energy consumption

In this paper, a three-segmented counterflow (COUN) electrodialysis (ED) for ammonia (NH4+-N) and potassium (K+) treatment in liquid anaerobic digestate (LAD) was proposed to break the high-concentration limit of nutrient recovery without sacrificing the ion removal performance and energy efficiency. The effects of the COUN operation mode on ED performance were studied based on pilot-scale experiments. The results indicate that the COUN mode improves the distribution of concentration difference (Δc). Hence, the ion fluxes of NH4+-N and K+ have increased by 51.0% and 25.3%, respectively. A highly concentrated product (NH4+-N at 10428 ± 225 mg/L and K+ at 7500 ± 156 mg/L) can be obtained, and the concentration multiples of NH4+-N and K+ have increased by 14.1% and 9.8%, respectively, with slight effects on their removal rates. The current efficiency for NH4+-N and K+ was increased by 38.1% and 14.5%, reaching 54.7 ± 3.5% and 12.4 ± 0.5%, respectively, and the final energy consumption of 3.8 ± 0.2 kWh/kg-N) has reduced by 31.8%. The non-ideal transport mechanisms associated with the Δc (back-diffusion and water osmosis) have been taken into consideration. The COUN mode is a new exploration of the ED operating patterns to alleviate the detrimental effect of high Δc. It will provide a reference for designing and operating large-scale engineering projects for nutrient recovery by ED process and a trade-off among advanced ion removal, high-concentration limitation, and energy consumption.

Customized copper/cobalt-rich ferrite spinel-based construction ceramic membrane incorporating gold tailings for enhanced treatment of industrial oily emulsion wastewater

New ceramic membranes (CM) using environment-oriented materials instead of rare materials are more attractive and easier to large-scale engineering and promotion. In this study, the feasibility of customizing low-cost and robust CM, is investigated by sintering typical available solid wastes (Fe-S-rich gold tailings and Si-rich marine shellfish powder) as the matrix with copper/cobalt-rich precursors. Analysis results indicate that the precursors (Cobaltate and Cuprate) with the proposed ratio (1:1 by mass, 1300 °C) can be chemically stable crystallized in the more durable structure of customized copper/cobalt-rich ferrite spinel-based construction CM (CM-(Cu-Co)Fe2O4). The composite membrane can operate stably and consumes no additional energy. After detailed characterization of the pore structure, the purification treatment of industrial oily wastewater (rejection rate > 99.9), emulsion oily wastewater (rejection rate > 97.9) and alizarin red wastewater (rejection rate > 99.3) was fully evaluated. Surprisingly, the waste-to-resource CM of CM-(Cu-Co)Fe2O4 exhibits significant heavy metal iron ion removal performance (>94%) due to electrostatic attraction and adsorption. The successful preparation and application of environment-oriented multifunctional CM from a typical solid waste matrix provide a promising strategy of resource recovery for beneficial utilization of ordinary solid wastes with stock as ceramic raw materials.

Design and analysis of chitosan-caffeic acid matrix for wastewater treatment

This study aims to improve the dye and heavy metal ion removal performance of chitosan with caffeic acid functionalization for wastewater treatment applications. Chitosan-caffeic acid matrix (CCM) was synthesized via the amide coupling method then lyophilize resulting in a sponge-like matrix. CCM was applied to simulated wastewater with 40 µM anionic azo dye, Trypan blue, and heavy metal ions including Fe and Pb. The decontamination performance was observed at 1, 2 and 4 h. The results showed that the introduction of caffeic acid in CCM significantly increased the dye removal rate and heavy metal ion removal capability compared to the chitosan without caffeic acid. For future work, determinizing the approximate ratio of caffeic acid and chitosan is necessary to reach the maximum efficiency of CCM.

