Anion Exchange Research Articles

Cholestyramine in hemodialysis: a new approach for hyperphosphatemia management.

Hyperphosphatemia is a potentially life altering condition in end-stage renal disease patients who are on regular hemodialysis that can lead to cardiovascular calcification, metabolic bone disease and secondary hyperparathyroidism. Bile acid sequestrants are anion exchange resins bind to bile acids and phosphate in the intestine resulting in preventing intestinal absorption of dietary phosphate, interruption of bile acid homeostasis and reduction in low-density lipoprotein cholesterol levels. Cholestyramine is chosen for study in hemodialysis patients based on the effectiveness and safety of bile acid sequestrants such colestilan and colestipol in the treatment of hyperphosphatemia and hypercholesterolemia in hemodialysis patients. A prospective, interventional, randomized, double blinded, placebo-controlled two arm study was carried out to assess the efficacy of oral cholestyramine on reduction of serum phosphate level in adult hemodialysis patients. 76 eligible patients were randomly assigned to either a drug group or a placebo group for the 2-month study period. The protocol was approved by the institutional review board of the faculty of pharmacy Ain Shams University Ethical committee and has been registered on ClinicalTrials.gov: NCT05577507. Over the 2-month treatment period, patients in cholestyramine group showed a significant decline in serum phosphorus levels versus placebo group (4.6 mg/dl vs. 6.6 mg/dl; p < 0.001) and serum calcium-phosphorus product (40 mg2/dl2 vs. 59.8 mg2/dl2; p < 0.001). Median serum triglyceride and low-density lipoprotein cholesterol levels had decreased significantly versus baseline values in the cholestyramine group. Cholestyramine used with phosphate binders effectively lowers phosphorus levels, improves the lipid profile, and has mild adverse effects.

Asymmetric Electrode Ionomers Based on Polydiallyldimethylammonium Block Copolymers for Enhanced Performance in Anion Exchange Membrane Fuel Cells

Abstract Fuel cells offer a promising solution for clean energy conversion, with anion exchange membrane fuel cells (AEMFCs) being particularly attractive for their potential to use less expensive, non-platinum group metal (non-PGM) catalysts. Despite significant progress in AEMFCs in recent years, their performance is limited by instability often resulting from water imbalance within the cell (e.g, anode flooding, cathode dry-out). Implementing asymmetric electrode anion exchange ionomers (AEIs), i.e., using a hydrophobic AEI at the anode to inhibit swelling and a hydrophilic AEI at the cathode to prevent water depletion, could overcome issues of poor water management. In this study, block copolymer (BCP) AEIs of polydiallyldimethylammonium hydroxide-block-polystyrene (PDADMAOH-b-PS) were synthesized via reversible addition-fragmentation chain transfer polymerization, achieving ion exchange capacities of 1.03 to 3.40 mmol/g. These BCP AEIs were employed in the AEMFCs to optimize water distribution by controlling the hydrophobicity/hydrophilicity of the gas diffusion layers. Our results demonstrated lower ohmic losses and mass transport limitations in the asymmetric electrode design versus the symmetric analog.

Performance Evaluation of Poly(Vinylidene Fluoride)- Vinyl Benzyl Trimethyl Ammonium Chloride Copolymer as Anion Exchange Membranes for Fuel Cell Applications

Performance Evaluation of Poly(Vinylidene Fluoride)- Vinyl Benzyl Trimethyl Ammonium Chloride Copolymer as Anion Exchange Membranes for Fuel Cell Applications

Facile Electrode Manufacturing Strategy for Ultra-Low Cobalt Consumption in Oxygen Evolution Reaction

