Anion-exchange Mode Research Articles

Ion Exchange Chromatography: A Versatile Technique for Comprehensive Characterization of Therapeutic Proteins and Peptides

Ion Exchange Chromatography (IEX) is an efficient and widely employed technique for the comprehensive characterization of therapeutic proteins and peptides. IEX separates biomolecules based on differences in their surface charge arising from amino acid composition and Post- Translational Modifications (PTMs). As a non-denaturing method, IEX is particularly valuable for resolving and quantifying charge variants like deamidation, oxidation, glycosylation, and terminal truncations in monoclonal antibodies, antibody-drug conjugates, and other biotherapeutics. The review provides insights into the principles, advantages, applications, recent advances, and limitations of using IEX (cation and anion exchange modes) for detailed analysis of proteins and peptides.

Mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) modified anion exchange membranes (AEMs) for antifouling

Mussel-inspired co-deposition has many applications in surface modification of polymer membranes. Organic fouling of ion exchange membranes is one of the common issues that hinder electrodialysis treatment of industrial wastewater. In this work, anion exchange membranes were surface-modified by the mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) nanosheets. Results showed that co-deposition with catechol (CA) and m-phenylenediamine (MPD) as reactant monomers rapidly generated modifying layer on the AEM surface. And the addition of GO into co-deposition helped improve the homogeneity and reduce polymer particle aggregation. The synergistic effect of catechol-amine and GO nanosheets was beneficial to form uniform modifying layer with improved hydrophilicity and negative charge density of membrane surface. In eletrodialysis experiments with sodium dodecyl benzene sulfonate (SDBS) as model foulants, GO-CA-MPD-3h modified AEM maintained high desalination rate close to that without folants, indicating good modifying antifouling performance. Mussel-inspired co-deposition of catecholamines and functional materials give new insights into membrane modificatin through a feasible and cost-effective method

Enhanced removal of methyl orange using modified anion exchange membrane adsorbent

Enhanced removal of methyl orange using modified anion exchange membrane adsorbent

In-situ preparation of FeCo-Layered double hydroxides modified anion exchange resin D201 for As(V) effective removal from aqueous solutions

In-situ preparation of FeCo-Layered double hydroxides modified anion exchange resin D201 for As(V) effective removal from aqueous solutions

Purification processes of live virus vaccine candidates expressed in adherent Vero cell lines via multimodal chromatography in flowthrough mode.

Live virus vaccine (LVV) purification, employing chromatography, can be challenged by low binding capacities and elution yields. Alternatively, processes relying solely on enzymatic digestion steps and size-based membrane separations can be limited by suboptimal reduction of process related impurities and poorly scalable unit operations. Here, we demonstrate that the combination of flowthrough mode chromatography and an ultrafiltration/diafiltration (UF/DF) unit operation delivers a purification process for two different LVV candidates, V590 and Measles, expressed in adherent Vero cells. For V590, chromatography with mixed mode cation exchange resins returned final product yields of ∼50% and logarithmic reduction values (LRVs) of 1.7->3.4 and 2.5-3.0 for host cell DNA (hcDNA) and host cell proteins (HCPs), respectively. For Measles, chromatography with mixed mode anion exchange resins returned final product yields of ∼50% and LRVs of 1.6 and 2.2 for hcDNA and HCPs, respectively. For both V590 and Measles processing, the employed resins cleared a key HCP, fibronectin, which could foul the UF/DF unit operation, and thusly enabling it to further reduce HCPs and to formulate the final LVV products. This integrated purification process utilizes the complementary action of the two unit operations and its applicability across LVVs supports its consideration for their processing.

