Ammonium Research Articles

Preparation of V2O3 by a short process of ammonium salt reduction and its electrocatalytic properties investigation

Ammonium salt vanadium precipitation is the main method of vanadium metallurgy at home and abroad, but the traditional ammonium precipitation of vanadium can only obtain high valence of V2O5, and the NH3 produced in the calcination process cannot be fully utilized. And the preparation of low-valence vanadium oxide V2O3 is long and costly. Self-reduction of thermal decomposition of nitrogen-containing precipitation products to produce V2O3 is a novel and short process method that can achieve full utilization of ammonia. NaVO3 was used as the vanadium source, choline chloride (C5H14ClNO (ChCl)) was used as the vanadium precipitation reagent, and the vanadium concentration was 30 g/L, n(ChCl)/n(V) = 1.5, the initial pH was 1.5, the temperature was 85°C, the time was 2 h, and the vanadium precipitation efficiency could reach 97.05%. V2O3 with purity of 97.98% can be obtained by calcination at 550°C for 3 h in an argon atmosphere. XRD, FTIR, XPS, SEM-EDS were used to characterize the product, which further proved that the final product was V2O3. The electrocatalytic hydrogen evolution reaction (HER) of V2O3 in acidic media showed high stability after 1000 cyclic voltammetry (CV) cycles, with a low Tafel slope of 88.5 mVdec−1. The electrochemical double layer capacitance (EDLC) was measured by CV at different scan rates, and the EDLC of V2O3 was 1.104 mFcm−2. This study provides a short-flow preparation method for V2O3 and can provide predictions for the application of V2O3 in HER and supercapacitors.

Fabrication of bare and cobalt-doped ZnFe2O4 thin film as NH3 gas sensor with enhanced response through UV-light illumination

This work reports on the deposition of bare and cobalt-doped ZnFe2O4 thin films by chemical spray pyrolysis technique to study ammonia (NH3) gas sensing properties. Colorless and strongly smelling, ammonia (NH3) is readily soluble in water and yields ammonium (NH) ions. These gases mix in the air atmosphere cause climate change, and severely affect human health. Therefore, the detection of NH3 below the exposure limit can avoid the deterioration of human health and environment. Co-doping had a significant effect on surface roughness, surface morphology, crystallite size, and sensitivity at room temperature. Co0.5Zn0.5Fe2O4 film (ZFCO5) exhibited an outstanding response (S = 19) towards 10 ppm NH3 gas at room temperature. Compared to the bare film, the ZFCO5 sensor has an eleven-fold higher gas-detection response value for 10 ppm NH3. This is ascribed to the blended effects of small crystallite size, high surface roughness, oxygen vacancies, and angular shape morphology linked into tiny rods in the ZFCO5 film. The ZFCO5 sensor showed a significant speedup in response/recovery times (102 s/34 s) and good response (S = 25) to NH3 under the UV-light (365 nm) illumination at room temperature. The built-in ZFCO5 gas sensor shows promise for real-time NH3 below threshold level monitoring.

Strategic control of combustion-induced ammonia emissions: A key initiative for substantial PM2.5 reduction in Tianjin, North China Plain

Information on the temporal and spatial variations in the sources of ammonium salts (NH4+), a crucial alkaline component in PM2.5, is limited. Here, we simultaneously collected PM2.5 and gaseous ammonia (NH3) samples in both summer and winter from two sites in Tianjin: an urban site (Tianjin University, TJU) and a suburban site (Binhai New-region, BH). NH3 concentrations, the contents of major water-soluble inorganic ions in PM2.5, and the compositions of ammonium‑nitrogen isotopes (δ15N-NH4+) were measured. As a result, (NH4)2SO4 and NH4NO3 were the predominant forms of NH4+ in PM2.5 during summer and winter, respectively. However, the NH4NO3 concentrations were notably greater at TJU (6.2 ± 7.3 μg m−3) than at BH (3.8 ± 4.7 μg m−3) in summer, with no regional differences observed in winter. Both sites displayed almost half the contribution of c-NH3 (combustion-related NH3) to NH4+, differing from the finding of previous isotope-based studies. This discrepancy could be attributed to the combined effects of NHx isotope fractionation and seasonal δ15N value variations in NH3 sources. The contribution fractions of v-NH3 (volatile NH3) and c-NH3 exhibited similar patterns at both sites seasonally, probably caused by coal combustion for heating in winter and temperature fluctuations. However, the contribution fraction of c-NH3 was lower at BH than at TJU in summer but greater in winter than at TJU. In summer, NH4NO3 was unstable and limited its delivery to TJU from BH, and the high contribution of c-NH3 to NH4+ at TJU could be attributed to local vehicle emissions. In winter, the stable particulate NH4NO3 that formed from the c-NH3 in the upwind area could be transported to the downwind area, increasing the NH4+ concentration at BH. Our study provides valuable insights for devising emission mitigation strategies to alleviate the increasing burden of NH3 in the local atmosphere.