Water splitting is a sustainable method of hydrogen production that is crucial for achieving carbon neutrality. However, the high cost of green hydrogen remains a major challenge. One strategy to reduce costs is the use of non-precious metal catalysts, such as Co, which is known for its excellent catalytic properties. However, the limited supply and increasing cost of Co pose challenges. In this study, we developed a method to significantly reduce Co usage in catalyst-coated substrates for anion exchange membrane water electrolysis. By incorporating a Co solution into the slurry during a printing transfer method with NiFe oxide, we achieved a 72-fold reduction in Co consumption while improving the overpotential by 12.9% (380 mV at 100 mA cm&lt;sup&gt;-2&lt;/sup&gt;). In single-cell anion exchange membrane water electrolysis tests, the catalyst-coated substrate electrode delivered a current density of 900 mA cm&lt;sup&gt;-2&lt;/sup&gt; at 1.8 V&lt;sub&gt;cell&lt;/sub&gt;, outperforming NiFe oxide electrodes (630 mA cm&lt;sup&gt;-2&lt;/sup&gt;). This strategy demonstrates a broadly applicable approach for reducing the use of expensive elements in green hydrogen production.

Performance Trade-Off in Nickel-Based Hydrogen Evolution Catalysts for Anion Exchange Membrane Water Electrolysis: Effects of the Nickel Oxidation State and Particle Size

The development of green hydrogen through anion exchange membrane water electrolysis (AEMWE) is essential for achieving carbon neutrality. Developing non-precious-metal catalysts for the hydrogen evolution reaction (HER) is crucial for the commercialization of AEMWE. In this study, Ni-CeO&lt;sub&gt;2&lt;/sub&gt;/C catalysts were synthesized via a co-precipitation method and a reduction heat treatment was conducted from 300 to 500 &lt;sup&gt;o&lt;/sup&gt;C to form metallic Ni for the HER. Through this process, CeO&lt;sub&gt;2&lt;/sub&gt; nanoparticles were uniformly dispersed around Ni metal nanoparticles. Among these catalysts, Ni-CeO&lt;sub&gt;2&lt;/sub&gt;/C 400 exhibited a prominent Ni&lt;sup&gt;0&lt;/sup&gt; peak according to an XPS analysis and formed smaller nanoparticles compared to Ni-CeO&lt;sub&gt;2&lt;/sub&gt;/C 500, yielding advantageous physicochemical properties for the HER. Subsequently, an electrochemical half-cell LSV analysis demonstrated the lowest HER overpotential of 164 mV at 10 mA cm&lt;sup&gt;-2&lt;/sup&gt; and a Tafel slope of 89 mV dec&lt;sup&gt;-1&lt;/sup&gt;, suggesting the formation of a trade-off point in the HER performance due to variations in the oxidation state and particle size of the Ni metal. Furthermore, a non-precious-metal-based AEMWE single cell with Ni-CeO&lt;sub&gt;2&lt;/sub&gt;/C 400 as the cathode and Co&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; as the anode achieved a current density of approximately 700 mA cm&lt;sup&gt;-2&lt;/sup&gt; at 2.0 V&lt;sub&gt;cell&lt;/sub&gt;. It also exhibited stable durability at a constant current of 500 mA cm&lt;sup&gt;-2&lt;/sup&gt; for 100 hours, suggesting the potential for long-term hydrogen production in non-precious-metal-based AEMWE systems.

Dominant Role of Coexisting Ruthenium Nanoclusters Over Single Atoms to Enhance Alkaline Hydrogen Evolution Reaction.

Developing efficient and cost-effective electrocatalysts to replace expensive carbon-supported platinum nanoparticles for the alkaline hydrogen evolution reaction remains an important challenge. Recently, an innovative catalyst, composed of ruthenium single atoms (Ru1) integrated with small Ru nanoclusters (RuNC), has attracted considerable attention from the scientific community. However, because of its complexity, this catalyst remains a topic of some debate. Here, a method is reported of precisely controlling the ratios of Ru1 to RuNC on a nitrogenated carbon (NC)-based porous organic framework to produce Ru/NC catalysts, by using different amounts (0, 5, 10 wt.%) of reducing agent. The Ru/NC-10 catalyst, formed with 10 wt.% reducing agent, delivered the best performance under alkaline conditions, indicating that RuNC played a significant role in actual alkaline hydrogen evolution reaction (HER). An anion exchange membrane water electrolyzer (AEMWE) system using the Ru/NC-10 catalyst required a significantly lower operating voltage (1.72V) than the commercial Pt/C catalyst (1.95V) to achieve 500mA cm-2. Moreover, the system can be operated at 100mA cm-2 without notable performance decay for over 180h. Theoretical calculations supported these experimental findings that Ru1 contributed to the water dissociation process, while RuNC is more actively associated with the hydrogen recombination process.