Energy from Salinity Gradient of Wetland Saline Water Using Reverse Electrodialysis Membrane

Reverse electrodialysis (RED) membrane is an emerging renewable energy which harvest electricity from mixing two streams on different salinities. In real practice is still not clearly defined for the effectiveness of salinity gradient power (SGP)-RED due to the limitation of artificial saline water. Generally, South Kalimantan Indonesia is rich by wetland and coastal area. Due to that wetland saline water is potential as saline water sources for collection the SGP. This experiment aims to investigate the impact of natural feed stream wetland saline water was collected from Muara Halayung South Kalimantan-Indonesia to demineralized (WSW),artificial brackish (ABW) (0.35 wt %NaCl), and artificial seawater (ASW) (3.5 wt % NaCl) in terms of power density measured on a lab-scale RED membrane stack prototype 12 x 12 cm. Ion exchange membrane (IEM) was used in this work consisted from cellulose modified Anion Exchange Membrane (AEM) by EDTA-quaternization (EDC) process. Whereas, Cation Exchange Membrane (CEM) was employing Nafion NR-212 with thickness 0.002 in. Lab-scale RED tests operated 3 hours into area system has 121cm2; AEM and CEM area have 100cm2; uses spacer nylon a pair between membranes; and two electrodes by stainless-steal and copper. Feed water was into RED system then measured power density as an electrical energy potential that from separate ions by AEM and CEM. The result among of this experiment, characteristic of wetland saline water naturally had electro conductivity (EC) 135.6 µS/cm; TOM 15.2 ppm; and has ionic compound higher in Na+ and Cl- which is Cl- compound as one of potentially formed salinity on that wetland water and become potential uses one of natural feed water in RED system. The highest energy power density on RED process obtained by mixed WSW:ASW was 1.43 W/m2. While ratio of the gradient salinity WSW:ABW to ABW:ASW were increasing 86% which has 1:5 to 1:30 as the effect of stream mixing by two natural feed water.

Graphene oxide modified membrane for alleviated ammonia crossover and improved electricity generation in thermally regenerative batteries

Thermally regenerative batteries (TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide (GO) modified anion exchange membrane (AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result, it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.

Automated ion exchange chromatography screening combined with in silico multifactorial simulation for efficient method development and purification of biopharmaceutical targets.

Bioprocess development of increasingly challenging therapeutics and vaccines requires a commensurate level of analytical innovation to deliver critical assays across functional areas. Chromatography hyphenated to numerous choices of detection has undeniably been the preferred analytical tool in the pharmaceutical industry for decades to analyze and isolate targets (e.g., APIs, intermediates, and byproducts) from multicomponent mixtures. Among many techniques, ion exchange chromatography (IEX) is widely used for the analysis and purification of biopharmaceuticals due to its unique selectivity that delivers distinctive chromatographic profiles compared to other separation modes (e.g., RPLC, HILIC, and SFC) without denaturing protein targets upon isolation process. However, IEX method development is still considered one of the most challenging and laborious approaches due to the many variables involved such as elution mechanism (via salt, pH, or salt-mediated-pH gradients), stationary phase's properties (positively or negatively charged; strong or weak ion exchanger), buffer type and ionic strength as well as pH choices. Herein, we introduce a new framework consisting of a multicolumn IEX screening in conjunction with computer-assisted simulation for efficient method development and purification of biopharmaceuticals. The screening component integrates a total of 12 different columns and 24 mobile phases that are sequentially operated in a straightforward automated fashion for both cation and anion exchange modes (CEX and AEX, respectively). Optimal and robust operating conditions are achieved via computer-assisted simulation using readily available software (ACD Laboratories/LC Simulator), showcasing differences between experimental and simulated retention times of less than 0.5%. In addition, automated fraction collection is also incorporated into this framework, illustrating the practicality and ease of use in the context of separation, analysis, and purification of nucleotides, peptides, and proteins. Finally, we provide examples of the use of this IEX screening as a framework to identify efficient first dimension (1D) conditions that are combined with MS-friendly RPLC conditions in the second dimension (2D) for two-dimensional liquid chromatography experiments enabling purity analysis and identification of pharmaceutical targets.

Imparting antibacterial adhesion property to anion exchange membrane by constructing negatively charged functional layer

In this work, a series of modified anion exchange membranes (AEMs) has been prepared via self-polymerization of L-dopa on the surface of commercial AEM (Fuji I type), followed by grafting the 4-amino-benzenesulfonic acid monosodium salt (ABS) on L-polydopamine thin layer. The chemical structures of modified AEMs were confirmed by the FTIR and XPS spectra. Our investigation demonstrates that the surface resistance of the modified AEM (L-PDA@ABS-Cl) increases slightly from 1.90 Ω cm2 to 2.37 Ω cm2 and the hydrophilicity of L-PDA@ABS-Cl significantly improves, verifying by the decreased water contact angles from 86.42° to 67.25°. The difference between pristine AEM and L-PDA@ABS-Cl in desalination rates only remained less than 4% throughout the test of 240 min. The modified AEMs have the negatively charged functional layers which produce an electrostatic repulsion effect and negatively charged bacteria cannot attach to the membrane surface. As a result, L-PDA@ABS-Cl shows good performance on fouling resistance, good inhibition effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Low surface resistance and superior foul inhibition performance indicate the potential application of modified AEMs in electrodialysis (ED).