Carbon nanotube incorporated quaternized lignin-based loose nanofiltration membrane toward dye/salt separation

Lignin is a promising raw material for membrane fabrication due to its abundant oxygen-containing functional groups, branched molecular structure, and high abundance in the botanic field. In this report, polydopamine (PDA) coated carbon nanotubes (PCNTs) are synthesized. Then, a PCNT-incorporated lignin-based loose nanofiltration membrane is fabricated using quaternized lignin (QL) as a raw material, triphosgene (TP) as a crosslinker, and PCNTs as nanoadditive by interfacial polymerization. The results show that the PCNTs uniformly distribute in the QL-based separation layer providing quick diffusion paths for water molecules and salt ions. The coated PDA layer improves the chemical compatibility between the PCNTs and the separation layer. The incorporated PCNTs optimize the membrane microstructure and elevate the pure water permeance to 45.5 LMH bar-1. The membrane exhibits high rejections to various dyes (> 90%) and high salt permeation (> 90%), demonstrating an excellent dye/salt separation performance. Moreover, it has satisfactory capabilities for resisting dye adsorption and fouling, and its separation capability also has good tolerances to the acid, alkali, and active chlorine treatments. The quaternary ammonium ions and hydrophilic surface endow the membrane with favorable bactericidal property (99.3%) and bacteria-adhesion resistance. Besides, TP is a better crosslinker than trimesoyl chloride for optimizing the membrane microstructure and crosslinking degree in terms of dye/salt separation.

Synthesis, characterization and antimicrobial evaluation of quaternary ammonium compounds from natural oils

Quaternary ammonium salts refer to any class of salt derived from ammonium in which the nitrogen atom is attached to four organic groups covalently, as in benzalkonium chloride (R4N+). Quaternary ammonium compounds were synthesized from Canola oil (Brasssicanapus) and Coconut oil (Cocos nucifera) extracts by reacting the oils with N,N-diethylethylenediamine in the presence of potassium tertiary butoxide as catalyst. Fourier Transform Infrared (FTIR) Spectrometric analyses of the starting materials, the intermediates and the final products were conducted, the results showed a disappearance of the carbonyl (C=O) stretch of an ester (the oil) at 1744cm-1 and appearance of N-H band of an amide at 3433cm-1, which resulted from the quaternization of benzyl chloride with the intermediates for both oils. Other functional groups such as C=C and C-H stretch of aromatic compound, C=O stretch of an amide were also observed.Mass spectrometric analysis of the final products were conducted and results showed the Molecular Ion peak (M+) which is the molecular weights of the products. Vital fragments such as base peaks were observed for both quats, other fragmented radical cations were observed.Antimicrobial activity of the synthesized Quaternary ammonium compounds (QACs) exhibited excellent anti-bacterial activity covering a diameter of 22 mm and 28 mm of E. coli for QACs from Cocos nucifera and Brassic anapus oils respectively as compared to the standard antibiotic (Ampillicin).