Binary Phase Diagrams of Coordination Polymers with Eutectic Behaviors.

We demonstrated the construction of binary phase diagrams of coordination polymer crystals by using their reversible solid-liquid transition (melting and crystallization) behaviors. Three types of binary phase diagrams of Ag+-based coordination polymers were made and the origins of each diagram formation were investigated. All diagrams showed eutectic phenomena induced by ligand exchange reactions at the interface of the two constituents. Solid solution formation was observed when we used two crystals with similar structures and coordination geometries, and the reaction was driven by both the anion and ligand exchange processes. The optimal binary compounds found in the phase diagrams were applicable as a latent heat storage material working at 100 °C with high energy recovery efficiency, stability in phase-transition cycles, and large hysteresis of melting/crystallization.

A Simple and Efficient Non-Noble Cathode Catalyst Based on Carbon Hollow Nanocapsules Containing Cobalt-Based Materials for Anion Exchange Membrane Water Electrolyzer.

An efficient approach for fabrication of non-noble metal-based electrocatalyst is desirable fordesigning the energy storage and conversion devices in real-world usages due to low cost and excellent catalytic properties. The preparation of hollow carbon capsules (HCC) containing cobalt (Co)-based electrocatalyst is reported by a simple synthesis process without using templates for the first time. Initially, cobalt phenylphosphonate (Co-MOF) nanorods are fabricated through a simple hydrothermal approach. The as-formed Co-MOF is covered with a thin coating of polydopamine (DP-Co-MOF) through chemical polymerization of dopamine in Tris-HCl (pH 8.5). The DP-Co-MOF is used as self-degraded template for the formation of HCC under pyrolysis. The formation mechanism and hydrogen evolution reaction (HER) activity of HCC are investigated. The hollow structure derived under N2exhibits a low overpotential (295mV at 100mA cm-2) with excellent stability (90.98%) for 150h, whichis further verified by density functional theory (DFT) calculations. Finally, the designed anion exchange membrane (AEM) water electrolyzer based on C─Co─N as cathode delivers a current density of 500mA cm-2(at 2.19V) and 1000 mAcm-2 (at 2.33V)in 1.0m KOH at 60°C. The fabricated new Co-based electrocatalyst is highly beneficial for the fabrication of cost-effective and high-performance AEMWEs.

MXene-Assisted NiFe sulfides for high-performance anion exchange membrane seawater electrolysis

Anion exchange membrane seawater electrolysis is vital for future large-scale green hydrogen production, however enduring a huge challenge that lacks high-stable oxygen evolution reaction electrocatalysts. Herein, we report a robust OER electrocatalyst for AEMSE by integrating MXene (Ti3C2) with NiFe sulfides ((Ni,Fe)S2@Ti3C2). The strong interaction between (Ni,Fe)S2 and Ti3C2 induces electron distribution to trigger lattice oxygen mechanism, improving the intrinsic activity, and particularly prohibits the dissolution of Fe species during OER process via the Ti-O-Fe bonding effectively, achieving notable stability. Furthermore, the good retention of sulfates and the abundant groups of Ti3C2 provide effective Cl- resistance. Accordingly, (Ni,Fe)S2@Ti3C2 achieves high OER activity (1.598 V@2 A cm-2) and long-term durability (1000 h) in seawater system. Furthermore, AEMSE with industrial current density (0.5 A cm-2) and durability (500 h) is achieved by (Ni,Fe)S2@Ti3C2 anode and Raney Ni cathode with electrolysis efficiency of 70% and energy consumption of 48.4 kWh kg-1 H2.

