Search Results (137)

The enzymatic production of prebiotic galactooligosaccharides (GOS), functional food ingredients with established health benefits, remains an active research area driven by a rising global demand for GOS. These oligosaccharides are synthesized from lactose via transgalactosylation catalyzed by β-galactosidase, accompanied by hydrolysis of both substrate and products, and the competition between these reactions critically determines the maximum achievable GOS yield. In this study, β-galactosidase from Aspergillus oryzae was immobilized on an anion-exchange resin (Dowex Marathon MSA) using three glutaraldehyde-based crosslinking strategies. The resulting immobilized biocatalysts were characterized and evaluated for GOS synthesis, with product yield as the principal performance indicator. The results demonstrated that the immobilized biocatalysts markedly modulated the balance between transgalactosylation and hydrolytic activities. The biocatalyst prepared by simultaneous resin activation and enzyme crosslinking provided the highest GOS yield and operational stability. This biocatalyst was subsequently used to study the effects of lactose concentration, pH, enzyme loading, and temperature. Among these, lactose concentration most strongly influenced GOS yield, whereas the other factors primarily affected the reaction rate. These findings offer practical insights into enzyme immobilization strategies for optimizing GOS production. Full article

Radioactive organic anion exchange resins present a significant challenge in nuclear power plant waste disposal due to their volatility, instability, and biotoxicity. Based on experimental degradation data from the supercritical water oxidation (SCWO) of organic anion exchange resin waste liquids from the nuclear industry, this study conducted correlation analysis, cluster analysis, and Sobol sensitivity analysis of key process parameters. The results indicate that temperature is the primary factor influencing chemical oxygen demand (COD) and total nitrogen (TN) removal, while oxidant dosage exhibits a notable synergistic effect on nitrogen transformation. A Gaussian Process Regression–Non-Dominated Sorting Genetic Algorithm II (GPR–NSGA-II) multi-objective optimization model was developed to balance COD/TN removal rate and treatment cost. The optimal operating conditions were identified as a temperature of 472.2 °C, an oxidant stoichiometric ratio (OR) of 136%, an initial COD concentration of 73,124 mg·L⁻¹, and a residence time of 3.8 min. Under these conditions, COD and TN removal efficiencies reached 99.63% and 32.92%, respectively, with a treatment cost of 128.16 USD·t⁻¹. The proposed GPR–NSGA-II optimization strategy provides a methodological foundation for process design and economic assessment of SCWO in treating radioactive organic resin waste liquids and can be extended to other studies involving high-concentration, refractory organic wastewater treatment. Full article

Dendrobium moschatum neutral polysaccharide (DMP-NP) was isolated using a water extraction–ethanol precipitation method, followed by purification with DEAE-cellulose anion-exchange resin and a dextran gel column. The resulting DMP-NP1 exhibited a weight-average molecular weight of 16.23 kDa. The molar ratio of monosaccharides was as follows: glucose–mannose–galactose–fucose–rhamnose = 78.54:19.11:1.59:0.53:0.23, with a glucose-to-mannose ratio of 4.1:1. Infrared spectroscopic analysis revealed characteristic carbohydrate absorption peaks and confirmed the presence of pyranosidic linkages. NMR analysis revealed that DMP-NP1 possesses a backbone mainly formed by 1→4 glycosidic linkages, a small number of 1→6 branches, and O-acetyl substitutions at the C2 and C3 positions of mannose residues. In vitro experiments demonstrated that treatment with 0–20 μg/mL (0–1.23 μM) DMP-NP significantly enhanced the activities of catalase (CAT) and superoxide dismutase (SOD) in IPEC-J2 cells, along with upregulation of the corresponding antioxidant genes. Concurrently, DMP-NP reduced the secretion of key pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, and downregulated the expression of genes associated with both antioxidant and inflammatory signaling pathways. Collectively, these findings indicate that DMP-NP not only prevents but also ameliorates LPS-induced inflammatory injury in intestinal epithelial cells, thereby providing a basis for the application of DMP-NP in intestinal inflammation mitigation. Full article

Inspired by the mechanism of ion exchange resins, this study is a first-report in constructing a dual-layer photocathodic protective coating with ionic selectivity to enhance corrosion resistance property. The microstructure, composition, and ion selectivity of the coating are characterized by scanning electron microscopy, Raman spectroscopy, infrared spectroscopy, and membrane potential. It shows that the outer g-C₃N₄/TiO₂ cation-selective layer plays a role in preventing corrosive Cl⁻ ions passing through the coating; the inner g-C₃N₄-TiO₂-CTAB anion-selective layer could prevent Fe²⁺ ions from diffusing through the coating. Furthermore, the coated carbon steel sample demonstrates a minimum OCP (open circuit potential) value of −770 mV (vs. SCE) under illumination in 3.5% NaCl media. Interestingly, the OCP remains around −720 mV (vs. SCE) even after light deprivation. The synergistic effect between ion selectivity and photocathodic protection is described, in detail, in the following. Full article