Electron Structure of α‐, β‐Te2MoO7 and Photocatalytic Decomposition of Antibiotics

AbstractTwo modifications of Te2MoO7 oxide have been prepared by different synthetic methods. The crystal structure and composition have been studied by X‐ray diffraction analysis and X‐ray microanalysis. The phase of α‐Te2MoO7 has been synthesized by solid‐state reaction from ammonium salts and characterized by monoclinic structure with P21/c. The β‐Te2MoO7 compound has been formed in hydrothermal conditions and has amorphous nature. The thermal behavior of β‐Te2MoO7 modification is characterized by the phase transition into α‐form, however after melting the amorphous state has restored. The electron structure has been investigated experimentally by X‐ray photoelectron spectroscopy and UV‐vis diffusion reflectance spectra and theoretically by approximation using atomic electronegativity. Despite the same composition, the band gap of β‐Te2MoO7 corresponds to visible light, whereas α‐Te2MoO7 adsorbs light in UV region. The both modifications are able to generate superoxide radicals in vacuum or air and hydroxyl radicals in water under irradiation. The HPLC‐MS analysis has shown the quite deep decomposition of dye and antibiotics by α‐Te2MoO7, whereas amorphous phase almost does not lead to any oxidation.

Different Fracture Liquids under the Action of Enclosure of Dense Sandstone Reservoir Micro-Damage Characteristics Study

The sandstone reservoir in the Lule River group of Mahai East District is strong, densely dense, and the expansion of clay material is very easy to block the pores. Therefore, the new pressure cracks and cationic cluster stabilizers with double-season ammonium salt clay stabilizers are used. Experimental analysis is performed under the circumstances of the perimeter. Use nuclear magnetic real-time testing different fracture liquids to drive the pore structure structure changes before and after the sandstone, combined with differential theory to calculate the fractal dimensions of sandstone. As a result, under the condition of water full, as the perimeter pressure increases, the rocks are increased, and the rocks are increased, and the rocks are increased. The matrix occurs under the common action of the fence and the fracture fluid to prevent the inflation of clay minerals under the combined action of the fence and the fracture fluid, which causes a significant reduction in large holes and increased micropores and medium holes. Exploring different fracture liquids to reservoirs is of great significance to the development of dense sandstone reservoirs.

Zero-field J-spectroscopy of quadrupolar nuclei

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) allows molecular structure elucidation via measurement of electron-mediated spin-spin J-couplings. This study examines zero-field J-spectra from molecules with quadrupolar nuclei, exemplified by solutions of various isotopologues of ammonium cations. The spectra reveal differences between various isotopologues upon extracting precise J-coupling values from pulse-acquire measurements. A primary isotope effect, △J=γ14N/γ15NJ15NH−J14NH≈−58\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ riangle J=\\left({\\gamma }_{{}^{14}{{{{{\\rm{N}}}}}}}/{\\gamma }_{{}^{15}{{{{{\\rm{N}}}}}}}\\right){J}_{{}^{15}{{{{{\\rm{N}}}}}}{{{{{\\rm{H}}}}}}}-{J}_{{}^{14}{{{{{\\rm{N}}}}}}{{{{{\\rm{H}}}}}}}\\approx -58$$\\end{document} mHz, is deduced by analysis of the proton-nitrogen J-coupling ratios. This study points toward further experiments with symmetric cations containing quadrupolar nuclei, promising applications in biomedicine, energy storage, and benchmarking quantum chemistry calculations.

Chiral Tetrakis Eu(III) Complexes with Ammonium Cations for Improved Circularly Polarized Luminescence

Large dissymmetry factor of the circularly polarized luminescence (gCPL) was observed in ligand and coordination tuned chiral tetrakis europium (Eu(III)) complexes with ammonium cations. The gCPL value was estimated to be −1.54, which is the largest among chiral luminescent molecules. Through photophysical measurements, single crystal X‐ray structural analyses and quantum chemical calculations, changes in the geometric and electronic structures were observed for a series of chiral tetrakis Eu(III) complexes which enhanced the gCPL value. The emission quantum yield and photosensitized energy transfer efficiencies of chiral Eu(III) complexes with ammonium cations were also larger than that with previous Cs+. Based on the systematic modifications and analyses for chiral tetrakis Eu(III) complex, effect of the ammonium cation on enhanced CPL brightness is reported.

Chiral Tetrakis Eu(III) Complexes with Ammonium Cations for Improved Circularly Polarized Luminescence.