Self‐Supported Ni/Ni(OH)2 Electrodes for High‐Performance Alkaline and AEM Water Electrolysis

AbstractA novel tape‐cast Ni/Ni(OH)2 electrode is developed for water electrolysis applications. Through precise control of sintering temperature and in situ formation of Ni(OH)2 nanosheets, the electrode achieves an optimized hierarchical porous structure with interconnected channels, facilitating efficient gas bubble transport and release. The electrode exhibits remarkable hydrogen evolution reaction activity with overpotentials of 40 and 124 mV at 10 and 100 mA cm−2, respectively, comparable to noble metal catalysts. The unique microstructure enables rapid bubble detachment and enhanced mass transport, leading to a high current density of 0.91 A cm−2 at 1.8 V in alkaline water electrolysis. The inherent Ni/Ni(OH)2 composition demonstrates excellent stability over 1500 h of continuous operation and maintains consistent performance under intermittent conditions, making it particularly suitable for renewable energy integration. For anion exchange membrane water electrolysis, the electrode's smooth surface morphology prevents membrane damage while maintaining efficient mass transport, delivering 0.4 A cm−2 at 1.8 V. This study demonstrates that rational design of electrode microstructure through tape‐casting offers a promising pathway toward high‐performance, durable, and cost‐effective water electrolyzers.

Charge Transfer at the Interface of Iridium and Atomically Dispersed Mn-O Clusters Induced Full-Potential Hydrogen Oxidation.

Hydrogen has long been an important energy source for sustainable development, and platinum group metals (PGMs) are the prominent anode catalysts for anion exchange membrane fuel cells (AEMFCs). However, among the PGM catalysts used in alkaline hydrogen oxidation reaction (HOR) for the AEMFC anode, the activity of iridium decreases sharply when the reaction potential exceeds 0.2 V vs reversible hydrogen electrode (RHE) due to the reduction of hydrogen adsorption (Had), which is caused by the overadsorption of OH. Herein, we prepared Ir nanoparticles with atomically dispersed Mn-O clusters on their surface (Ir/Mn0.40OC), the difference in the work function drives the charge transfer from Mn-O clusters to Ir at full HOR potential (∼0-1.2 V vs RHE), which could upshift its d-band center to enhance Had. This strategy realized HOR at full potential and the 5 h durability test only lost about 10.9% current density at 0.71 V vs RHE. Moreover, this catalyst could be used in the AEMFC anode and the mass-normalized activity of the anode reaches 8.26 W mgIr-1.

New Standardized Procedure to Extract Glyphosate and Aminomethylphosphonic Acid from Different Matrices: A Kit for HPLC-UV Detection

Background: Glyphosate has been extensively used as herbicide since the early 1970s. The daily exposure limit is set at 0.3 mg/kg bw/d in Europe and 1.75 mg/kg bw/d in the USA. Among its derivatives, aminomethylphosphonic acid is the most stable and abundant. Understanding their biological effects then requires reliable methods for quantification in biological samples. Methods: We developed and validated a fast, low-cost, and reliable chromatographic method for determining glyphosate and aminomethylphosphonic acid concentrations. The validation included following parameters: specificity, selectivity, matrix effect, accuracy, precision, calibration performance, limit of quantification, recovery, and stability. Sample extraction employed an anion exchange resin with elution using hydrochloric acid 50.0 mmol/L. For HPLC analysis, analytes were derivatized, separated on a C18 column with a mobile phase of phosphate buffer (0.20 mol/L, pH 3.0) and acetonitrile (85:15), and detected at 240 nm. Results: The method demonstrated high reliability and reproducibility across various matrices. Its performance met all validation criteria, confirming its suitability for quantifying glyphosate and aminomethylphosphonic acid in different biological and experimental setups. Conclusions: This method can offer a practical resource for applications in experimental research, medical diagnostics, quality control, and food safety.

