Search Results (406)

This study introduces a novel hybrid model for an electromembrane stack, unifying an equivalent electrical circuit model incorporating specific resistance ($R_M,R_s$) and capacitance ($C_{gs},C_{dl}$) parameters with an empirical fouling model in a single framework. The model simplifies the traditional approach by serially connecting N ($N=10$) ion exchange membranes (anionic PC-SA and cationic PC-SK) and is validated using $NaCl$ and $N{a}_{2}S{O}_4$ solutions in comparison with laboratory tests using various voltage signals, including direct current and electrically pulsed reversal operations at frequencies of 2000 and 4000 Hz. The model specifically accounts for the chemical stratification of the cell unit into bulk solution, diffusion, and Stern layers. We also included a calibration method using correction factors (${\alpha }_i$) to fine-tune the electrical current signals induced by voltage stimulation. The empirical component of the model uses experimental data to simulate membrane fouling, ensuring consistency with laboratory-scale desalination processes performed under pulsed reversal operations and achieving a prediction error of less than 10%. In addition, a comparative analysis was used to assess the increase in electrical resistance due to fouling. By integrating electronic and empirical electrochemical data, this hybrid model opens the way to the construction of simple, practical, and reliable models that complement theoretical approaches, signifying an advance for a variety of electromembrane-based technologies. Full article

Dialdehyde crosslinked poly aspartate/alginate hydrogel beads were synthesized by covalently introducing poly aspartate into the alginate network via dialdehyde-mediated crosslinking, and the resulting effects on swelling and adsorption behavior were investigated. Alginate was partially oxidized to form dialdehyde alginate and crosslinked with poly aspartic acid via Schiff base formation, followed by ionic crosslinking with calcium ions. The chemical structure and morphology of the gel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Incorporation of PAsp significantly altered the swelling behavior of alginate-based gel beads. In saline solution, PAsp-modified gel beads exhibited a swelling ratio of approximately 112 g/g, which was higher than that of calcium alginate gel beads. This behavior is suggested to be associated with changes in the alginate–calcium network structure induced by polymer modification. PAsp-modified gel beads exhibited moderate but distinct adsorption behavior depending on the adsorbate. Removal efficiencies of approximately 40–50% were observed for copper and cobalt ions, while a removal efficiency of around 50% was obtained for the cationic dye crystal violet. In contrast, adsorption of the anionic dye Congo red decreased with increasing PAsp content, indicating charge-dependent adsorption behavior. Overall, this study demonstrates that PAsp modification via dialdehyde-mediated crosslinking influences both the swelling and adsorption properties of alginate-based hydrogel beads. The results provide fundamental insight into how network modification can be used to tune the behavior of alginate-based hydrogels in aqueous environments. Full article

BO₃³⁻, PO₄³⁻, and SO₄²⁻ anionic groups were used to study their effects on the structure and luminescence of Sm³⁺-doped ZnO. ZnO, ZnO:Sm³⁺, ZnO, Zn₄B₆O₁₃:Sm³⁺, and Zn₂P₂O₇:Sm³⁺ phosphors were successfully synthesized via combustion synthesis. While BO₃³⁻ and PO₄³⁻ ions led to the formation of new crystalline phases, the sulfate precursor decomposed during synthesis, yielding ZnO with only minor surface sulfur traces. The XRD results revealed the formation of wurtzite crystal structures in the ZnO, ZnO:Sm³⁺, and ZnO-SO₄:Sm³⁺ samples, while a complete change of structure was observed after the incorporation of borate (BO₃³⁻) and phosphate (PO₄³⁻) ions into ZnO:Sm³⁺ to Zn₄B₆O₁₃:Sm³⁺ and Zn₂P₂O₇:Sm³⁺, respectively. The structures for borate and phosphate ions were confirmed as cubic (Zn₄B₆O₁₃) and monoclinic (Zn₂P₂O₇) crystal structures, respectively. The morphological studies of ZnO:Sm³⁺ and ZnO-SO₄:Sm³⁺ were characterized by aggregated particles with different shapes and sizes. Zn₄B₆O₁₃ and Zn₂P₂O₇ samples were characterized by having cubic and rough surfaces, respectively. The oxidation state of the Sm ions was confirmed by XPS analysis. The photoluminescence studies revealed a broad-band emission for the ZnO:Sm³⁺ and ZnO-SO₄:Sm³⁺ materials and characteristic Sm³⁺ emissions (from the ⁴G_5/2 level to lower states ⁶H_J (J = 5/2, 7/2, 9/2, and 11/2)) for the Zn₄B₆O₁₃ and Zn₂P₂O₇ samples. Enhanced emissions were observed after the incorporation of anionic group systems. The most intense PL emission was observed from the Zn₄B₆O₁₃ phosphor material. The CIE calculations revealed that the best color purity results were from Zn₄B₆O₁₃, which lay in the orange region with 98% color purity. Full article