High sensitivity acidic N-glycan profiling with MS-enhancing derivatization and mixed mode chromatography

Acidic N-linked glycan content is often associated with a protein drug’s stability, efficacy and immune response. It has often been a challenge to analyze these types of glycans, including those that are differentiated by the incorporation of N-acetyl (NANA) and N-glycolyl neuraminic acid (NGNA) residues. In this study, a strategy for rapid N-glycan profiling by mixed mode chromatography is proposed as a complement to established HILIC methodologies. Hybrid silica chromatographic surfaces are used to improve recoveries during a column’s initial use and to eliminate the need for column conditioning. In addition, the loss of labeled acidic glycans, especially phosphorylated glycan species, during SPE purification is addressed through the use of a citrate containing eluent. Yields for both singly and doubly phosphorylated glycan species are markedly improved. Combined with a mixed mode anion exchange reversed phase separation, these advances afford a class separation of glycans derivatized with labels designed to enhance positive ion mode MS detection. These labeled glycan species are separated according to their charge and with an added level of resolution imparted by the reversed phase retention mechanism. The separation technique itself can be accomplished with a low ionic strength gradient running from 0 to 22 mM ammonium formate such that high sensitivity detection can be achieved by both fluorescence and mass spectrometry. Using analytical scale chromatography, features in an N-glycan profile were easily interrogated to well below a 0.1% relative abundance. As such, it became possible to characterize N-glycans from recombinant beta glucuronidase and to quickly identify a number of unique phosphorylated glycan species.

In-Situ Preparation of Feco-Layered Double Hydroxides Modified Anion Exchange Resin D201 for As(V) Effective Removal from Aqueous Solutions

In-Situ Preparation of Feco-Layered Double Hydroxides Modified Anion Exchange Resin D201 for As(V) Effective Removal from Aqueous Solutions

Preparation and characterization of modified anion exchange resin for uranium adsorption: estimation of nonlinear optimum isotherm, kinetic model parameters, error function analysis and thermodynamic studies

In this study, a modified metal hydroxides on surface of Lewatit resin (HMO @LM500, where M indicates to Al, Fe, Mn or Zn) were designed and used as efficient adsorbents for uranium (U(VI)) ions capture from aqueous solution. The prepared materials were characterized by using transform infrared spectroscopy, scanning electron microscope, energetic dispersive x-ray techniques. Batch adsorption methods were done to investigate all factors affecting adsorption process such as the effect of pH, concentration, contact time and temperature. Optimum values of each parameter were calculated as pH of 1.8, temperature of 298 K (25 °C), contact time of 60 min for the removal of uranium ions. Analysis within the nonlinear isotherm models indicates that the Liu model offers the best description for the equilibrium data since it has the highest R 2 value and the lowest error analysis value when compared with the other models. The calculated adsorption capacity of Liu model is 217.06 mg g−1, whereas analysis within the nonlinear kinetic models indicate that pseudo-second-order behavior is involved. The thermodynamic examination of the equilibrium data proved that the adsorption process of U(VI) was found to be a spontaneous and exothermic process. The ΔH 0 and ΔS 0 parameters were calculated as −66.5827 kJ mol−1 and −0.2051 kJ mol−1 K−1, respectively. Therefore, the prepared adsorbent can be applied to capture of U(VI) ions from aqueous medium.