Interstitial Manganese-Tuned Nickel-Iron Diselenide Anode for Efficient and Durable Anion Exchange Membrane Water Electrolysis.

Anion exchange membrane water electrolysis (AEMWE) employing Ir/Ru-free anodes emerges as a bright prospect for green hydrogen society. Here, a Ni0.8Fe0.2Mn0.1Se2 nanosheet electrocatalyst is reported, in situ grown on stainless-steel paper, as an efficient and durable self-supporting AEMWE anode for oxygen evolution reaction (OER). The interstitial [MnSe4] tetrahedra elevate the Fermi level and narrows the band gap of the electrocatalyst, thereby expediting electrode reaction kinetics and increasing the electrical conductivity. In addition, the interstitial Mn atoms attenuate the electron density of Ni and Fe and motivate phase transition to actual active (Mn, Fe)-doped γ-NiOOH species. The downward d-band center of Ni active center facilitates the rate-limiting *OOH desorption step, refreshing the active center, and reducing the free energy barriers for OER. Accordingly, the Ni0.8Fe0.2Mn0.1Se2 electrode achieves OER overpotentials of 149 and 232mV at 10 and 100mA cm-2 in 1m KOH. The AEMWE cell incorporating Ni0.8Fe0.2Mn0.1Se2 anode demonstrates high performance (1.0Acm-2 at 1.68 Vcell) and durability (at 1Acm-2 for 300h), surpassing most AEMWE cells that use NiFe-based anodes. This work highlights the potential of noble-metal-free anodes for efficient and durable AEMWE.

Ce/LDHs coating modified by GO applied on AZ31 alloys corrosion protection

Layered double hydroxides (LDHs) exhibit anion exchange properties and adjustable characteristics, which make them suitable for applications in the field of anticorrosion. However, the smooth growth pattern of a single LDHs nanosheet limits its effectiveness in blocking corrosive media. Graphene oxide (GO) has a large specific surface area and numerous oxygen-containing functional groups on its surface, which can form strong interactions with polar molecules. This inhibits the migration of small ions, such as Cl−. In this work, Ce was incorporated into a micro-arc oxidation (MAO) coating on the AZ31 alloy by immersion in a cerium salt solution, and GO was incorporated using a hydrothermal solution to prepare layered double hydroxide composite coating (Ce/LDHs-G). The significance of charge transfer resistance ( Rct) mainly reflects the charge transfer process at the electrode/electrolyte interface. The Rct of Ce/LDHs-G increased by one order of magnitude compared to MAO coating. The corrosion current density ( icorr) of Ce/LDHs-G coating was 3.73 × 10−8 A cm−2, lower than that of MAO coating (1.56 × 10−6 A cm−2). Additionally, the cumulative hydrogen evolution over 336 h was lower, indicating that Ce/LDHs-G coating provides effective corrosion protection for the AZ31 alloy.

Assessing the potential of activated carbon and anion-exchange in combination to remove organic micropollutants from wastewater - Long term pilot trials at Kungsängsverket WWTP, Uppsala, Sweden.

Pharmaceuticals and per- and polyfluoroalkyl substances (PFAS) are persistent organic micropollutants (OMPs) posing environmental and health risks due to their bioaccumulative nature and potential toxicity. These OMPs spread to the environment due to the extensive use in today's society. Conventional wastewater treatment plants (WWTPs) are not designed to effectively remove these contaminants, making WWTPs an important pathway, especially for pharmaceuticals, to the aquatic environment. This study investigates the efficiency of combining granular activated carbon (GAC) and anion exchange (AIX) for the removal of OMPs from wastewater. While GAC is a well-established method for removal of pharmaceuticals and AIX for PFAS removal, the combination of GAC and AIX for treating municipal wastewater has not been evaluated before. This research therefore focuses on long-term trials assessing the removal efficiencies of GAC and AIX filters in both bench-scale and pilot-scale setups at Kungsängsverket WWTP in Uppsala, Sweden. The combination of GAC and AIX filters showed over 90% removal efficiency for pharmaceuticals such as diclofenac up to 20,000 treated empty bed volumes (EBV). PFAS removal was primarily achieved by AIX after the initial 5000 EBV by GAC, highlighting the complementary roles of the two technologies. The findings contribute with new insights utilizing GAC and AIX as a combined treatment approach for reducing OMPs in municipal wastewater, contributing to improved environmental and public health outcomes.