In bipolar membrane electrodialysis (BPED), proton transport through the anion-exchange membrane (AEM) is a major factor that reduces overall process efficiency. In this study, we propose a composite AEM incorporating a proton-blocking layer that combines strongly basic and weakly basic functional groups on top of a strongly basic AEM, providing proton-blocking capability while minimizing degradation of membrane conductivity. The proton-blocking layer is prepared by reacting brominated poly(phenylene oxide) (BPPO) with diamines having different alkyl chain lengths, namely N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHDA), N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA), and N,N,N′,N′-tetramethylethylenediamine (TMEDA). When TMHDA, which has the longest alkyl chain, is introduced into PPO, the resulting membrane exhibits high conductivity but low proton-blocking performance. In contrast, when TMEDA, which has the shortest alkyl chain, is introduced, the membrane shows low conductivity and high proton-blocking performance. Therefore, the balance between membrane conductivity and proton-blocking performance can be optimized by adjusting the molar ratio of the two diamines. The composite AEM prepared with the optimal composition simultaneously demonstrates superior conductivity and proton-blocking performance compared to the commercial proton-blocking membrane (ACM, Astom Corp., Tokyo, Japan). Furthermore, the application of this membrane has been shown to effectively improve both the energy efficiency and current efficiency of the BPED process for lithium hydroxide recovery. Full article

Background: Resveratrol (3,5,4′-trihydroxy-trans-stilbene, RVT) is one of the most extensively studied natural polyphenols, with numerous health benefits documented in the literature. One of its most characterized biological properties is the strong antioxidant capacity. However, its poor biopharmaceutical properties limit its in vivo applicability. In this study, we conducted a detailed comparative analysis of the antioxidant and protective capacity of pure and loaded into Pluronic micelles resveratrol. Methods: Various in vitro antioxidant assays, such as DPPH, ABTS, superoxide anion radical scavenging, ferric (FRAP), and copper-reducing power assay (CUPPRAC), and iron-induced lipid peroxidation were performed. In addition, the in vitro 6-OHDA model of neurotoxicity in brain synaptosomes and the in vivo scopolamine (Sco)-induced model of cognitive impairment in rats were also employed. The main antioxidant biomarkers—the levels of lipid peroxidation (LPO) and total glutathione (GSH), as well as activities of superoxide dismutase, catalase, and glutathione peroxidase—were measured in the cortex and hippocampus. Results: The results from the in vitro tests demonstrated better ferric-reducing power activity and better neuroprotective capacity of the micellar resveratrol (mRVT), as evidenced by preserved synaptosomal viability and maintained GSH levels in a concentration-dependent manner in 6-OHDA-induced neurotoxicity. Regarding the in vivo results, mRVT (10 µM concentration) was the most effective treatment in supporting recognition memory formation in dementia rats. Further, mRVT demonstrated better LPO protective capacity in the hippocampus and GSH preserving activity in the cortex than the pure drug. Conclusions: The incorporation of resveratrol in polymeric micelles could enhance its antioxidant and neuroprotective effects. Full article

The use of seawater in mineral processing poses significant challenges for solid–liquid separation, including polymer chain contraction, accelerated coagulation, and brittle aggregate formation. This study evaluates the impact of fractional dosing of anionic polyacrylamide (PAM) on the formation, structure, and sedimentation performance of flocs in quartz-kaolinite suspensions prepared in seawater. Four dosing schemes (1, 2, 3, and 4 pulses) were analyzed, maintaining a total dose of 15 g/t and flocculation times of 75, 90, and 105 s. Sedimentation assays, kinetic monitoring using FBRM, size distributions, fractal dimensions, and bulk density were integrated to characterize the aggregation process. The results show that all fractional strategies outperform single-pulse dosing, with the three-pulse scheme (0–30–60 s) standing out, achieving the highest settling rates, the most significant fines reduction, and the best structural robustness. FBRM kinetics reveal stepped growth, less shear breakage, and more stable maturation when polymer addition is divided temporally. Consistently, fractal dimension and aggregate density reach their maximum values after three 90 s pulses, indicating more compact, less porous structures. Zeta potential analysis confirms a strong polymer-particle interaction in kaolinite under high salinity. The superior performance of the multi-pulse strategy is explained by the progressive availability of active polymer segments during aggregate formation and maturation. Each pulse is incorporated into a partially structured suspension, in which unoccupied mineral surfaces and flocs from the early stages of consolidation still exist. This staggered adsorption avoids local overdosing associated with flash injections, improves bridging efficiency, reduces brittle aggregate formation, and promotes more uniform restructuring. Full article