The provision of potable water for armed forces at their operational sites necessitates a robust treatment chain to ensure the production of safe drinking water from potentially contaminated local water sources. Relying on single-use water bottles is not considered an eco-friendly option and on-site production may exhibit limited efficiency depending on the water contamination. This study therefore aimed to define a mobile processing chain that could efficiently produce drinking water on-site while offering a multi-barrier level of protection. To evaluate the system, contaminated water was prepared from different water sources and then spiked with various inorganic contaminants (metals, anions: Cl⁻, F⁻, I⁻, NO₂⁻, NO₃⁻, SO₄²⁻, CN⁻), organic contaminants (e.g., pesticides, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, chlorinated solvents), and energetic compound (perchlorate) at levels ranging from 5 to 50 times the standard water quality criteria. A specific treatment process was defined optimized and evaluated at flow rates reaching 500 L/h. This treatment chain includes the following: a sediment filter, a greensand filter, a cation exchange resin, an anion exchange resin, an activated carbon adsorption filter, ultrafiltration, a UV lamp, and a reverse osmosis (RO) unit. This treatment system successfully met all water quality criteria, providing a reliable and effective alternative to an RO-only treatment regime. Full article

Chromium (Cr), a toxic heavy metal, poses significant environmental and health risks when industrial effluents containing Cr are discharged untreated. Addressing this challenge, this study developed a selective chromium removal strategy using IRA-900 resin in a sulfuric acid system with sodium phosphite (NaH₂PO₃) as a complexing agent. In the NaH₂PO₃-H₂SO₄ system, IRA-900 resin exhibited exceptional selectivity for Cr³⁺ with minimal co-adsorption of competing ions. The adsorption process followed the Langmuir isotherm model (R² > 0.99), indicating monolayer chemisorption dominated by homogeneous active sites, and achieved a maximum capacity of 103.56 mg·g⁻¹. Characterization via XPS, FT-IR, and SEM-EDS revealed a two-step mechanism: Cr³⁺ reacts with H₂PO₃⁻ to form an anionic complex, and then the complex undergoes electrostatic interaction and ion exchange with chloride ions (Cl⁻) on the quaternary ammonium groups of the resin. The chromium-loaded resin demonstrated remarkable structural stability, resisting Cr³⁺ desorption under conventional elution conditions. This property provides a novel pathway for chromium solidification in industrial wastewater, effectively minimizing secondary pollution risks. This work advances the design of ligand-assisted ion-exchange systems for targeted heavy metal removal, offering both high selectivity and environmental compatibility in wastewater treatment. Full article

In the production of recombinant antibody/Fc-fusion proteins using mammalian cells, many aggregates often form alongside the target proteins, particularly with bispecific antibodies. To ensure the safety of biological products, it is essential to control the amount of aggregates within a specific range. A traditional downstream process typically involves using Protein A (ProA) resin to capture the target antibody, followed by two polishing steps to ensure purity; for instance, using an anion exchange chromatography (AEX) in flow-through mode and a cation exchange chromatography (CEX) in binding–elution mode. In this study, we choose a Dual Action Fab (DAF), which can bind two antigens and is prone to aggregation when expression in CHO (Chinese Hamster Ovary) cells. We introduce hydrophobic interaction membrane chromatography (HIMC) operating in flow-through mode, which enhances production efficiency while reducing costs and the risks associated with column packing. We evaluated the impact of the operating buffer system, as well as the pH and conductivity of the loading samples, on aggregate removal using HIMC. Additionally, we investigated the mechanism of aggregate binding and found that loading conditions had a limited impact on this process. Overall, our findings indicate that employing HIMC can achieve a 20% reduction in aggregate levels. These results demonstrate that HIMC in flow-through mode is an effective and robust approach for reducing aggregates during antibody purification. Full article

In this study, a commercial anion-exchange resin (D301), known for high regenerability but limited selectivity, was chemically modified to enhance its sorption performance. The modification included graft polymerization of glycidyl methacrylate followed by thiourea functionalization, yielding a new sorbent, TD301, with chelating functional groups. Characterization using SEM/EDS, IR spectroscopy, XPS, and zeta potential measurements confirmed the successful introduction of sulfur- and nitrogen-containing groups, increased surface roughness, and decreased surface charge in the pH range 2–6. These changes shifted the sorption mechanism from nonspecific ion exchange to selective coordination. Sorption properties of TD301 were evaluated in mono- and bimetallic Mo–W systems, as well as in solutions obtained from real ore decomposition. The modified sorbent showed fast sorption kinetics and high selectivity for Mo(VI) at pH 1.5, while retaining high W(VI) uptake at pH 0.5. In binary systems, separation factors (α) reached 128.4, greatly exceeding those of unmodified D301. In real leachates (Mo ≈ W ≈ 0.04 g/L), TD301 selectively extracted W at pH 0.66 and Mo at pH 1.5. These findings demonstrate that TD301 is an effective sorbent for pH-dependent Mo/W separation in complex matrices, with potential for resource recovery, wastewater treatment, monitoring, and suitability for repeated use. Full article