Combining steric exclusion with anion exchange - development of a universal and scalable adeno-associated virus downstream process.

Adeno-associated viruses (AAV) are among the leading vectors for in vivo gene therapy. The purification of AAV remains a bottleneck as it typically requires multiple individual process steps, often resulting in product loss and high costs. Current downstream processes are usually serotype-specific and rely primarily on expensive affinity resins. To address these limitations, we developed a serotype-independent purification method using steric exclusion chromatography (SXC) that can be combined with a subsequent anion exchange full/empty separation step. This alternative approach eliminates the need for intermediate concentration and buffer exchange, thereby reducing the number of process steps required while achieving high-purity full AAV particles. SXC conditions were optimized using a design of experiments approach. Isocratic separation of full and empty AAV resulted in further purification of the sample. The overall process achieved a viral genome recovery of 51.7 %, along with impurity depletions of 99.9 % for DNA and 99.8 % for protein. The process was successfully adapted to different AAV serotypes and genes of interest, demonstrating its robustness and versatility. In addition, the scalability of SXC was demonstrated, highlighting its potential for large-scale manufacturing. This streamlined, universal, and scalable process provides a robust and efficient alternative to traditional AAV purification processes, addressing critical challenges in gene therapy production and paving the way for broader implementation in research and manufacturing.

A pyridinium-functionalized chitosan derivative as ecofriendly carrier for efficient adsorption and controlled release of 2,4-dichlorophenoxyacetic acid sodium.

Herbicides with wide use and low efficiency in agriculture severely threaten the environment. However, employing adsorbents and controlled-release formulations (CRFs) can alleviate these environmental risks. Herein, a pyridinium-functionalized chitosan derivative (PFCS) was prepared successfully and characterized by various techniques. The abundant cationic pyridinium groups enable PFCS to strongly adsorb a typical anionic herbicide, 2,4-dichlorophenoxyacetic acid sodium (2,4-D Na), across a broad pH range of 4 to 10. The adsorption kinetics follow the pseudo-second-order model, and the adsorption isotherms align with the Langmuir equation. The adsorption capacity can exceed 618.03 mg·g-1. Batch assays and further characterization reveal the mechanism of PFCS adsorbing 2,4-D Na anions mainly involves electrostatic attraction, anion exchange and other forces (e.g., π-π stacking and H bonding). Notably, PFCS loaded with 2,4-D Na (2,4-D@PFCS) demonstrates a significant sustained-release behavior, responding to changes in environmental pH and ion strength. The release rate was more influenced by ion strength than pH, and the release process adhered to a first-order kinetic model, primarily driven by ion exchange. Additionally, the 2,4-D@PFCS CRF has shown high biological efficacy on rapeseed. This work demonstrates the PFCS can effectively adsorb and control the release of anionic herbicides, minimizing their adverse impact on aquatic ecosystems.

Ligand-Engineered Hydrophilic Perovskite Enabling Surface Potential-Driven Anions Exchange for Multicolor Biosensing.