CNT/copper hexacyanoferrate: A superior Faradic electrode for ammonium ion removal with stable performance and high capacity

The discharge of ammonium ion (NH4+) not only seriously threatens the ecological safety of the environment, but also causes the waste of valuable resources. Capacitive deionization (CDI) is an environmentally friendly and efficient NH4+ ion treatment and recovery technology. Herein, the NH4+-rich copper hexacyanoferrate (N-CuHCF) and carbon nanotube (CNT) complex (CNT/N-CuHCF) was formed by a simple and fast co-precipitation-ion exchange method, and used as the Faradic electrode to store NH4+ in the hybrid capacitive deionization (HCDI) system. Intriguingly, the etching efficiency of the ion exchange process produces the interconnected nanonetwork structure, endows the prepared material with larger surface area and abundant redox active sites, guarantees high pseudocapacitance contribution and reversible NH4+ intercalation/deintercalation, thus enabling an excellent ammonium ion removal performance. The CNT/N-CuHCF demonstrates a superior specific adsorption capacity (SAC) of 120.2 mg g−1, a low specific energy consumption (126.1 kJ molNH4Cl−1), and remarkable cycling stability. In addition, compared with Na+ and Mg2+, CNT/N-CuHCF has better affinity and selectivity for NH4+. The NH4+ intercalation mechanism and structure stabilization mechanism of N-CuHCF were revealed through a series of ex situ characterizations. This work provides some new illuminating insights for the design of high-performance ammonium ion removal CDI electrodes, and lays a foundation for the recovery of ammonium resources.

Synthesis of porous magnetic zeolite-based material and its performance on removal of Cd2+ ion and methylene blue from aqueous solution

In this study, the natural clinoptilolite zeolite was hydrothermally treated and then combined with porous silica-coated magnetic particles to prepare a porous magnetic zeolite-based material. Process parameters such as NaOH concentration, hydrothermal temperature and time, pH value, and Fe3O4/Na2SiO3 ratio were optimized. XRD, XPS, N2 adsorption-desorption technique, SEM-EDX, TEM, FTIR, etc. were employed to investigate the composition and structure of the materials. Cd2+ ion and methylene blue were adopted to evaluate the contamination removal performance of the materials. The results showed that hydrothermal treatment under an alkaline environment could transform clinoptilolite to Na–P zeolite with a low Si/Al ratio and relatively high Cd2+ adsorption capacity. Porous silica-coated magnetite loading could significantly increase the specific surface area of the material and render it magnetic. The as-prepared porous magnetic zeolite-based material exhibited much higher Cd2+ ion and methylene blue removal performance than the raw natural clinoptilolite zeolite.

Ammonia removal from municipal wastewater via membrane capacitive deionization (MCDI) in pilot-scale

With the depletion of energy, renovation of wastewater has attracted wide attention around the world, among which the recovery of ammonia has also been an ongoing topic. Membrane capacitive deionization (MCDI) has emerged as a promising technology for nutrient removal and recovery. However, limitations of both scale-up and treatment of practical wastewater still restrict its real application. This study aims to investigate the feasibility of ammonia removal from real wastewater by MCDI on a pilot scale. The MCDI module used in this study was expanded to a 2-unit facility (15 pairs of electrodes per unit). Firstly, synthetic wastewater was used as feed water to optimize different kinds of operating parameters, including applied voltage (0–2.5 V), flow rate (7–30 L/h), and initial concentration (20–100 mg/L). Further experiments investigated the competitive adsorption performance under complex inflow conditions. Results indicated that the presence of co-existing cations significantly reduced the removal efficiency and adsorption capacity of ammonia. With the same inflow concentration, the removal efficiency of NH4+, Mg2+, and Ca2+ was 39.12 ± 5.31%, 47.56 ± 2.68%, and 33.33 ± 1.90% respectively. The interplay of initial ion concentration, charge valence, and hydrated radii led to the different electro-sorption performances. Subsequently, practical municipal wastewater after the up-concentration of organics was used as feed water to evaluate the feasibility of the pilot-scale MCDI. Under the optimized condition, a long-term experiment was carried out for 15-day to deal with actual wastewater. Besides, ion removal performance, the energy consumption, and desorption efficiency were also analyzed. The system maintains a stable removal efficiency for all cations, with low energy consumption (1.16 kWh/m3) and high desorption efficiency (around 90%). Overall, the results of this study posed the MCDI process as a potential approach to ammonia removal and recovery from municipal wastewater.

Rapid Removal of Mercury from Water by Novel MOF/PP Hybrid Membrane.

