Search Results (555)

A metal-ion-free method was developed to prepare κ-carrageenan/cellulose hydrogel beads for efficient cationic dye removal. The beads were fabricated using a mixture of 1-ethyl-3-methylimidazolium acetate and N,N-dimethylformamide as the solvent system, followed by aqueous ethanol-induced phase separation. This process eliminated the need for metal-ion crosslinkers, which typically neutralize anionic sulfate groups in κ-carrageenan, thereby preserving a high density of accessible binding sites. The resulting beads formed robust interpenetrating polymer networks. The initial swelling ratio reached up to 28.3 g/g, and even after drying, the adsorption capacity remained over 50% of the original. The maximum adsorption capacity for crystal violet was 241 mg/g, increasing proportionally with κ-carrageenan content due to the higher surface concentration of anionic sulfate groups. Kinetic and isotherm analyses revealed pseudo-second-order and Langmuir-type monolayer adsorption, respectively, while thermodynamic parameters indicated that the process was spontaneous and exothermic. The beads retained structural integrity and adsorption performance across pH 3–9 and maintained over 90% of their capacity after five reuse cycles. These findings demonstrate that κ-carrageenan/cellulose hydrogel beads prepared via a metal-ion-free strategy offer a sustainable and effective platform for cationic dye removal from wastewater, with potential for heavy metal ion adsorption. Full article

The discharge of oily wastewater threatens the ecosystem and human health, and the efficient treatment of oily wastewater is confronted with problems of high mass transfer resistance at the oil-water-solid multiphase interface, significant light shielding effect, and easy deactivation of photocatalysts. Although traditional physical separation methods avoid secondary pollution by chemicals and can effectively separate floating oil and dispersed oil, they are ineffective in removing emulsified oil with small particle sizes. To address these complex challenges, photocatalytic technology and photocatalysis-based improved technologies have emerged, offering significant application prospects in degrading organic pollutants in oily wastewater as an environmentally friendly oxidation technology. In this paper, the degradation mechanism, kinetic mechanism, and limitations of conventional photocatalysis technology are briefly discussed. Subsequently, the surface interface modulation functions of metal doping and heterojunction energy band engineering, along with their applications in enhancing the light absorption range and carrier separation efficiency, are reviewed. Focus on typical studies on the separation and degradation of aqueous and oily phases using photocatalytic membrane technology, and illustrate the advantages and mechanisms of photocatalysts loaded on the membranes. Finally, other new approaches and converging technologies in the field are outlined, and the challenges and prospects for the future treatment of oily wastewater are presented. Full article

Oral delivery of hydrophobic compounds remains challenging due to their poor aqueous solubility and the potential toxicity associated with conventional surfactant-based emulsions. To address these issues, we present a surfactant-free encapsulation strategy using electrosprayed alginate hydrogel beads for the stable and controlled delivery of hydrophobic oils. Hydrophobic compounds were dispersed in high-viscosity alginate solutions without surfactants via ultrasonication, forming kinetically stable oil-in-water dispersions. These mixtures were electrosprayed into calcium chloride baths, yielding monodisperse hydrogel beads. Higher alginate concentrations improved droplet sphericity and suppressed phase separation by enhancing matrix viscosity. The resulting beads exhibited stimuli-responsive degradation and controlled release behavior in response to physiological ionic strength. Dense alginate networks delayed ion exchange and prolonged structural integrity, while elevated external ionic conditions triggered rapid disintegration and immediate payload release. This simple and scalable system offers a biocompatible platform for the oral delivery of lipophilic active compounds without the need for surfactants or complex fabrication steps. Full article

