Hybrid Ion Exchange Research Articles

Adsorption of Toxic Metals Using Hydrous Ferric Oxide Nanoparticles Embedded in Hybrid Ion-Exchange Resins.

Acid mine drainage (AMD) is a major environmental problem caused by the release of acidic, toxic, and sulfate-rich water from mining sites. This study aimed to develop novel adsorbents for the removal of chromium (Cr(VI)), cadmium (Cd(II)), and lead (Pb(II)) from simulated and actual AMD using hybrid ion-exchange resins embedded with hydrous ferric oxide (HFO). Two types of resins were synthesized: anionic exchange resin (HAIX-HFO) for Cr(VI) removal and cationic exchange resin (HCIX-HFO) for Cd(II) and Pb(II) removal. The resins were characterized using scanning electron microscopy and Raman spectroscopy, which confirmed the presence of HFO particles. Batch adsorption experiments were conducted under acidic and sulfate-enhanced conditions to evaluate the adsorption capacity and kinetics of the resins. It was found that both resins exhibited high adsorption efficiencies and fast adsorption rates for their respective metal ions. To explore the potential adsorption on actual AMD, HCIX-HFO demonstrated significant removal of some metal ions. The saturated HCIX-HFO resin was regenerated using NaCl, and a high amount of the adsorbed Cd(II) and Pb(II) was recovered. This study demonstrates that HFO-embedded hybrid ion-exchange resins are promising adsorbents for treating AMD contaminated with heavy metals.

Hybrid membrane distillation and ion exchange process for resources recovery from mining wastewater

This work aims to achieve a process intensification through the hybridization of direct contact membrane distillation (DCMD) and ion exchange (IX) to increase resource recovery (water, H2SO4, Copper (Cu), Nickel (Ni), and Cobalt (Co)) from a gold mining wastewater. An increase in maximum recovery rate was achieved by the DCMD in the hybrid configurations – from 34 to 52 %. Recovery of Cu, Ni and Co is best achieved by NH4OH (4 mol/L), however with considerable carryover. Conversely, selective recovery can be achieved by different eluting agents H2SO4 0.1 mol/L to recover Co (~80 %), H2SO4 1 mol/L to recover Ni (~47 %), and NH4OH 4 mol/L to recover Cu (~26 %), with a lower carryover of other ions (<14 %). Scale-up calculations showed that the Amberlyst A26 mass required for the hybrid IX (batch) is 2.4× lower than the Dowex M4195, which resulted from the exchange capacity and selectivity. Conversely, the estimated Amberlyst A26 mass required for the hybrid IX (fixed-bed) was higher due to the higher initial concentration of H₂SO₄. Lastly, CapEX ranged from 0.2 to 5.6 M US$, and OpEX from 2.61 to 11.42 US$/m3. Considering earnings with the recovered resources the hybrid fixed-bed configurations are a clear choice due to the lowest payback times (<4 years).

Hybrid ion exchange and biological processes for water and wastewater treatment: a comprehensive review of process applications and mathematical modeling

Hybrid ion exchange and biological processes for water and wastewater treatment: a comprehensive review of process applications and mathematical modeling

Accumulation mechanisms for contaminants on weak-base hybrid ion exchange resins

Mechanism of hexavalent chromium removal (Cr(VI) as CrO42-) by the weak-base ion exchange (IX) resin ResinTech® SIR-700-HP (SIR-700) from simulated groundwater is assessed in the presence of radioactive contaminants iodine-129 (as IO3-), uranium (U as uranyl UO22+), and technetium-99 (as TcO4-), and common environmental anions sulfate (SO42-) and chloride (Cl-). Batch tests using the acid sulfate form of SIR-700 demonstrated Cr(VI) and U(VI) removal exceeded 97%, except in the presence of high SO42- concentrations (536 mg/L) where Cr(VI) and U(VI) removal decreased to ≥ 80%. However, Cr(VI) removal notably improved with co-mingled U(VI) that complexes with SO42- at the protonated amine sites. These U–SO42- complexes are integral to U(VI) removal, as confirmed by the decrease in U(VI) removal (<40%) when the acid chloride form of SIR-700 was used instead. Solid phase characterization revealed that CrO42- is removed by IX with SO42- complexes and/or reduced to amorphous Cr(III)(OH)3 at secondary alcohol sites. Tc(VII)O4- and I(V)O3- also undergo chemical reduction, following a similar removal mechanism. Oxyanion removal preference is determined by the anion reduction potential (CrO42->TcO4->IO3-), geometry, and charge density. For these reasons, 39% and 69% of TcO4- and 17% and 39% of IO3- are removed in the presence and absence of Cr(VI), respectively.