(Invited) Tuning Triblock Co-Polymer Silver Interactions on the Nanoscale to Enhance Transport in Electrodes for Electrochemical Devices Based on Anion Exchange Membranes

Anion exchange membranes (AEMs) have recently attracted interest for applications in fuel cells, electrolyzers, redox flow batteries, reverse electrodialysis, and water purification. In contrast to proton exchange membranes (PEMs), AEMs operate in base instead of acid and facilitate the transport of anionic species. In fuel cells and electrolyzers, this allows for more facile kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) respectively. Therefore, AEM-based devices provide the opportunity to utilize non-precious metal catalysts to achieve similar performance to Pt-based catalysts and a substantially reduced cost. The electrodes of these devices are comprised of a heterogeneous mixture of conductive carbon support, catalyst particles, and ionomer, which form a triple-phase boundary where the electrochemical reactions take place. The ionomer is an alkaline polymer electrolyte similar to the AEM which transports OH- and water to/from the catalyst surface and promotes reactant transport.The electrode layers in PEM-based fuel cells were developed empirically, and it was not until recently that research efforts were dedicated to investigating the heterogeneous microstructure and triple-phase boundary that form. Currently, the catalyst layer as it exists in an operating device is not well understood due to its complex nature; however, model interfaces between ionomers and catalyst particles have been used to provide valuable insight on ionomer-catalyst interfacial interactions. It is known from studies with Nafion® that restructuring of the polymer morphology can occur when it exists as an ionomer thin film at a catalyst interface. The behavior of the thin film ionomer changes compared to its bulk characteristics, which ultimately affects electrode kinetics by altering the nature of its microstructure, leading to shifts in morphology, water uptake properties, and ionic and water transport networks.Initial work was driven by the overarching hypothesis that the polymer-catalyst interfacial interactions could be modified by changing the ionomer chemistry. This was investigated by studying interactions between silver nanoparticles and anion exchange ionomers functionalized with two different quaternary ammonium cations, using our previously reported block copolymer backbone polychloromethylstyrene-b-polycyclooctene-b-polychloromethylstyrene (PCMS-b-PCOE-b-PCMS) functionalized with either trimethylammonium (TMA) or methylpiperidinium (MPRD) quaternary ammonium cations. Our early findings indicated there were interactions between silver nanoparticles and C=C groups in the polycyclooctene midblock of the polymer backbone. This motivated the development of a modified anion exchange polymer by hydrogenating the PCOE midblock in PCMS-b-PCOE-b-PCMS to synthesize a polyethylene (PE) midblock. Hydrogenation was achieved through a reaction with p-toluenesulfonyl hydrazide. The improved characteristics of the PE-based membrane have prompted studies investigating the comparison of saturated and unsaturated ionomers.A uniquely tunable polymer system was developed which has enabled further investigations of ionomer thin films on silver substrates. The thin film geometry allows for the use of grazing incidence small angle x-ray scattering (GISAXS) and atomic force microscopy (AFM) to study the interfacial morphology as a function of ionomer chemistry. Restructuring of the polymer morphology compared to its bulk properties has been confirmed, and our initial findings on the contribution of different cationic moieties will be discussed in the results of this report.

Separation of Rare Earth Elements (REE) by Ion Interaction Chromatography (IIC) Using Diglycolic Acid (ODA) as a Complexing Agent

The possibility of rare earth elements (REE) separation by ion interaction chromatography (IIC) employing their complexes with diglycolic acid (ODA) in anion exchange mode has been studied theoretically and experimentally. Calculations, assuming that only trivalent complex is significantly uptaken by the stationary phase, indicated that at at pH 4–6, the retention in the lanthanide series should increase from La to the Tb–Dy–Ho region with yttrium showing apparent atomic number (App.At.No.) of 67½ and then decrease with further increase of atomic number. Chromatographic experiments in the system: Column: Eternity C18—mobile phase 5 mM ODA/8.6 mM TBAOH/0.6 mM HNO3; pH 4.60 confirmed theoretically predictions. It was found that scandium at pH ≥ 4.0 elutes in front of the whole REE group but at low pH enters the region of light lanthanides. The non-monotonical change of affinity of the REE with the increase of atomic number results in quite unusual order of elution of REE namely: Sc < La < Ce < Lu < Pr < Yb < Nd < Tm < Sm < Eu < Er≈Y < Gd < Ho < Tb≈Dy.