Background/Objectives: We developed and validated a robust and simple LC–MS/MS method for the simultaneous quantification of amoxicillin and clavulanate in human plasma relative to previously reported methods. Methods: Amoxicillin; clavulanate; and an internal standard, 4-hydroxytolbutamide, in human K₂-EDTA plasma, were deproteinized with acetonitrile and then subjected to back-extraction using distilled water–dichloromethane. Separation was performed on a Poroshell 120 EC-C₁₈ column with a mobile-phase gradient comprising 0.1% aqueous formic acid and acetonitrile at a flow rate of 0.5 mL/min within 6.5 min. The negative electrospray ionization modes were utilized to monitor the transitions of m/z 363.9→223.1 (amoxicillin), m/z 198.0→135.8 (clavulanate), and m/z 285.0→185.8 (4-hydroxytolbutamide). Results/Conclusions: Calibration curves exhibited linear ranges of 10–15,000 ng/mL for amoxicillin (r ≥ 0.9945) and 20–10,000 ng/mL for clavulanate (r ≥ 0.9959). Intra- and inter-day’s coefficients of variation, indicating the precision of the assay, were ≤7.08% for amoxicillin and ≤10.7% for clavulanate, and relative errors in accuracy ranged from −1.26% to 10.9% for amoxicillin and from −4.41% to 8.73% for clavulanate. All other validation results met regulatory criteria. Partial validation in lithium–heparin, sodium–heparin, and K₃-EDTA plasma confirmed applicability in multicenter or large-scale studies. This assay demonstrated itself to be environmentally friendly, as assessed by the Analytical GREEnness (AGREE) tool, and was successfully applied to a clinical pharmacokinetic study of an Augmentin^® IR tablet (250/125 mg). The inter-individual variabilities in clavulanate exposures (AUC_t and C_max) were significantly greater than in amoxicillin, and they may inform the clinical design of future drug–drug interaction. Full article

This study proposes a simple yet versatile microfluidic strategy for fabricating monodisperse alginate hydrogel microspheres using a symmetric flow-focusing device. The system integrates three key innovations: (1) Cost-effective mold fabrication: A paper-based positive master replaces conventional SU-8 photoresist, significantly simplifying device prototyping. (2) Surfactant-free droplet generation: Alginate hydrogel droplets are formed at the first flow-focusing junction without requiring interfacial stabilizers. (3) In situ solidification with coalescence suppression: Acetic acid-infused corn oil is introduced at the adjacent junction, simultaneously triggering ionic crosslinking of alginate via pH reduction while preventing droplet aggregation. Notably, the hydrogel microspheres can be efficiently harvested through oscillatory aqueous phase separation, removing post-fabrication washing steps (typically 6–8 cycles for surfactant and oil removal). This integrated approach demonstrates exceptional advantages in fabrication simplicity, process scalability, and operational robustness for high-throughput hydrogel microsphere production. Full article

The limited understanding of intermolecular interactions in deep eutectic solvents (DESs) has restricted their rational design and broader application. In this study, a series of hydrophobic DESs (HDESs) were prepared using lidocaine as the hydrogen bond acceptor and various carboxylic acids as hydrogen bond donors. Their physicochemical properties, including density, viscosity, and thermal stability, were systematically characterized. Interactions between components were evaluated through excess molar volume, viscosity deviation, and Grunberg–Nissan parameters. Strong hydrogen bonding between lidocaine and carboxylic acids was confirmed, which weakened with increasing alkyl chain length of the acids. Furthermore, as the acid content in the mixture increased, lidocaine’s ability to disrupt the intrinsic hydrogen-bonding network of the carboxylic acids decreased, thereby weakening the hydrogen bonding interactions between the components. The extraction capability of the HDESs for cobalt ions was evaluated in aqueous systems. Cobalt, a key material in lithium-ion batteries and advanced alloys, is in rising demand due to clean energy development. The lidocaine/decanoic acid (1:2) system exhibited nearly 100% extraction efficiency, surpassing conventional extractants. The hydrophobic nature of the HDESs facilitated effective phase separation and reduced solvent loss. These findings provide theoretical insights and design principles for developing high performance HDESs tailored for environmentally friendly metal recovery, particularly in battery recycling and treatment of industrial wastewater. Full article