Ammonia recovery from municipal wastewater using hybrid NaOH closed-loop membrane contactor and ion exchange system

Water scarcity is affected by population growth and increasing nutrients pollution. This study evaluated the integration of ion exchange-natural activated clinoptilolite zeolite (IEX-NZ) and hollow-fibre liquid–liquid membrane contactor (HF-LLMC) as an innovative and sustainable hybrid technology for ammonia recovery from treated urban wastewaters. The process is based on NaOH closed-loop process to i) ensure the extracted concentration of ammonia from the loaded zeolites and ii) enhance the transport of NH3 through the HF-LLMC. Regeneration of the IEX-NZ provided recoveries up to around 92% using 8% NaOH solution with concentration factors between 30 and 60 and a residual ammonium stream below 1 mg NH4+-N/L. Recovery of NH3 from NaOH solutions was carried out by HF-LLMCs using two different membrane chemistries: polypropylene (PP) and poly (4-methyl-1-pentene) (PMP) (>95%). A 1-D model was developed and used to describe the time evolution of NH3 concentration during the recovery process, to determine its mass transfer coefficient (9.5·107 m3/m2·s) and to quantify the undesired water co-transport (5.0·105 m3/m2·s). In addition, the model was used to analyse the influence of operational parameters on the membrane's permeability to maximise the concentration of the ammonium salts recovered as fertilisers. In this case, the 1-D algorithm was used to identify the needed stages to achieve residual levels of NH3 on the treated streams that promoted the NaOH closed-loop recycling to secure economic feasibility.

Desalination of brackish groundwater using self-regeneration hybrid ion exchange and reverse osmosis system (HSIX-RO)

The United Nations International Decade for Action on Water for Sustainable Development (2018–2028) recognized the importance of water to sustainable development and the eradication of poverty and hunger. It voiced alarm over the worsening of issues such as access to clean water, water scarcity, and wastewater as a result of increasing populations and altered climates. One of the most promising solutions to the water shortage is desalination, which can increase the available water supply beyond the currently possible limit. In this study, we analyze the performance of a unique hybrid self-regeneration ion exchange and reverse osmosis (HSIX-RO) system for the desalination of brackish groundwater. In the pretreatment step for protecting RO membrane fouling, the traditional homogenized strong acid cation exchanger (Purolite C100) and shallow shell structured strong acid cation exchanger (Purolite SSTC65) were compared for their efficiency in removing hardness cations from brackish groundwater. The fixed-bed column study concluded that C100 and SSTC65 can treat brackish water containing 250 mg L−1 Ca2+ and 10,000 mg L−1 NaCl at approximately 80 and 76 bed volumes (BVs), respectively. Studying the efficiency of RO system, it has % RO recovery of >70 % at an optimized pressure of 120 psi. An upscale self-regeneration ion exchange and RO system, i.e., HSIX-RO, that can be applied for a pilot-scale study was proposed. This proposed study suggested that HSIX-RO can be suited for the desalination of brackish groundwater with minimum use of an additional salt and can be self-sustained using an automated control. It was noted that the HSIX-RO system cannot be effectively applied to groundwater (TDS < 5000 mg L−1) nor seawater (TDS > 30,000 mg L−1) contained high Ca2+ and Mg2+ due to low regeneration efficiency and short length service runs, respectively.

Denitrification of nitrate in regeneration waste brine using hybrid cation exchanger supported nanoscale zero-valent iron with/without palladium nanoparticles