Mercury is one of the most toxic heavy metals that can cause terrible disease for human beings. Among different absorption materials, MOF (metal–organic framework) materials show potential as very attractive materials for the rapid removal of mercury. However, the instability and difficulty for regeneration of MOF crystals limit their applications. Here, a continuous sulfur-modified MOF (UiO-66-NHC(S)NHMe) layer was synthesized in situ on polymeric membranes (PP non-woven fabrics) by post-synthetic modification and used for rapid mercury removal. The MOF-based membrane (US-N) showed high selectivity for mercury in different aqueous systems, which is better than sulfur-modified MOF powders. A thinner MOF layer on US-N showed a much better mercury ion removal performance. US-N with a 59.3 nm MOF layer could remove more than 85% of mercury in 20 min from an aqueous solution. In addition, the US-N can simply regenerate several times for mercury removal and maintain the initial performance (removal ratio > 98%), exhibiting excellent durability and stability. This work promotes the application of MOF materials in the rapid removal of hazardous heavy metal ions from practical environments.

Enhanced desalination performance of nitrogen-doped porous carbon electrode in redox-mediated deionization

Recently, redox-mediated deionization (Redox-DI) has emerged as a promising ion separation process owing to its sustainable ion removal performance and feasibility. The characteristic cell configuration of Redox-DI involves two independent channels for treating water and supporting electrolytes containing redox couples in a multichannel system. This leads to continuous desalination mediated by a sustainable redox reaction on porous carbon electrodes, which is the preferred material in Redox-DI since it governs energy efficiency and ion removal performance. In particular, the activated carbon cloth (ACC) is a promising electrode due to its attractive features including simple shaping as a binder-free electrode and a large inter-fiber space assisting active mass transfer. However, very few studies have reported on the advancement of redox reactions on ACC electrodes, including electrocatalytic activity and rate capability. Therefore, this study aimed to produce a simple nitrogen-doped porous carbon cloth (N-ACC) electrode to improve the electrocatalytic activity for redox reactions, resulting in enhanced desalination performance of Redox-DI. The nitrogen content in N-ACC increased to approximately 3 at.% and was uniformly distributed on the surface of ACC using urea as a nitrogen source at mild temperature of 300 °C. N-ACC showed remarkable desalination performance with a salt removal rate (SRR) of 69.1 mg/g-h, a charge efficiency of 95.3%, and energy consumption of 122.0 kJ/mol. This is a 58.3% improvement in the SRR compared to ACC. In addition, through a parametric investigation with different cell voltages and flow rates, a high SRR (70–80 mg/g-h) and charge efficiency (90–100%) of N-ACC was demonstrated. N-doped ACC enhances the electrocatalytic activity, including fast reaction kinetics and low charge transfer resistance to redox couple reactions.

Reuse solution of hardness industrial circulating cooling water: Targeted ion-selective electro-adsorption by functionalized electrode

A low-cost, efficient and environmentally friendly hardness ion selective electro-adsorption system for high-hardness industrial circulating cooling water reuse was constructed to simultaneously realize a high salt removal rate and hardness ion (Ca2+ and Mg2+) selection. Multiply modified graphite carbon felt (GCF) materials for both negative and positive electrodes were proposed simply and economically, and an electro-adsorption system for hardness control was assembled. The multiple modified GCF (GCFM) materials were characterized by SEM, BET and FT-IR and the electrochemical performance was tested by CV and EIS; surface properties were studied by Zeta potential; the hardness ion removal selectivity and operational stability of the electro-adsorption system were tested. Hydrophilic functional groups were introduced in GCFM electrode, GCFM exhibited a large microporosity and demonstrated stable electrochemical performance in aqueous with a specific capacitance. The hardness ion selective electro-adsorption system achieved an adsorption capacity of 58.05 mg/g per circle for calcium ions and 31.03 mg/g for magnesium ions, indicating the superior hardness ion selectivity. In the circulating cooling water at the electro-adsorption stage, the ion removal performance was over 42.1% and maintain in good stability, GCFM electrode showed excellent deionization performance and demonstrated the application potential of hardness ion selective electro-adsorption system.