Structural analysis of glycosphingolipids provides novel insights into organismal classification and reveals conserved functional roles that transcend taxonomic boundaries. To elucidate the structural characteristics of acidic glycosphingolipids (AGLs) in the adductor muscle of the Japanese giant scallop (Patinopecten yessoensis), AGLs were isolated and purified by column chromatography using anion exchange resin and silica gel. Structural characterization was performed using mass spectrometry, proton nuclear magnetic resonance spectroscopy, and immunological techniques. The sugar chain structure was identified as GlcA4Meβ1-4(GalNAc3Meα1-3)Fucα1-4GlcNAcβ1-2Manα1-3Manβ1-4Glcβ1-Cer, consistent with the mollu-series core reported for mollusks. In addition to uronic acid, the structure was distinguished by internal fucose and methylated sugars, features commonly found in bivalves. The presence of xylose in the sugar chains of AGLs was also suggested. In contrast, the ceramide moiety was composed primarily of fatty acids C16:0 and C18:0 and the long-chain base d16:1. This chemical structure provides valuable insights into the biological classification of P. yessoensis and the mollu-series glycolipids containing fucose and methylated sugars, which may serve as bioactive components shared across species in the phylum Mollusca and class Bivalvia. Full article

The efficient recovery of rhenium (Re), a critical metal in high-tech industries, is essential to address its growing demand and reduce reliance on primary mining. In this study, we developed novel anion-exchange resins for the selective adsorption and recovery of Re(VII) ions from acidic solutions, simulating industrial by-products. The resins were synthesized from a vinylbenzyl chloride-co-divinylbenzene copolymer modified with aliphatic, heterocyclic, and aromatic weakly basic amines, selected from among bis(3-aminopropyl)amine (BAPA), 1-(2-pyrimidinyl)piperazine (PIP), thiosemicarbazide (TSC), 2-amino-3-hydroxypyridine (AHP), 1-(2-hydroxyethyl)piperazine (HEP), 4-amino-2,6-dihydroxypyrimidine (AHPI), and 2-thiazolamine (TA). The adsorption of Re on BAPA, PIP, and HEP resins obeyed the Langmuir model, and the resins exhibited high adsorption capacities, with maximum values reaching 435.4 mg Re g⁻¹ at pH 6. Furthermore, strong selectivity for ReO₄⁻ ions over competing species, including Mo, Cu, and V, was noted in solutions simulating the leachates of the by-products of Cu-Mo ores. Additionally, complete elution of Re was possible. The developed resins turned out to be highly suitable for the continuous-flow-mode adsorption of ReO₄⁻, revealing outstanding adsorption capacities before reaching column breakthrough. In this context, the novel anion-exchange resins developed offer a reference for further Re recovery strategies. Full article

The deep defluorination of water remains a significant environmental challenge. In this work, aluminum was loaded onto the bifunctional resin S957 containing a phosphoric-sulfonic acid difunctional group for efficient fluoride removal. Al-S957 demonstrated excellent fluoride removal performance across a broad pH range. When anions and organics coexisted, Al-S957 exhibited significantly better fluoride adsorption performance compared to aluminum-loaded monofunctional resins. The adsorption followed an endothermic chemisorption process on a monolayer surface. FTIR and XPS analyses further revealed that fluoride removal relied on a ligand exchange mechanism. Column adsorption conducted over five cycles highlighted the strong practical potential of Al-S957. The results suggested that Al-S957 exhibits significant potential for practical applications. Full article

Rare earth metals (REMs) are vital for high-tech industries, but their extraction from secondary sources is challenging due to environmental and technical constraints. This study investigates the ion-exchange extraction of light REMs (neodymium, praseodymium, and samarium) from sulfuric and phosphoric acid solutions, modeling industrial leachates from apatite concentrates and phosphogypsum. The study considers the use of anion- and cation-exchange resins with different functional groups for efficient and environmentally safe REM separation. Experimental sorption isotherms were obtained under static conditions at 298 K and analyzed using a thermodynamic model based on the linearization of the mass action equation. Equilibrium constants and Gibbs energy were calculated, which reveals the spontaneity of the processes. Cation-exchange resins demonstrated high selectivity towards individual REMs, while anion-exchange resins were suitable for group extraction. Infrared spectral analysis confirmed the presence of sulfate and phosphate complexes in the resin matrix, clarifying the ion-exchange mechanisms. Thermal effect measurements indicated exothermic sorption on anion-exchange resins with negative entropy and endothermic sorption on cation-exchange resins with positive entropy. The findings highlight the potential of ion-exchange resins for selective and sustainable REM recovery, offering a safer alternative to liquid extraction and enabling the valorization of industrial wastes like phosphogypsum for resource recovery. Full article