Anion assisted extraction of U(VI) in alkylammonium ionic liquid: Experimental and DFT studies

The extraordinary extraction of metal ions in imidazolium ionic liquid phase containing neutral extractants was most often attributed to the cation exchange mechanism in addition to the usual solvation-type mechanism. The cation exchange mechanism results in an irreversible loss of the ionic liquid cation, which eventually leads to the pollution of aqueous phase also. To minimize the limitations of imidazolium based ionic liquid, strongly hydrophobic ionic liquids containing tetra-alkyl ammonium ion have been introduced and studied for actinide separation. Even though these tetra-alkyl ammonium ionic liquids did not undergo cation exchange, but showed exceptional extraction of actinides for the reason, which was not established so far. To unravel the unique role of these hydrophobic ionic liquids, the extraction behavior of U(VI) was studied in a solution of tri-n-octylmethylammonium nitrate ([N1888 ][NO3]) in conjunction with a neutral ligand, 2-hydroxy-N,N-dioctyl acetamide (DOHyA). The extraction of U(VI) was studied as a function of various extraction parameters and the organic phase obtained after extraction was probed by FTIR and Raman spectroscopy to elucidate the mechanism of U(VI) extraction in ionic liquid phase. The result revealed that U(VI) was extracted into ionic liquid phase by a couple of extraction modes, namely through metal–ligand coordination and by loss-less anion exchange mode and these pathways did not cause any undue burden to the organic and aqueous phases, unlike the traditional imidazolium ionic liquids. Further, DFT studies were performed to elucidate the underlying mechanism of U(VI) complexation in ionic liquid phase. The calculated values of binding energy (ΔE) and Gibbs free energy (ΔG) for the complexation of U(VI) with DOHyA in dodecane and tetra-alkyl ammonium ionic liquids medium were found in good agreement with the experimentally determined complexation trends of U(VI) ion with DoHyA. The DFT calculations further established that the cation exchange mechanism by both the ionic liquids, [N1888][NO3] and [N1888][NTf2] was not feasible, but anion exchange mechanism could be possible as observed in the experimental studies.

Measurement of bempedoic acid and its keto metabolite in human plasma and urine using solid phase extraction and electrospray LC-MS/MS

Bempedoic acid, a new therapeutic for treatment of hypercholesterolemia, inhibits hepatic ATP-citrate lyase in the cholesterol synthesis pathway after its conjugation with coenzyme A. Sensitive and selective methods were required to study the pharmacokinetic behavior of bempedoic acid and its active 8-keto metabolite in clinical studies. A mixed mode anion exchange extraction on 96-well plates was developed to favor high, selective recoveries of these dicarboxylic acids from urine or plasma. Adsorptive losses in urine led to inaccurate measurements unless samples were acidified and diluted with isopropanol prior to any specimen transfers. Tandem mass spectrometry with negative ion electrospray ionization permitted lower limits of measurement of 20 and 10 ng/mL for the drug and metabolite in either matrix. The methods were validated to current regulatory standards and have been the basis for pharmacokinetic measurements in 26 clinical studies involving over 15,000 samples.

Poly(ethyleneimine) embedded octadecyl based stationary phase for multimodal chromatographic separation

In present research, a novel poly(ethyleneimine) (PEI) inserted octadecyl based phase named as Sil–PEI–STA was prepared for liquid chromatographic separation. Several approaches including elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy as well as scanning electron microscopy were chosen to characterize the prepared materials. Then, polycyclic aromatic hydrocarbons (PAHs), alkylbenzenes and positional isomers were analyzed as analytes for evaluating reversed phase chromatographic mode of the developed Sil–PEI–STA column. Interestingly, the column showed excellent properties for the separation of isomers. In addition, classical hydrophilic compounds (nucleosides and nucleobases) were selected to assess the hydrophilic selectivity of Sil–PEI–STA column. Moreover, anion exchange mode was evaluated by separating the mixture of benzoic acids. The Sil–PEI–STA column was further utilized for the separation of flavonoids and anilines compounds. The prepared column showed better separation for various compounds compared with the commercial C18 and NH2 columns under certain chromatographic conditions. In summary, the Sil–PEI–STA column provided flexible selectivity and better separation efficiency for hydrophobic, hydrophilic and charged compounds than commercial HPLC columns in certain conditions.