Three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles as efficient active material for high performance capacitive deionization electrodes

A three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles (3D rGO-Fe2O3) material with a suitable porous structure was synthesised using a one-step hydrothermal process in order to fabricate novel electrodes for capacitive deionization (CDI) water desalination. The morphological and structural properties of the as-synthesised compounds were characterised by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Raman spectroscopy (RS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The CDI electrodes were electrochemically analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A maximum value of specific capacitance of 345 F g−1 was achieved at 5 mV s−1 scan rate using a NaCl 0.1 mol L−1 solution. The ion removal performance of the CDI electrodes was evaluated with NaCl solutions of different concentrations, showing electrosorption capacities as high as 945 mg g−1 for 11,700 mg L−1 (200 mmol L−1) NaCl solutions, which substantially surpasses results of other carbon-based CDI electrodes.

Highly selective and antifouling reverse osmosis membrane by crosslinkers induced surface modification

ABSTRACT Post treatment is a very competent and scalable approach to develop the higher water-flux and salt-rejection membrane since it does not require any change in existing manufacturing process. The virgin Thin Film Composite Reverse Osmosis (TFC-RO) membrane was exposed to various concentrations of Poly (ethylene Glycol) diacrylate (PEGDA) and Ethylene glycol dimethacrylate (EGDMA) after activation with sodium hypochlorite for 1 h. Crosslinkers modified membranes were characterized for degree of wettability by contact angle analyses, surface morphology and surface roughness study by Scanning electron micrographs and Atomic force micrographs, chemical structural modifications by Attenuated total reflectance Fourier transform Infrared spectroscopy. These treatments resulted in improved membrane performance. 3500 mg/l PEGDA-treated membrane permeate flux increased by 48.7% and salt-rejection by 3.43%. 2000 mg/l EGDMA treated membrane demonstrated 46.13% increase in water-flux and 3.08% increase in salt-rejection as compared with virgin membrane. Organic fouling study indicated that fouling in PEGDA-treated membrane was significantly lower than virgin membrane. Heavy metal ion removal performances for Zinc and Chromium were also higher for modified membranes. Thus, the surface modification by crosslinkers led to increase in selectivity for certain metal ions and better antifouling performance as compared to virgin membrane.

Stable Forward Osmosis Nanocomposite Membrane Doped with Sulfonated Graphene Oxide@Metal-Organic Frameworks for Heavy Metal Removal.

A sulfonated graphene oxide@metal-organic framework-modified forward osmosis nanocomposite (SGO@UiO-66-TFN) membrane was developed to improve stability and heavy metal removal performance. An in situ growth method was applied to uniformly distribute UiO-66 nanomaterial with a frame structure on SGO nanosheets to form SGO@UiO-66 composite nanomaterial. This nanomaterial was then added to a polyamide layer using interfacial polymerization. The cross-linking between SGO@UiO-66 and m-phenylenediamine improved the stability of the nanomaterial in the membrane. Additionally, the water permeability was improved because of additional water channels introduced by SGO@UiO-66. SGO, with its lamellar structure, and UiO-66, with its frame structure, made the diffusion path of the solute more circuitous, which improved the heavy metal removal and salt rejection performances. Moreover, the hydrophilic layer of the SGO@UiO-66-TFN membrane could block contaminants and loosen the structure of the pollution layer, ensuring that the membrane maintained a high removal rate. The water flux and reverse solute flux of the SGO@UiO-66-TFN membrane reached 14.77 LMH and 2.95 gMH, and compared with the thin-film composite membrane, these values were increased by 41 and 64%, respectively. The membrane also demonstrated a good heavy metal ion removal performance. In 2 h, the heavy metal ion removal rate (2000 ppm Cu2+ and Pb2+) was greater than 99.4%, and in 10 h the removal rate was greater than 97.5%.

Ion removal performance and enhanced cyclic stability of SnO2/CNT composite electrode in hybrid capacitive deionization