Industrial technologies for processing tungsten concentrates using soda roasting or autoclave leaching are based on the production of alkaline sodium tungstate solutions that contain impurities such as silicon, phosphorus, arsenic, and others. The purification of these solutions from impurities requires the neutralization of excess soda or alkali with inorganic acids, which leads to the formation of chloride and sulfate effluents that are subsequently discharged into waste repositories. An analysis was carried out on existing methods for the production and processing of sodium tungstate solutions using HNO₃ and NH₃, as well as extraction and sorption techniques involving anion exchange resins. Currently, processes such as nanofiltration, reverse osmosis, and electrodialysis are being applied for water purification and the treatment of sulfate and chloride effluents. These processes employ various types of industrially manufactured membranes. For the purpose of electrodialysis, a two-compartment electrodialyzer setup was employed using cation-exchange membranes of the MK-40 (Russia) and EDC1R (China) types. The composition and structure of sodium tungstate, used as the starting reagents, were analyzed. Based on experiments conducted on a laboratory-scale unit with continuous circulation of the catholyte and anolyte, dependencies of various parameters on current density and process duration were established. Stepwise changes in the anolyte pH were recorded, indirectly confirming changes in the composition of the Na₂WO₄ solution, including the formation of polytungstates of variable composition and the production of H₂WO₄ via electrodialysis at pH < 2. The resulting tungstic acid solutions were also analyzed. The conducted studies on the processing of sodium tungstate solutions using electrodialysis made it possible to obtain alkaline solutions and tungstic acid at a current density of 500–1500 A/m², without the use of acid for neutralization. Yellow tungstic acid was obtained from the tungstic acid solution by evaporation. Full article

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are emerging contaminants of concern as they persist in natural environments due to their unique chemical structures. This paper critically reviewed the adsorption of PFOA and PFOS, depending on their chemical structure, by different adsorbents as well as soil. Adsorption of PFOS generally surpasses that of PFOA across various adsorbents. Despite having the same number of carbons, PFOS exhibits greater hydrophobicity due to two major structural differences: firstly, it has one extra CF₂ unit and secondly, the sulfonate group in PFOS, being a relatively hard base, readily adsorbs on oxide surfaces, enhancing its adsorption compared to the carboxylate group in PFOA. While comparing activated carbon (AC) adsorption performance, powdered activated carbon (PAC) demonstrates higher adsorption capacity than granular activated carbon (GAC) for PFOS and PFOA. Anion exchange resin (AER) outperforms other adsorbents, with a maximum adsorption capacity for PFOS twice that of PFOA. Carbon nanotubes (CNTs) exhibit two-fold higher adsorption for PFOS compared to PFOA, with single-walled CNTs showing a distinct advantage. Overall, the removal of PFOS and PFOA under similar conditions on different adsorbents is observed to be in the following order: AER > single-walled CNTs > AC. Moreover, AER, single-walled CNTs, and AC exhibited higher adsorption capacities for PFOS than PFOA. In situ remediation studies of PFOA/S-contaminated soil using colloidal activated carbon show a reduction in concentration to below acceptable limits within 12–24 months. The theoretical and experimental studies cited in this review highlight the role of air–water interfacial adsorption in retaining PFOA and PFOS as a function of their charged head groups during their transport in unsaturated porous media. Full article

Triiodide resin has an antimicrobial effect on bacteria in water. In the traditional TR manufacturing method, potassium iodide (KI) and crystalline I₂ are reacted to form triiodide ion (I₃⁻). However, I₂ is difficult to use and store because it is vaporizable and poorly soluble in water. This study was conducted to develop a method of producing triiodide resin (TR) without using crystalline I₂. A chemical radical reaction between a commercially available peracetic acid (PAA) solution and a potassium iodide (KI) solution was used to produce I₂ and I₃⁻ ions, which combined with a strong basic anion exchange resin to produce TR. The disinfection of pathogenic microorganisms (e.g., Escherichia coli, Salmonella spp.) present in anaerobically digested livestock wastewater is essential prior to its discharge into public water systems or marine environments, in order to safeguard environmental integrity and public health. Anaerobically treated contaminated livestock wastewater was sterilized through three rounds of treatment with a TR column and prepared by the oxidation of a 100 mM KI solution. Full article