Produced water is the waste aqueous phase from petroleum extraction. As it contains salts, a high organic load, and toxic organic compounds, it should be treated before disposal or reuse. In this research, the combination of membrane processes (microfiltration or membrane distillation) with TiO₂-based heterogeneous photocatalysis was assessed to treat synthetic produced water. Pre-treatment with both microfiltration and membrane distillation removed the majority (90–98%) of large organic compounds (humic acids) from produced water. Moreover, membrane distillation also eliminated salt (sodium chloride). However, membrane processes only removed 10–50% of phenol, used here as proxy for low-molecular-weight toxic organic compounds. For this reason, membrane permeates, from microfiltration and membrane distillation, underwent a further photocatalytic treatment aimed at phenol degradation. The application of TiO₂ photocatalysis to membrane distillation permeates was successful (100% phenol removal in 5 min), while the high chloride concentration of microfiltration permeates acted as inhibitor of the photocatalytic process. Overall, good-quality water may be obtained from the combination of membrane distillation and heterogeneous photocatalysis, which performed much better than the two techniques used separately. Indeed, while membrane distillation was not able to remove phenol, produced water was too complex a matrix to be effectively treated with TiO₂/UV photocatalysis alone. Full article

The growing energy demand has emphasized the importance of developing nuclear technologies and high-purity lithium isotopes (⁶Li and ⁷Li) as raw materials. This study investigates how voltage and migration time affect two types of low-density polyethylene membranes—one impregnated with ionic liquids and the other non-impregnated—for lithium isotope separation via electromigration from a lithium-loaded organic phase to an aqueous solution. We developed a laboratory-made setup for high-precision lithium isotope measurements (2RSD = ±0.30‰) of natural carbonate samples (LSVEC) and an optimized protocol for isotope ratio measurements using quadrupole ICP-MS with the sample-standard bracketing method (SSB). The results document that both impregnated and non-impregnated membranes can achieve promising ⁶Li enrichment under different environmental conditions, including ionic liquids and organic solutions in the cathode chamber. Lithium-ion mobility is influenced by voltage in an environment assisted by 0.1 mol/L tetrabutylammonium perchlorate and increases quasi-linearly from 5 to 15 V. Between 20 and 25 h, the lithium-ion concentration had the maximum value, after which the trend declined. In the BayesGLM model, we incorporated all data and systematically eliminated those with a low enrichment factor, either individually or in groups. Our findings indicated that the model was not significantly affected by the exclusion of measurements with low α. This suggests that voltage and migration time are crucial, and achieving a better enrichment factor depends on applying the optimal ratio of ionic liquids, crown ethers, and organic solvents. Ionic liquids used for impregnation sustain enrichment in the first hours, particularly for ⁷Li; however, after 25 h, ⁶Li demonstrated a higher enrichment capacity. The maximum single-stage separation factor for ⁶Li/⁷Li was achieved at 24 and 48 h for an impregnated membrane M2 (α = 1.021/1.029) and a non-impregnated membrane M5 (α = 1.031/1.038). Full article

Activated carbon is a useful adsorbent for the removal of pollutants from the aqueous phase. In this study, an easy method to overcome the difficulty in separating activated carbon from a solution after adsorption has been developed. Cellulose-activated carbon gels with a high activated carbon content up to 70% in the total solids were successfully prepared via the dissolution–regeneration process of cellulose using a LiBr aqueous solution. Activated carbon suspended in a cellulose solution dissolved by heating with a LiBr aqueous solution was embedded into a gel directly formed by lowering the temperature of the cellulose solution. The cellulose-activated carbon gels exhibited large specific surface areas and sufficient mechanical properties. The adsorption capacity of methylene blue onto the cellulose-activated carbon gels proportionally increased with the increasing content of activated carbon. The cellulose-activated carbon gels maintained a high adsorption capacity even after repeated adsorption–desorption cycles, demonstrating their potential as reusable adsorbents. Full article