Hybrid capacitive deionization (HCDI) is developed based on capacitive deionization (CDI) for water treatment, which combines CDI with a battery system. Developing the high-performing battery electrode materials is a significant point for HCDI. Herein, SnO2/CNT was fabricated according to hydrothermal method, which was denoted as SnO2/CNT-H, after calcination, the obtained product was denoted as SnO2/CNT-HC. The as-prepared SnO2/CNT-HC was used in HCDI system for the first time, which demonstrated a salt adsorption capacity of 9 mg g−1 and ultrafast salt adsorption rate of 2.5 mg g−1 min−1 at 500 mg L−1 initial NaCl concentration. The SnO2/CNT-HC electrode also had a good cyclic stability of keeping 120 % of salt adsorption capacity after 100 adsorption-desorption cycles at 1.0 V and 500 mg L−1 NaCl solution. Moreover, when this system was used to study the adsorption-desorption performance for different cations (Li+, K+ and Ca2+) and anions (F−, NO3− and SO42−), the phenomenon was revealed that the cation adsorption capacity of Li+ > K+ > Ca2+ captured by SnO2/CNT-HC and the anion adsorption capacity of F− > NO3− > SO42− adsorbed by activated carbon. These results show that SnO2/CNT-HC should be one of realistic electrode materials for HCDI.

Solvothermal fabrication and construction of highly photoelectrocatalytic TiO2 NTs/Bi2MoO6 heterojunction based on titanium mesh

The fabrication of TiO2 NTs/Bi2MoO6 type-II heterojunction photocatalyst was carried out by a simple solvothermal method. Bi2MoO6 nanoparticles with nanosheet microstructures were successfully loaded on TiO2 NTs surface through the adjustment of reaction intervals. The heterojunction photocatalyst showed excellent organic dye and heavy metal ion removal performances, and nearly 100%, 75%, 100% and 100% of MO, RhB, MB and Cr (VI) were removed by simulative sunlight irradiation for 3 or 2 h, respectively. The outstanding photocatalyic performance was mainly due to the formation of type-II heterojunction between TiO2 and Bi2MoO6. The type-II heterojunction not only enhanced visible light response but also accelerated photogenerated charge carrier transfer and restrained the recombination of photogenerated electron-hole pairs with the assistance of internal electric field.

Selective ion removal and antibacterial activity of silver-doped multi-walled carbon nanotube / polyphenylsulfone nanocomposite membranes

This study focuses on selective ion removal and antibacterial applications of silver-doped multiwalled carbon nanotube (MWCNT)/polyphenylsulfone (PPSU) nanocomposite membranes. The prepared Ag-doped MWCNTs are characterized according to their particle size distribution and specific surface area. Further, they are examined using transmission electron microscopy and several spectroscopic techniques; their morphology, topography, surface charge, porosity, and contact angles are reported. A performance evaluation demonstrates that the Ag-MWCNT/PPSU nanocomposite membrane exhibits unique properties and achieves optimal performance. The nanocomposite membrane exhibits significantly improved selective removal of Na2HAsO4, Na2Cr2O7, Na2SO4, NaCl, MgSO4, and MgCl2 ions from aqueous solutions compared to the pristine PPSU membrane. The antibacterial activity is evaluated using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, and is found to be enhanced by the presence of Ag-MWCNTs, which endow the nanocomposite membrane with excellent antibacterial activity. Hence, the developed Ag-MWCNT/PPSU nanocomposite membrane with improved ion removal performance and antibacterial activity could be suitable for use in potable water applications.

Perchlorate removal from brackish water by capacitive deionization: Experimental and theoretical investigations

Capacitive deionization (CDI) has attracted increasing attention over the past decade for the facile removal of ions from aqueous solutions. Nowadays, CDI is rapidly growing and evolving, and has been applied in many aspects. One important application field is water remediation, i.e., removing ionic contaminants of concern from water. Herein, we investigated the feasibility of perchlorate removal from brackish waters by batch-mode CDI technology. Effects of various operating parameters on dynamic electrosorption processes of both perchlorate and chloride were examined. Meanwhile, a one-dimensional CDI process model for dual-anions was developed to quantitatively describe the electrosorption kinetics of perchlorate and chloride, and an excellent agreement between the modeling results and the experimental data was observed. Experimental results revealed a favorably strong preferential adsorption of ClO4− over Cl− in the studied CDI system under various conditions. Moreover, only slight discrepancy between adsorption-desorption cycles was found, demonstrating the good regeneration of electrodes and operational stability of the CDI cell. Finally, the scale-up studies indicated that the CDI stack with multiple pairs of electrodes could achieve a much more superior ion removal performance than the CDI cell with only one pair of electrodes. To conclude, these results showed that the CDI system was effective for perchlorate selective removal in the presence of other major ions and had potential in treatment of perchlorate-contaminated brackish water.