The Sustainable Development Goals require that reducing waste is a priority. This work described the application of an innovative zero-waste hybrid ion exchange nanotechnology that concurrently removed nitrate and induced denitrification to ammonia, with the ability to generate fertilizer for the agriculture sector from the recycled by-products. Herein, hybrid cation exchanger-supported zero-valent iron (Fe0), and bimetallic Fe0/Pd nanoparticles (HCIX-Fe0 and HCIX-Fe0/Pd) were synthesized and successfully validated for denitrification of nitrate in spent waste brine that contained nitrate. The kinetics of nitrate catalysis by both HCIX-Fe0 and HCIX-Fe0/Pd were compared and presented by six kinetic models, namely, zero-order, pseudo first- and second-order reaction, pseudo first- and second-order adsorption, and Elovich. HCIX-Fe0/Pd displayed a higher kinetic value than HCIX-Fe0, with k1 of 0.0019 and 0.0026 min−1, respectively. Nitrate was predominantly catalysed to NH4+ at a ratio of ammonia to other nitrogen compounds of around 80:20. Although HCIX-Fe0/Pd showed slightly better (14%) kinetic results, it was determined as unfavourable for real-life application due to low selectivity toward N2 gas and the need to use H2 gas. Based on practicability, the HCIX-Fe0 was further validated. The effect of salt (using NaCl) and the role of initial pH conditions were optimized and discussed. The recovery of nitrate removal was also calculated, and a recovery range of 91.42–99.14% was obtained for three consecutive runs. The sustainable, novel, zero waste hybrid ion exchange nanotechnology using the combination of two fixed-bed columns containing nitrate-selective resin for nitrate removal and novel HCIX-Fe0 for nitrate reduction to NH4+ may be a promising sustainable solution toward the goal of discharging zero nitrate waste to the environment.

A novel and versatile Hybrid HILIC and Ion Exchange Phase for the LC/MS Analysis of Polar Compounds

LebensmittelchemieVolume 76, Issue S2 p. S2-140-S2-140 Analytik (ATW-A) A novel and versatile Hybrid HILIC and Ion Exchange Phase for the LC/MS Analysis of Polar Compounds S.H. Liang, S.H. Liang Restek Corporation, 110 Benner Circle, Bellefonte, PA, 16823 United StatesSearch for more papers by this authorC. Flannery, C. FlannerySearch for more papers by this authorD. Li, D. LiSearch for more papers by this author S.H. Liang, S.H. Liang Restek Corporation, 110 Benner Circle, Bellefonte, PA, 16823 United StatesSearch for more papers by this authorC. Flannery, C. FlannerySearch for more papers by this authorD. Li, D. LiSearch for more papers by this author First published: 01 September 2022 https://doi.org/10.1002/lemi.202259097AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume76, IssueS2September 2022Pages S2-140-S2-140 RelatedInformation

Regeneration and modelling of a phosphorous removal and recovery hybrid ion exchange resin after long term operation with municipal wastewater

Adsorption represents one of the most promising process for phosphorous (P) removal and recovery from municipal wastewater, but questions about its long-term stability remain. The goals of this work were (i) to assess changes in morphology and adsorption performances of hybrid anion exchanger (HAIX) LayneRT after 2.5 years of operation in a 10 m3 d−1 demonstration plant fed with secondary-treated municipal wastewater, (ii) to optimize the LayneRT regeneration procedure, and (iii) to evaluate the suitability of the ion exchange model to describe P adsorption on LayneRT. LayneRT is composed of hydrated ferric nanoparticles dispersed in a strong base anion exchange resin. Batch and continuous flow adsorption/desorption tests were conducted with the resin used for 2.5 years, regenerated with two alternative solutions: NaOH, reactivating mainly the iron nanoparticles active sites, and NaOH + NaCl, also regenerating the active sites of the ion exchange media. The physicochemical characterization by Scanning Electron Microscope indicated that regeneration by NaOH significantly reduced the deterioration of the resin surface, even after 59 adsorption/desorption cycles. Lab-scale continuous flow tests showed that the resin regenerated with either solution featured P adsorption performances very close to that of the virgin resin. The isotherm tests showed that P adsorption by LayneRT was effectively simulated with the ion exchange model. This study confirms that LayneRT is a durable, resistant and promising media for P recovery from wastewater.

(Keynote) Hybrid Inorganic-Organic Ion-Exchange Membranes for Electrochemical Applications: Electrical Response and Conductivity Mechanism