This study investigates pegmatites with exceptionally rare mineralogical and chemical signatures, hosted by the 1.8 Ga peralkaline albite-enriched granite, which corresponds to the renowned Madeira Sn-Nb-Ta-F (REE, Th, U) deposit in Pitinga, Brazil. Four distinct pegmatite types are identified: border pegmatites, pegmatitic albite-enriched granite, miarolitic pegmatite, and pegmatite veins. The host rock itself has served as the source for the fluids that gave rise to all these pegmatites. Their mineral assemblages mirror the rare-metal-rich paragenesis of the host rock, including pyrochlore, cassiterite, riebeckite, polylithionite, zircon, thorite, xenotime, gagarinite-(Y), genthelvite, and cryolite. These pegmatites formed at the same crustal level as the host granite and record a progressive magmatic–hydrothermal evolution driven by various physicochemical processes, including tectonic decompressing, extreme fractionation, melt–melt immiscibility, and internal fluid exsolution. Border pegmatites crystallized early from a F-poor, K-Ca-Sr-Zr-Y-HREE-rich fluid exsolved during solidification of the pluton’s border and were emplaced in contraction fractures between the pluton and country rocks. Continued crystallization toward the pluton’s core produced a highly fractionated melt enriched in Sn, Nb, Ta, Rb, HREE, U, Th, and other HFSE, forming pegmatitic albite-enriched granite within centimetric fractures. A subsequent pressure quench—likely induced by reverse faulting—triggered the separation of a supercritical melt, further enriched in rare metals, which migrated into fractures and cavities to form amphibole-rich pegmatite veins and miarolitic pegmatites. A key process in this evolution was melt–melt immiscibility, which led to the partitioning of alkalis between two phases: a K-F-rich aluminosilicate melt (low in H₂O), enriched in Y, Li, Be, and Zn; and a Na-F-rich aqueous melt (low in SiO₂). These immiscible melts crystallized polylithionite-rich and cryolite-rich pegmatite veins, respectively. The magmatic–hydrothermal transition occurred independently in each pegmatite body upon H₂O saturation, with the hydrothermal fluid composition controlled by the local degree of melt fractionation. These highly F-rich exsolved fluids caused intense autometasomatic alteration and secondary mineralization. The exceptional F content (up to 35 wt.% F in pegmatite veins), played a central role in concentrating strategic and critical metals such as Nb, Ta, REEs (notably HREE), Li, and Be. These findings establish the Madeira system as a reference for rare-metal magmatic–hydrothermal evolution in peralkaline granites. Full article

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary phase (hydrophobic stationary phase, C18 and strong cation exchanger (SCX)) was our first choice. Design of Experiments (DoE) was used to estimate how various factors such as pH, mobile phase composition and flow rate influenced chromatographic performance. As a result, the separation was achieved in 24 min using an aqueous phosphate buffer phase (pH 7.20) and 20 mM triethylamine, with methanol being used as organic modifier (30%). Their retention mechanism was investigated. The new method was validated in term of linearity, limits of detection and quantification, precision, accuracy, and robustness. The method was applied to river water samples, and good results were obtained. Full article

Excessive Zn(II) ions in aquatic environments pose significant risks to both human health and ecological systems due to their toxic effects, bioaccumulation potential, and interference with essential biological processes. To address this issue, a novel analcime@calcium aluminate@polyethylene glycol 400 (ACP) nanocomposite was fabricated using the hydrothermal technique, alongside an analcime@calcium aluminate (AC) nanocomposite for the efficient elimination of Zn(II) ions from aqueous media. X-ray diffraction (XRD) analysis affirmed the successful formation of crystalline phases, revealing average crystallite sizes of 72.93 nm for AC and 63.60 nm for ACP. Energy-dispersive X-ray spectroscopy (EDX) confirmed the elemental composition of the nanocomposites, showing that AC primarily contained oxygen, sodium, aluminum, silicon, and calcium, whereas ACP incorporated 19.3% carbon due to the polyethylene glycol 400. Field emission scanning electron microscopy (FE-SEM) revealed that AC exhibited hexagonal and platelet-like structures, whereas ACP displayed more dispersed and layered morphologies. High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of stacked platelet-like structures in AC and more defined, separated nanosheets in ACP. The maximum adsorption capacities of AC and ACP were 149.93 and 230.95 mg/g, respectively. The adsorption pathway of Zn(II) ions onto ACP nanocomposite involved three primary interactions: electrostatic attraction facilitated by calcium aluminate, ion exchange provided by analcime, and complexation promoted by polyethylene glycol 400. Thermodynamic analysis indicated that the adsorption process was exothermic, spontaneous, and primarily chemical in nature. Kinetic modeling confirmed that adsorption followed the pseudo-second-order model, while isotherm studies demonstrated adherence to the Langmuir model, indicating monolayer adsorption on homogeneous sites. Full article