Imidazolium ionic liquid-enhanced poly(quinine)-modified silica as a new multi-mode chromatographic stationary phase for separation of achiral and chiral compounds

In this work, a novel imidazolium ionic liquid-functionalized poly(quinine)-modified silica stationary phase (Sil-PQn-MIm) was successfully synthesized via surface radical chain transfer and nucleophilic substitution reaction. The modified silica was confirmed by series of characterizations including Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The multi-mode chromatographic performances of the Sil-PQn-MIm column were investigated by anion-exchange mode for separation of aromatic acid samples, hydrophilic interaction mode for separation of nucleosides/nucleobases and sulfanilamides, and reversed-phase mode for separation of alkylbenzenes, benzene and polycyclic aromatic hydrocarbons (PAHs), and the Tanaka test mixtures, respectively. As expected, compared to the Sil-PQn column only with quinine as functional group, the Sil-PQn-MIm column further modified by imidazolium ionic liquid possessed higher separation performance, especially for the separation of nucleosides/nucleobases. The effects including buffer concentration, pH, organic solvent content and column temperature on chromatographic performance were studied, which proved that multiple interactions including electrostatic, hydrophobic and hydrophilic interactions can be simultaneously existed between the stationary phase and the analytes. In addition, reproducibility and efficiency of the Sil-PQn-MIm column were also investigated, the results illustrated that the stationary phase have good enough reproducibility (RSDs 0.15%–0.72%, n = 7) and high efficiency (plates per meter, ~90000 plates/m). In conclusion, the prepared stationary phase with multiple-mode retention capabilities could realize separation for various types of samples by optimizing chromatographic conditions, even for some chiral compounds.

Co-monomer polymer anion exchange resin for removing Cr(VI) contaminants: Adsorption kinetics, mechanism and performance

Modified anion exchange resin (EDE-D301) was synthesized by mixing monomers: epichlorohydrin (ECH), dimethylamine (DMA), ethylenediamine (EDA) with the weakly alkaline anion exchange resin D301 through in-situ polymerization method. Adsorption performance of EDE-D301 for removing Cr(VI) contaminants was investigated in batch and column systems. Physicochemical properties of the anion exchange resins were characterized to determine the adsorption mechanism and regeneration ability. Characteristic results revealed that EDE-D301 showed enhanced surface area, positive charge and contents of N and Cl elements, indicating that the modifying reagents of monomers were successfully polymerized in the resin. The experimental adsorption data fitted well to the pseudo-second-order kinetic model and the Langmuir isotherm model. The fixed-bed experiments showed that the exhaustion time increased with increasing the bed depth, and decreased with increasing the flowrate and influent concentration. Adsorption capacity for Cr(VI) onto EDE-D301 was determined at a maximum level of 298 mg·g−1, and remained at 93% after four consecutive cycles. FTIR and XPS analysis indicated that the ion exchange and complexation were responsible for the Cr(VI) adsorption.

Custom-Made Ion Exchange Membranes at Laboratory Scale for Reverse Electrodialysis.

Salinity gradient power is a renewable, non-intermittent, and neutral carbon energy source. Reverse electrodialysis is one of the most efficient and mature techniques that can harvest this energy from natural estuaries produced by the mixture of seawater and river water. For this, the development of cheap and suitable ion-exchange membranes is crucial for a harvest profitability energy from salinity gradients. In this work, both anion-exchange membrane and cation-exchange membrane based on poly(epichlorohydrin) and polyvinyl chloride, respectively, were synthesized at a laboratory scale (255 2) by way of a solvent evaporation technique. Anion-exchange membrane was surface modified with poly(ethylenimine) and glutaraldehyde, while cellulose acetate was used for the cation exchange membrane structural modification. Modified cation-exchange membrane showed an increase in surface hydrophilicity, ion transportation and permselectivity. Structural modification on the cation-exchange membrane was evidenced by scanning electron microscopy. For the modified anion exchange membrane, a decrease in swelling degree and an increase in both the ion exchange capacity and the fixed charge density suggests an improved performance over the unmodified membrane. Finally, the results obtained in both modified membranes suggest that an enhanced performance in blue energy generation can be expected from these membranes using the reverse electrodialysis technique.