Largedissymmetry factor of the circularly polarized luminescence (gCPL) was observed in ligand andcoordinationtuned chiral tetrakis europium (Eu(III)) complexes with ammonium cations. ThegCPLvalue was estimated to be -1.54,which is the largest among chiral luminescent molecules. Through photophysical measurements,single crystal X-ray structural analysesand quantum chemical calculations, changes in the geometric and electronic structures were observed for a series of chiral tetrakis Eu(III) complexes which enhanced thegCPLvalue.The emission quantum yield andphotosensitized energy transfer efficiencies of chiral Eu(III) complexes with ammonium cations were also larger than that with previous Cs+.Based on the systematicmodifications and analyses for chiraltetrakisEu(III) complex, effect of the ammonium cation on enhanced CPL brightness is reported.

The Integral Role of Conjugate Acids in Brønsted Base‐Catalyzed Regiodivergent Synthesis

Catalyst‐controlled diversity‐oriented synthesis (CatDOS) is an important research area for expanding molecular complexities and achieving high atomic economics. Plenty of regiodivergent syntheses have been achieved through metal catalysis, covalent and non‐covalent organocatalysis by controlling the molecular recognition function of the catalysts. However, the development of regiodivergent CatDOS through Brønsted base in organocatalysis was relatively less than others. Numerous studies about Brønsted base organocatalysis have demonstrated the powerful molecular recognition abilities of their cationic conjugate acids (CA) mainly in controlling the stereoselectivity instead of the regioselectivity. This concept review aims to conceptualize a new perspective to consider the potential role of the cationic CA of Brønsted bases for regiodivergent CatDOS. Recent representative examples are selected to demonstrate the potential of cationic CA on site‐selectivity control in single‐bond and multiple‐bond formation reactions. The summarized results show that even CA of common tertiary amines, protic ammonium ions, could affect the regioselectivity in the early‐ or late‐stage step during multiple‐bond formation after initial deprotonation. The results also hinted that the properties and ion‐pairing interactions of CA could be more important than the basicity of bases in controlling regioselectivity. Perspectives and hypotheses for explanation of the mechanism of regioselectivity are also included in this review.

Order-to-Disorder Transition and Hydrogen Bonding in the Jahn-Teller Active NH4CrF3 Fluoroperovskite.

Large quantities of high-purity NH4CrF3 have been synthesized using a wet-chemical method, and its structural chemistry and magnetic properties are investigated in detail for the first time. NH4CrF3 is a tetragonal fluoroperovskite that displays an ordering of the ammonium (NH4+) groups at room temperature and C-type orbital ordering. The ammonium groups order and display distinct signs of hydrogen bonds to nearby fluoride anions by buckling the Cr-F-Cr angle away from 180°. The ammonium ordering remains up to 405 K, much higher than in other ammonium fluoroperovskites, indicating a correlation between the flexibility of the Jahn-Teller ion, the hydrogen bond formation, and the ammonium ordering. At 405 K, an order-to-disorder transition occurs, where the ammonium groups disorder, corresponding to a transition to higher symmetry. This is accompanied by a contraction of the unit cell from breaking hydrogen bonds, similar to the phenomenon observed in water ice melting. The compound orders antiferromagnetically with a Neél temperature of 60 K, an effective paramagnetic moment of 4.3 μB, and a Weiss temperature of -33 K. An A-type antiferromagnetic structure is identified by neutron diffraction, with an ordered moment of 3.72(2) μB.

Choice of the Right Supporting Electrolyte in Electrochemical Reductions: A Principal Component Analysis.

We present an analysis of a set of molecular, electrical, and electronic properties for a large number of the cations of quaternary ammonium salts usually employed as supporting electrolytes in cathodic reduction reactions. The goal of the present study is to define a measure for the quality of a supporting electrolyte in terms of the yield of the reaction considered. We performed a principal component analysis using the normalized values of the properties in order to lower the number of relevant reaction coordinates and find that the integral variance of 13 properties can well be represented by three principal components. The yield of the electrochemical hydrodimerization of acrylonitrile employing different quaternary ammonium salts as supporting electrolytes was determined in a series of experiments. We found only a very weak correlation between the yield and the values of the properties but a strong correlation between the yield and the values of the most important principal component. Very similar results are obtained for two further existing systematic experimental studies of the impact of the supporting electrolyte on the yield of cathodic reductions. For all three example reactions, a supervised regression using the two most important principal components as variables yields excellent values for the coefficients of determination. For comparison, we also applied our methodology to sets of purely structure-based features that are usually employed in cheminformatics and obtained results of almost similar quality. We therefore conjecture that our methodology in combination with a small number of experiments can be used to predict the yield of a given cathodic reduction on the basis of the properties of the supporting electrolyte.