Electrochemical energy conversion and storage (EECS) systems are of major interest for both industry and scientific community due to their high energy conversion efficiency and easy scalability [1]. Two families of EECS systems are attracting particular attention: ion-exchange membrane fuel cells and redox flow batteries (RFBs). On one hand, ion-exchange membrane fuel cells are particularly suited for light-duty vehicles and small-scale stationary systems (e.g., auxiliary power units) owing to their high energy and power densities. On the other hand, RFBs (with a particular reference to all-vanadium redox flow batteries, VRFBs) are ideally suited to the large-scale storage of energy for the power grid as they are characterized by a very high turnover efficiency and an outstanding cyclability.Electrolyte membranes (EMs) are found at the core of both ion-exchange membrane fuel cells and VRFBs. The role of such EMs is to: (i) keep separated the electroactive species involved in the redox reactions taking place at the electrodes and, at the same time, (ii) ensure a facile and selective migration of ions to prevent the polarization of the device and allow for the establishment of large current densities. As of today, the most widely adopted EMs for both ion-exchange membrane fuel cells and VRFBs are based on perfluorinated ionomers such as Nafion™ and other similar macromolecules [2]. These systems exhibit an outstanding proton conductivity and a very high chemical and electrochemical stability; however, they also suffer from important drawbacks such as: (i) a dramatic drop in conductivity at T > 80°C and in dry conditions; (ii) poor mechanical properties; and (iii) a large permeability to vanadium species [3, 4]. Consequently, it is often necessary to: (i) add humidification modules to ion-exchange membrane fuel cells, thus raising the bulk and cost of the device; or (ii) especially in the case of VRFBs, use thick EMs that curtail the current density.These drawbacks can be addressed by implementing several different strategies, that include: (i) the introduction of a filler in the EM, giving so rise to a hybrid inorganic-organic membrane [5]; (ii) the fabrication of the EM with a different macromolecule (e.g., a sulfonated polyaromatic system such as sulfonated polyether ether ketone, SPEEK [6]) and (iii) the doping of the EM with an ion-conducting medium (e.g., phosphoric acid [7], or a proton-conducting ionic liquid [8]). All of these strategies operate by modulating the physicochemical properties of the EMs, with a particular reference to the details of the phase segregation at the nano/mesoscale.This work overviews the study of the interplay between the physicochemical properties of hybrid ion-exchange membranes (with a particular reference to the chemical composition, thermoanalytical properties, morphology and structure), and the electrical response as determined by means of advanced investigation techniques such as Broadband Electrical Spectroscopy (BES). Results allow to: (i) elucidate the interactions between the different phases and components within each EM; and (ii) clarify the conductivity mechanism. On these bases, it is possible to identify the most promising avenues of research to devise EMs for application in ion-exchange membrane fuel cells and RFBs exhibiting a performance and a cyclability beyond the state of the art. Acknowledgement We acknowledge the support from: (a) the European Union’s Horizon 2020 research and innovation programme under grant agreement 881603; (b) the project “Advanced Low-Platinum hierarchical Electrocatalysts for low-T fuel cells” funded by EIT Raw Materials; and (c) the project “HELPER” funded by the University of Padova; and (d) the BIRD 2020 program of UNIPD.

Phosphorus removal and recovery from wastewater via hybrid ion exchange nanotechnology: a study on sustainable regeneration chemistries

Technologies that allow for removal and subsequent recovery and reuse of phosphorus from polluted streams are imperative. One such technology is hybrid ion exchange nanotechnology (HIX-Nano), which may allow to produce a valuable nutrient solution following phosphorus desorption of the saturated media. This study evaluated the potential of four regeneration chemistries to desorb phosphorus from a commercially available HIX-Nano resin hybridized with iron oxide nanoparticles using a design of experiments (DoE) approach. More sustainable and less harmful regeneration solutions using a KOH/K2SO4 blend or a recovered NH4OH alkaline solution, along with tap water instead of synthetic acid, were compared to a control solution of KOH and H2SO4. Among the four regeneration methods studied, using the combination of recovered NH4OH and tap water shows the highest phosphorus recovery potential because: (i) it involves low cost and sustainable products, (ii) it showed a relatively high recovery efficiency (75 ± 15% as compared to the control at 89 ± 13%), and (iii) it did not demonstrate any significant dampening of the resin longevity after five adsorption and desorption cycles. Based on the DoE data, a series of regression models was developed to generate understanding of the effect of important operational parameters (volume of the regenerant solution, rinse speed, strength of the alkaline solution) on the phosphorus concentration in the recovered nutrient solution. Overall, this study indicates that HIX-Nano may contribute to providing a cost-effective and sustainable technological solution to tackle the phosphorus problem in wastewater treatment applications across the globe.