The difficulty in designing zwitterionic ligands impedes the water-dispersed CsPbX3 perovskite nanocrystals (NCs) and their application as fast anion exchange (FAE) probes in biosensing. This study proposes a design paradigm for zwitterionic ligands predicated upon revealing the mechanism of the SN2 reaction between unsaturated alkylamines (Cn') and haloalkanoic acids (HAAs). Among them, the C=C bond can enhance the nucleophilicity of Cn' and promote the electrostatic adsorption of HAAs onto Cn', i.e., the geometric preorganization process, thereby initiating the SN2 reaction. Moreover, an appropriate "bridge" length enables HAAs to balance the geometric preorganization process and the Sigma hole intensity of the C-Br bond. Zwitterionic ligands derived from oleylamine (C18') and 5-bromovaleric acid (5-BVA) endow CsPbBr3 NCs with water dispersibility, an almost 100% photoluminescence quantum yield, and enhanced surface potential, facilitating the capture of halide ions and driving the FAE reaction. Using AgI nanoparticles (NPs) as latent anion exchangers, a third FAE strategy is presented for multicolor biosensing. Such a robust biosensing strategy can generate wavelength shift and chromatic difference for biological target molecules, exemplified by H2S, and is ultimately applicable to multicolor assay in biological, environmental and food samples, demonstrating the immense potential of perovskite-based FAE probes in biosensing.

Ligand‐Engineered Hydrophilic Perovskite Enabling Surface Potential‐Driven Anions Exchange for Multicolor Biosensing

The difficulty in designing zwitterionic ligands impedes the water‐dispersed CsPbX3 perovskite nanocrystals (NCs) and their application as fast anion exchange (FAE) probes in biosensing. This study proposes a design paradigm for zwitterionic ligands predicated upon revealing the mechanism of the SN2 reaction between unsaturated alkylamines (Cn') and haloalkanoic acids (HAAs). Among them, the C=C bond can enhance the nucleophilicity of Cn' and promote the electrostatic adsorption of HAAs onto Cn', i.e., the geometric preorganization process, thereby initiating the SN2 reaction. Moreover, an appropriate “bridge” length enables HAAs to balance the geometric preorganization process and the Sigma hole intensity of the C‐Br bond. Zwitterionic ligands derived from oleylamine (C18') and 5‐bromovaleric acid (5‐BVA) endow CsPbBr3 NCs with water dispersibility, an almost 100% photoluminescence quantum yield, and enhanced surface potential, facilitating the capture of halide ions and driving the FAE reaction. Using AgI nanoparticles (NPs) as latent anion exchangers, a third FAE strategy is presented for multicolor biosensing. Such a robust biosensing strategy can generate wavelength shift and chromatic difference for biological target molecules, exemplified by H2S, and is ultimately applicable to multicolor assay in biological, environmental and food samples, demonstrating the immense potential of perovskite‐based FAE probes in biosensing.

Adsorptive removal of phosphate and nitrate by layered double hydroxides through the memory effect and in situ synthesis

This research examines the efficacy of layered double hydroxides (LDHs) in removing phosphate and nitrate from wastewater, enhanced by the memory effect and in situsynthesis techniques. LDHs were synthesized hydrothermally, initially creating carbonate-based CO₃–LDHs, which were then converted to chloride-based Cl–LDHs through anion exchange. These LDHs underwent calcination at 300 °C, 400 °C, and 500 °C to optimize their structure for enhanced adsorption capabilities. The synthesized LDHs were thoroughly characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and X-ray diffraction (XRD). Adsorption experiments in solutions with pH values between 5, 7, and 9 revealed the adsorption capacities of phosphate and nitrate on the CO₃–LDHs and Cl–LDH, respectively. The results indicated that LDHs calcined at 500 °C showed the highest adsorption performance, achieving maximum capacities of 184 mg/g for phosphate and 70.1 mg/g for nitrate. Kinetic studies confirmed that the adsorption process followed a pseudo-second-order model, demonstrating the effectiveness of the memory effect in enhancing ion exchange. The in situ synthesis of LDHs under controlled conditions significantly improved the removal rates of these anionic contaminants from wastewater, proving the potential of this method for the realistic wastewater treatment.