Two approaches to prepare cationic lignin‐based adsorbents for efficient removal of phosphate ion from wastewater

AbstractIn this work, two types of cationic lignin‐based adsorbents (AL‐METAC and AL‐GTA) were prepared through free radical polymerization or etherification reaction of alkali lignin with 2,3‐epoxypropyl‐3‐trimethylammonium chloride or methylacrylloxyethyl trimethyl ammonium chloride (METAC). The contents of quaternary ammonium groups in the adsorbents were adjusted by changing the dosages of 2,3‐epoxypropyl‐3‐trimethylammonium chloride and METAC to fabricate the adsorbents with excellent adsorption capacity. The structures, aqueous solubility, and physical properties of adsorbents were analyzed. Meanwhile, the effects of adsorbents dosage, pH value of solution, temperature, and ionic strength on the adsorption capacity of adsorbents were also analyzed. These two types of adsorbents exhibited outstanding affinity for phosphate, with a maximum removal efficiency of 51.8 and 73.2 mg/g, respectively. The adsorption processes followed pseudo‐second‐order and Langmuir models well. In addition, the AL‐GTA exhibited higher removal efficiency than AL‐METAC. Moreover, the AL‐METAC and AL‐GTA still retained 69.7% and 69.0% adsorption capacity after four times regeneration. The fabricated lignin‐based adsorbents have potential applications in the removal of phosphate from wastewater, which would promote the high‐value application of lignin.

Associations between PM2.5 Components and Mortality of Ischemic Stroke, Chronic Obstructive Pulmonary Disease and Diabetes in Beijing, China

Ischemic stroke (IS), chronic obstructive pulmonary disease (COPD) and diabetes mellitus (DM) account for a large burden of premature deaths. However, few studies have investigated the associations between fine particular matter (PM2.5) components and mortality of IS, COPD and DM. We aimed to examine these associations in Beijing, China. Data on daily mortality, air pollutants and meteorological factors from 2008 to 2011 in Beijing were collected. Daily concentrations of five PM2.5 components, namely, sulfate ion (SO42−), ammonium ion (NH4+), nitrate ion (NO3−), organic matter (OM) and black carbon (BC), were obtained from the Tracking Air Pollution (TAP) database in China. The association between PM2.5 components and daily deaths was explored using a quasi-Poisson regression with the distributed lag nonlinear model (DLNM). The average daily concentrations of SO42−, NH4+, NO3−, OM and BC were 11.24, 8.37, 12.00, 17.34 and 3.32 μg/m3, respectively. After adjusting for temperature, relative humidity, pressure, particulate matter less than 10 μm in aerodynamic diameter (PM10), nitrogen dioxide (NO2) and sulfur dioxide (SO2), an IQR increase in OM at lag day 2 and lag day 6 was associated with an increased DM mortality risk (RR 1.038; 95% CI: 1.005–1.071) and COPD mortality risk (RR 1.013; 95% CI: 1.001–1.026). An IQR increase in BC at lag day 0 and lag day 6 was associated with increased COPD mortality risk (RR 1.228; 95% CI: 1.017–1.48, RR 1.059; 95% CI: 1.001–1.121). Cumulative exposure to SO42− and NH4+ was associated with an increased mortality risk for IS, with the highest effect found for lag of 0–7 days (RR 1.085; 95% CI: 1.010–1.167, RR 1.083; 95% CI: 1.003–1.169). These effects varied by sex and age group. This study demonstrated associations of short-term exposure to PM2.5 components with increased risk of IS, COPD and DM mortality in the general population. Our study also highlighted susceptible subgroups.