(Keynote) Electrical Response and Conductivity Mechanism in Ion-Exchange Membranes

Electrochemical energy conversion and storage systems are very important in today’s worldwide efforts to decarbonize the energy sector. Indeed, these systems exhibit a very high energy conversion efficiency, are easy to scale-up and are not affected by geographical constrains [1]. Two important examples of these systems are ion-exchange membrane fuel cells (IEMFCs) and redox flow batteries (RFBs). On one hand, ion-exchange membrane fuel cells are particularly suited for light-duty vehicles and small-scale stationary systems (e.g., auxiliary power units) owing to their high energy and power densities. On the other hand, redox flow batteries are ideally suited to the large-scale storage of energy for the power grid as they are characterized by a very high turnover efficiency and an outstanding cyclability [2].Electrolyte membranes (EMs) are present at the core of both IEMFCs and RFBs. The role of such EMs is to: (i) keep separated the electroactive species involved in the redox reactions taking place at the electrodes and, at the same time, (ii) ensure a facile and selective migration of ions to prevent the polarization of the device and allow for the establishment of large current densities. As of today, the most widely adopted EMs are based on perfluorinated ionomers such as Nafion™, SPEEK and other similar macromolecules [3, 4]. These systems exhibit a high conductivity, chemical and electrochemical stability; however, they also suffer from important drawbacks such as: (i) a dramatic drop in conductivity at T > 80°C and in dry conditions; (ii) poor mechanical properties; and (iii) a high permeability to active species (e.g., vanadium) [5]. Consequently, it is often necessary to: (i) add humidification modules to ion-exchange membrane fuel cells, thus raising the bulk and cost of the device; or (ii) especially in the case of vanadium redox flow batteries (VRFBs), use thick EMs that curtail the current density.These drawbacks can be addressed by implementing several different strategies, that include: (i) the introduction of a filler in the EM, giving rise to a hybrid inorganic-organic membrane [6]; (ii) the fabrication of EMs with different macromolecules (e.g., polybenzimidazole, PBI) [6-11]. All of these strategies operate by modulating the physicochemical properties of the EMs, with a particular reference to the phase segregation at the nano/mesoscale [3]. This work overviews the study of the interplay between the physicochemical properties (i.e., the chemical composition, thermoanalytical properties, morphology and structure) and the electrical response of hybrid ion-exchange membranes by means of advanced investigation techniques such as Broadband Electrical Spectroscopy (BES).The results allow to elucidate the interplay among chemical and physical properties of the different phases within each EM and their conductivity mechanism. Indeed, the understanding of the relationship taking place between structure and ion conduction mechanisms is crucial in order to trigger the development of new high-performing proton and anion conducting membranes for applications in fuel cells and redox flow batteries.

Multifunctional ion exchange pretreatment driven by carbon dioxide for enhancing reverse osmosis recovery during impaired water reuse

Reverse osmosis (RO) has been increasingly applied for impaired water reuse in arid areas. However, enhancing RO recovery from scarce water resources is limited by energy demand for overcoming elevated brine osmotic pressure, and membrane scaling caused by concentrated poorly soluble salts. In this study, we present a hybrid ion exchange desalination process (HIX-Desal) as multifunctional RO pretreatment to enhance RO recovery by simultaneously desalinating feed water and removing multiple scale-forming ions (calcium, sulfate, and phosphate). The novelty of HIX-Desal is that carbon dioxide was the sole regenerant for a two-column train containing a hybrid anion exchanger (HAIX, with doped ferric oxide nanoparticles) and a shallow shell weak acid cation exchanger (SSWAC). We probed the desalination abilities of HIX-Desal at both lab and pilot scales using impaired water sources with varying total dissolved solids (TDS), where consistent desalination was achieved at 50–60% TDS reduction. Field tests demonstrated >80% removal of calcium, sulfate, and phosphate simultaneously. System configuration and SSWAC structure, i.e., intraparticle diffusion path length, were demonstrated to govern the HIX-Desal process during desalination and CO2 regeneration cycle. We envision this study to facilitate RO recovery enhancement and upcycling industrial carbon emission.

A Hybrid Ion-Exchange Fabric/Ceramic Membrane System to Remove As(V), Zn(II), and Turbidity from Wastewater