Background: Antimicrobial resistance (AMR) represents a critical global health challenge, requiring innovative strategies to combat resistant bacterial strains. Cymbopogon essential oils (EOs) are promising natural antimicrobial agents. Methods: The EO of Cymbopogon commutatus was extracted by hydrodistillation from fresh aerial parts and compared to commercial EOs from C. citratus, C. nardus, and C. winterianus. Antibacterial activity was evaluated against seven bacterial strains (two Gram-positive and five Gram-negative). Both water-soluble fractions and liposome-encapsulated formulations were tested. Liposomes were prepared using soybean lecithin, and their stability was assessed by dynamic light scattering (DLS). The chemical composition of the pure EOs, water-soluble fractions and non-water-soluble fractions was analyzed by gas chromatography–mass spectrometry (GC-MS). Results: Liposome encapsulation improved EO solubility in aqueous media and significantly enhanced antibacterial efficacy, reducing minimum inhibitory concentration (MIC) values compared to the water-soluble fractions (MICs ≥ 25%). Among the tested formulations, the liposome containing C. citratus EO exhibited the strongest inhibitory effect against Staphylococcus aureus (MIC: 0.04%) followed by liposomes with C. nardus and C. commutatus (MIC: 0.08%). Against Enterococcus faecalis, the most effective formulation was the liposome containing C. winterianus EO (MIC: 0.02%), followed by C. citratus (MIC: 0.08%). The liposome formulated with C. winterianus maintained its particle size over 72 h without phase separation. GC-MS analysis revealed distinct phytochemical profiles: C. commutatus EO was rich in piperitone (73.9%) and C. citratus was rich in (Z)-(3,3-Dimethyl)-cyclohexylideneacetaldehyde (39.9%) and citral (32.5%), while C. nardus and C. winterianus were dominated by geraniol (21.5%) and citronellal (30.8%), respectively. Notably, piperitone, the major compound in C. commutatus EO, exhibited strong antibacterial activity against S. aureus (MIC of <0.04%). Conclusions: These findings support the potential of liposome-encapsulated Cymbopogon EOs as an effective and sustainable strategy to address AMR. This study provides a foundation for the development of plant-based antimicrobial formulations with improved efficacy. Full article

Industrial wastewater poses a significant environmental challenge due to its harmful effects. The development of sustainable membrane processes for water treatment and the environmentally friendly production of polymer membranes is one of the major challenges of our time. An alternative approach is to prepare polyelectrolyte complex (PEC) membranes using the aqueous phase separation (APS) method without the use of toxic solvents. In this work, PEC nanofiltration membranes of poly(sodium-p-styrenesulfonate) (PSS)/polyethylenimine (PEI) modified with carbon nanoparticles (graphene oxide, polyhydroxylated fullerene (HF), multi-walled carbon nanotubes) were developed for enhanced water treatment from anionic food dyes and heavy metal ions. The effect of varying the PSS/PEI monomer ratio, carbon nanoparticles, the content of the optimal HF modifier, and the cross-linking agent on the membrane properties was studied in detail. The changes in the structure and physicochemical properties of the PEC-based membranes were investigated using spectroscopic, microscopic, thermogravimetric analysis methods, and contact angle measurements. The PSS and PEI interactions during PEC formation and the effect of PEI protonation on membrane properties were investigated using computational methods. The optimal cross-linked PEC/HF(1%) (1:1.75 PSS/PEI) membrane had more than 2 times higher permeability compared to the pristine PEC membrane, with dye and heavy metal ion rejection of 99.99 and >97%, respectively. Full article

The effects of a series of sodium salts (Na₃PO₄, Na₂CO₃, Na₂SO₄, Na₂SO₃, Na₂MO₄, Na₂CrO₄, and Na₂WO₄) on the phase separation of poly(ethylene glycol) (PEG) solutions in water at PEG concentrations of 0.5 to 30 wt.% were studied. The salts’ effects on phase separation are found to correlate with the change in the entropy related to the structural changes in water during anion hydration. The same salts’ effects on phase separation in aqueous solutions of branched PEG and polyvinylpyrrolidone at a polymer concentration of 10 wt.% were also examined. The results obtained support the assumption that phase separation in aqueous polymer–salt systems is an entropy-driven process. Full article