Enhanced Efficiency and Stability of Wide‐Bandgap Perovskites via Br‐Rich Bulk and Surface 2D Passivation for Indoor Photovoltaics

Indoor photovoltaics (IPV) is a promising technology to power the rapidly developing Internet of Things (IoT) devices, offering advantages of distributed power source and reduced maintenance cost. Wide‐bandgap perovskite solar cells (PSCs), with the features of easy bandgap tuning and low‐cost solution process, hold significant potential for powering indoor IoT devices. However, the efficiency and stability of wide‐bandgap PSCs suffers from severe phase segregation and surface defects. Here we introduce a novel bromide‐rich 2D passivation strategy targeting both bulk and surface passivation of wide‐bandgap PSCs for IPV application. Ammonium salts with optimized alkyl chain length is confirmed to suppress the phase segregation in the bulk. Bromide‐rich 2D perovskite exhibit superior performance compared to their iodide counterparts, effectively suppressing nonradiative recombination and forming favourable energy band alignment with the ETL. The wide‐bandgap PSCs achieved an impressive PCE up to 41.58% under 1000 lux LED illumination. Furthermore, the wide‐bandgap perovskite module efficiently powers a Bluetooth IoT sensor at 400 lux indoor illumination, which can sense and broadcast the environmental information. This work highlights the remarkable potential of wide‐bandgap PSCs for indoor IoT devices and provides valuable insights into enhancing the efficiency and stability of PSCs for future IoT applications.This article is protected by copyright. All rights reserved.

Assessment of dumpsites leachate, geotechnical properties of the soil, and their impacts on surface and groundwater quality of Sunyani, Ghana

Leachate from sanitary landfill and dumpsites have potential to cause soil and groundwater contamination, and disrupt ecosystems. However, there is little information about dumpsite leachates and geotechnical properties and their impacts on surface and groundwater in Bono region, Ghana. This study assessed dumpsites leachate, geotechnical properties of the soil, and their impacts on surface and groundwater quality in Sunyani. Six triplicate leachates, eleven triplicate groundwater and three triplicate surface water samples were taken at (up-stream, mid-stream and down-stream) urban dumpsite, and eight triplicate groundwater samples taken around peri-urban dumpsite. Water samples were stored (<4°C) in polyethylene bottle for laboratory analysis. Physicochemical properties of leachate and water samples were analyzed using standard methods. Heavy metals (Cd, Hg, Pb, Zn, Cr, Fe, Cu, and Ni) were determined using atomic absorption spectroscopy. Water quality index (WQI) and leachate pollution loads (LPL) were investigated, while plasticity index (Ip) and liquid index (Il) were determined using Atterberg limit test. The results showed that all leachate samples were heavily polluted with mean concentrations of chlorides ranged between (2830±220 and 63810±340), biochemical oxygen demand (358±36 to 820±80), ammonium ions (82.8±2.2 to 267.6±62), and cadmium (0.49±0.02 to 5.32±1.0); with their leachate pollution index (LPI) and LPL exceeding their leachate disposal standards (LDS>100). WQI ranged from 6.51 to 289, indicating excellent to heavily polluted groundwater sources. Surface water was heavily polluted with WQI between 0.84 and 776.75, with majority having WQI>100. The heavily polluted samples were located 75-155 m away from urban dumpsite. Moderate significant negative association was established between (WQI-P and WQI-H) and distance with multiple R2=0.4709, p=0.0191 and R2= 0.4482, p=0.02425 respectively. Statistically, strong significant negative association between (WQI-P & WQI-H) and Ip (p < 0.05). This implies that when plasticity index and distance from groundwater sources to dumpsite increased, WQI values decreased, and groundwater quality improved.