Ceramic membranes and ion exchangers are effective at removing turbidity and ionic contaminants from water, respectively. In this study, we demonstrate the performance of a hybrid ion-exchange fabric/ceramic membrane system to treat metal ions and turbidity at the same time in synthetic wastewater. The removal rate of As(V) and Zn(II) by the ceramic membrane increased with solution pH, while turbidity was completely removed regardless of the solution pH. The main reaction of As(V) removal was adsorption at solution pH 6 and precipitation at solution pH 8, whereas phase-change was the predominant reaction for Zn(II) removal at both solution pH values. The removal efficiency of the ion-exchange fabric was affected by the solution pH, with the maximum removal capacity of As(V) occurring at solution pH 4. The As(V) adsorption capacity of the ion-exchange fabric reached equilibrium within 120 min. The ion-exchange capacity of the ion-exchange fabric was compared with commercial ion-exchange fibers. The regeneration efficiency of the ion-exchange fabric using 0.1 M NaCl solution was around 95% on average and decreased slightly as the number of regeneration cycles was increased. Over 80% of As(V) and Zn(II) were steadily removed at solution pH 6 by the hybrid ion-exchange fabric/ceramic membrane system. Reduced flow rate and removal capacity were recovered through a backwashing process during continuous treatment with the hybrid ion-exchange fabric/ceramic membrane system.

(Keynote) Interplay between Properties, Electrical Response and Conductivity Mechanism in Hybrid Inorganic-Organic Ion-Exchange Membranes for Electrochemical Applications

Electrochemical energy conversion and storage (EECS) systems are of major interest for both industry and the scientific community owing to their potential to fulfill a major role in today’s worldwide efforts to decarbonize the energy sector. Indeed, EECS systems exhibit a very high energy conversion efficiency, are easy to scale-up and they are not affected by geographical constrains [1]. Two families of EECS are attracting particular attention owing to the complementarity of their applications, namely ion-exchange membrane fuel cells and redox flow batteries. On one hand, ion-exchange membrane fuel cells are particularly suited for light-duty vehicles and small-scale stationary systems (e.g., auxiliary power units) owing to their high energy and power densities [2]. On the other hand, redox flow batteries (with a particular reference to all-vanadium redox flow batteries, VRFBs) are ideally suited to the large-scale storage of energy for the power grid as they are characterized by a very high turnover efficiency and an outstanding cyclability [3]. Electrolyte membranes (EMs) are found at the core of both ion-exchange membrane fuel cells and VRFBs. The role of such EMs is to: (i) keep separated the electroactive species involved in the redox reactions taking place at the electrodes and, at the same time, (ii) ensure a facile and selective migration of ions to prevent the polarization of the device and allow for the establishment of large current densities. As of today, the most widely adopted EMs for both ion-exchange membrane fuel cells and VRFBs are based on perfluorinated ionomers such as Nafion™ and other similar macromolecules [3, 4]. These systems exhibit an outstanding proton conductivity and a very high chemical and electrochemical stability; however, they also suffer from important drawbacks such as: (i) a dramatic drop in conductivity at T > 80°C and in dry conditions; (ii) poor mechanical properties; and (iii) a large permeability to vanadium species [5]. Consequently, it is often necessary to: (i) add humidification modules to ion-exchange membrane fuel cells, thus raising the bulk and cost of the device; or (ii) especially in the case of VRFBs, use thick EMs that curtail the current density. These drawbacks can be addressed by implementing several different strategies, that include: (i) the introduction of a filler in the EM, giving so rise to a hybrid inorganic-organic membrane [6]; (ii) the fabrication of the EM with a different macromolecule (e.g., a sulfonated polyaromatic system such as sulfonated polyether ether ketone, SPEEK [7], or innovative anion-exchange polymers [8]); and (iii) the doping of the EM with an ion-conducting medium (e.g., phosphoric acid [9], or a proton-conducting ionic liquid [10]). All of these strategies operate by modulating the physicochemical properties of the EMs, with a particular reference to the details of the phase segregation at the nano/mesoscale [4]. This work overviews the study of the interplay between the physicochemical properties of hybrid ion-exchange membranes (with a particular reference to the chemical composition, thermoanalytical properties, morphology and structure), and the electrical response as determined by means of advanced investigation techniques such as Broadband Electrical Spectroscopy (BES). Results allow to: (i) elucidate the interactions between the different phases and components within each EM; and (ii) clarify the conductivity mechanism. On these bases, it is possible to identify the most promising avenues of research to devise EMs for application in ion-exchange membrane fuel cells and redox flow batteries exhibiting a performance and a cyclability beyond the state of the art. Acknowledgement This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 785219, and from the BIRD 2018 program of UNIPD. Figure 1

Treated Municipal Wastewater Reuse: A Holistic Approach Using Hybrid Ion Exchange (HIX) with Concurrent Nutrient Recovery and CO2 Sequestration

As freshwater supplies dwindle globally, large metropolises like Los Angeles and Singapore have made significant progress in municipal wastewater reuse where reverse osmosis (RO) is an integral com...

The impact of background wastewater constituents on the selectivity and capacity of a hybrid ion exchange resin for phosphorus removal from wastewater

Conventional sorption media are inefficient for phosphorus removal from wastewater due to preference for competing species such as sulphate, nitrate and organics. This work investigates whether the use of hybrid ion exchange resins effectively negates such concerns. Trials were conducted with a hybrid anion exchange (HAIX) media which was preloaded with different background constituents and operated over multiple regeneration cycles to ascertain the likely impacts. The work revealed that whilst the impact of the other constituents was seen in regards to direct competition, the major impact was on reduction of the rate of intraparticle mass transfer through sorption of the constituents onto the base resin thereby reducing the Donnan membrane effect. Comparison of the impact of the background water constituents on the individual components (hybrid resin, base resin, nanoparticles) revealed the importance of the nanoparticle whereby they effectively transform the ion exchange media into a mono component absorber for phosphorus that enables sustained removal even in complex wastewaters.

Evidence of Economically Sustainable Village-Scale Microenterprises for Arsenic Remediation in Developing Countries

Although unknown 25 years ago, natural arsenic contamination of groundwater affects over 50 countries and up to 200 million people. The economic viability was analyzed and modeled of eighty-eight community-based arsenic mitigation systems existing for up to 20 years in India and Bangladesh. The performances of three community-based arsenic mitigation systems that are ethnically different and separated across two different countries were monitored closely for 24 months of self-sustainable, long-term operation at WHO standards through local, paid caretakers. Based on data from the use of hybrid ion exchange materials (HIX-Nano) and the broad set of field operations, Monte Carlo simulations were used to explore the conditions required for self-sustainable operation and job creation in low-income communities (<$2/day/capita). The results from field data and cost modeling provided clear evidence of economic growth and job creation for systems managed by villagers' committee through collection of monthly tariffs. Ethnicity and religion did not have perceptible impacts on day-to-day operations or cumulative long-term revenue. The cost of the treatment technology (i.e., HIX-Nano) had minimal impact on the operational profitability, while number of customers and water delivery significantly affected profitability. Local employment generation with income significantly higher than poverty level was the most enduring outcome and led to enhanced sustainability.

Kinetics of Ion Exchange of Zr/Sn(IV) Phosphonate–Phosphate Hybrid Materials for Separation of Lanthanides from Oxidized Actinides

ABSTRACTThe kinetics of ion exchange of Zr/Sn(IV) phosphonate–phosphate hybrid ion exchange materials have been studied with several types of ions of specific interest to nuclear fuel recycling including Nd3+ at 4.5 and 43 mM and NpO2+ at 2.9 mM spanning multiple HNO3 concentrations. In most cases, the equilibrium was reached in less than 12 h. The ion exchange behavior followed that of pseudo first-order adsorption with rates ranging from 0.430–4.10 h−1 to 0.290–0.435 h−1 for Nd3+ and NpO2+, respectively. A separation with both Nd3+ and NpO2+ present was performed, resulting in separation factors of 1.9–12, 1.7–6.6, and 2.0–5.7 at 1 × 10−1, 1 × 10−2, and 1 × 10−3 M HNO3, respectively.

Hybrid Ion Exchange Desalination (HIX-Desal) of Impaired Brackish Water Using Pressurized Carbon Dioxide (CO2) as the Source of Energy and Regenerant

Reverse osmosis and electrodialysis are truly the only water desalination processes currently in practice for the entire range of total dissolved solids (TDS) from 400–40,000 mg/L. For high recovery of 80% or more, membrane processes are energy intensive even for a feedwater with a TDS of 1000 mg/L and demand significant pretreatment to avoid precipitation and consequent membrane fouling. In this study, we present for the first time a hybrid ion exchange desalination (HAIX-Desal) process that does not require any semipermeable membrane and can desalinate lean brackish water (TDS ≤ 1500 mg/L) using CO2 as the sole source of energy and chemical regenerant. A hybrid anion exchanger with dispersed ZrO2 nanoparticles (HAIX-NanoZr) and a shell–core weak-acid cation exchange (SC-WAC) resin form the heart of the process. Carbon dioxide or CO2 at 10 atm pressure is the only chemical needed to sustain the process. In contrast to a conventional deionization plant, the anion exchanger, i.e., HAIX-NanoZr, precedes the...