Characterization and Performance Evaluation of Digital Light Processing 3D Printed Functional Anion Exchange Membranes in Electrodialysis

With the rapid development of 3D printing technologies, more attention has been focused on using 3D printing for the fabrication of membranes. This study investigated the application of digital light processing (DLP) 3D printing combined with quaternization processes to develop dense anion exchange membranes (AEMs) for electrodialysis (ED) separation of Cl− and SO42− ions. It was discovered that at optimal curing times of 40 min, the membrane pore density was significantly enhanced and the surface roughness was reduced, and this resulted in an elevation of desalination rates (97.5–98.7%) and concentration rates (165.8–174.1%) of the ED process. Furthermore, increasing the number of printed layers improved the membranes’ overall polymerization and performance, with double-layer printing showing superior ion flux. This study also highlights the impact of the polyethylene glycol diacrylate (PEGDA) molecular weight on membrane efficacy, where PEGDA-700 outperformed PEGDA-400 in ion transport capabilities and desalination efficiency. Additionally, higher 4-vinylbenzyl chloride (VBC) content improved the quaternary ammonium group concentration and membrane conductivity, and hence elevated the ED performance. Under optimized conditions, DLP 3D printed membranes demonstrated exceptional selectivity of 24.0 for Cl−/SO42− and a selective purity of 81.4%. With a current density of 400 A/m2, the current efficiency and energy consumption were in the range of 82.4% to 99.7%, and 17.2 to 25.4 kW‧h‧kg−1, respectively, showcasing the potential of advanced manufacturing techniques in creating efficient and functional ion exchange membranes.

Structural Features of Styrene-Functionalized Cyclodextrin Polymers That Promote the Adsorption of Perfluoroalkyl Acids in Water.

Cross-linked β-cyclodextrin (β-CD) polymers are promising adsorbents for the removal of per- and polyfluoroalkyl substances (PFAS) from contaminated water sources, including contaminated groundwater, drinking water, and wastewater. We previously reported porous, styrene-functionalized β-cyclodextrin (StyDex) polymers derived from radical polymerization with vinyl comonomers. Because of the versatility of these polymerizations, StyDex polymer compositions are tunable, which facilitates efforts to establish structure-adsorption relationships and to discover improved materials. Here, we evaluate the material properties and PFAS adsorption of 20 StyDex derivatives with varied comonomer structure and loading, regiochemistry of styrene placement on the CD monomer, and CD size. A StyDex polymer containing N,N'-dimethylbutyl ammonium ions exhibited the most effective PFAS adsorption in batch experiments. Furthermore, a StyDex polymer containing β-CD exhibited size-selective host-guest interactions with perfluoroalkyl acids (PFAAs) and neutral contaminants in aqueous electrolyte when compared to similar polymers containing either α-CD or γ-CD. Polymers based on β-CD monomers with an average of seven styrene groups randomly positioned over the 21 available hydroxyl groups performed similarly to those based on a β-CD monomer functionalized regiospecifically at each of the seven 6' positions. The former β-CD monomer is prepared in a single step from unmodified β-CD, so the ability to use it without compromising performance demonstrates promise for developing economically competitive adsorbents. These results offered important insights into structure-adsorption properties of StyDex polymers and will inform the design of improved StyDex formulations.

Green and sustainable hydrogels based on quaternized chitosan to enhance wound healing

Hydrogel-based biomaterials applied as wound dressings provide the wound with a moist environment, which facilitates tissue regeneration through granulation and re-epithelialization. The inherent flexibility and adjustable architecture of hydrogels enables incorporation of cells, antimicrobial drugs, growth factors, and bioactive compounds, which leads to expediting wound contraction and enhancing the regeneration process. The utilization of natural polysaccharides, particularly chitosan, as a green and one of the most sustainable biomaterials among renewable resources, has been widely practised in wound healing because of its promising cost-effectiveness, biocompatibility, and biodegradability. However, the challenge of limited solubility of chitosan at neutral or basic media (pH ≥ 6.5) has been pinpointed. The exploration of quaternary chitosan hydrogels was a big step to combat its low solubility through the contribution of a quaternary ammonium group that improves the hydrophilicity and additionally brings about antibacterial activity over a wide range of pH. This review summarizes the latest progress in using hydrogel dressings based on quaternized chitosan for wound regeneration, encompassing various aspects such as hemostasis, antibacterial activity, antioxidant properties, and overall wound healing efficacy. Furthermore, the present review addresses the existing challenges and proposes possible solutions to enlarge development avenues in pursue of optimizing wound regeneration performance of quaternized chitosan-based hydrogels in prospect.