Hazardous galvanic sludge waste (GSW) from the electroplating industry, produced at 100,000–150,000 tonnes/year in the EU and containing high concentrations of Cr and Ni was successfully treated using metakaolin-based geopolymers via Stabilization/Solidification (S/S). The experimental design incorporated chelating (sodium diethyl dithio carbamate, C₅H₁₀NS₂Na, DTC), reducing (sodium sulfide, Na₂S), and adsorbing (hydroxyapatite, Ca₅(PO₄)₃(OH), Hap) agents separately to improve heavy metal immobilization. The results demonstrated that Na₂S drastically decreased Cr release by −98.7% by reducing mobile Cr(VI) to insoluble Cr(III). DTC reduced Ni leaching by −93.4%, forming sparingly soluble Ni(II)(DTC)₂ complexes that precipitated within the matrix. Hap enhanced Ni retention by 55.5% via cation exchange but was ineffective for Cr due to electrostatic repulsion with the anion Cr(VI)O₄²⁻ at the geopolymer’s high pH. This work is the first to apply geopolymerization coupled with these chemical agents for S/S of as-received galvanic waste, offering a highly efficient, low-carbon strategy to manage this hazardous industrial residue. Full article

This study explores the sol–gel synthesis, structural characterization, and photocatalytic performance of Ho³⁺-doped TiO₂ nanopowders at two dopant levels (0.5 and 2 mol%). Transparent, homogeneous gels were prepared using titanium (IV) butoxide and holmium (III) nitrate pentahydrate in ethanol, followed by drying and optional annealing at 500 °C. X-ray diffraction confirmed anatase TiO₂ as the dominant crystalline phase, with Ho incorporation suppressing crystal growth and yielding smaller crystallite sizes than undoped TiO₂. FT-IR and UV-Vis spectroscopy verified complete hydrolysis–condensation during gel formation, while diffuse reflectance spectra revealed a red-shifted absorption edge, indicating reduced band gaps. SEM analysis showed nanoscale particles with agglomeration, which intensified after annealing. Photocatalytic activity was tested under UV irradiation using Crystal Violet (anionic dye) and Carmoisine (cationic dye). Annealed Ho-doped powders exhibited markedly higher degradation rates, with the 2 mol% sample achieving the greatest efficiency, particularly against Crystal Violet. These findings demonstrate that Ho³⁺ doping enhances TiO₂’s UV-driven photocatalytic activity by tailoring its structural and optical properties. Full article

Water pollution from textile effluents poses serious environmental risks, particularly due to persistent anionic dyes such as Reactive Black 5 (RB5). This study demonstrates that simple deposition of Y₂O₃ onto commercially available, biobased TiO₂ (bTiO₂) significantly enhances photocatalytic degradation efficiency under simulated sunlight, suppressing rapid recombination of electron–hole pairs. Addressing a key research gap, the proposed method replaces expensive nanoscale precursors and complex synthesis routes typically used for Y₂O₃/TiO₂ systems with a low-cost, straightforward approach involving weak complexation and co-precipitation. The resulting Y₂O₃-bTiO₂ composite was characterized using FTIR, XRD, SEM, EDX, TEM, XPS, and UV-DRS techniques, confirming efficient incorporation of Y₂O₃ on the TiO₂ surface. Photocatalytic experiments revealed that nanoparticles calcined at 700 °C achieved complete RB5 degradation within 60 min—reducing the reaction time by half compared to undoped bTiO₂. Systematic studies of initial dye concentration, catalyst loading, and irradiation time confirmed that the degradation followed pseudo-first-order kinetics with a rate constant of 0.064 min⁻¹ (R² = 0.98). Calculated quantum yields corroborated the reduced electron–hole recombination induced by Y₂O₃ deposition. These findings highlight the novelty and practicality of the developed Y₂O₃-bTiO₂ photocatalyst as an efficient, affordable, and environmentally sustainable material for the degradation of industrial dyes. Full article

Sodium alginate (SA) is widely used as an edible coating for fruit preservation, but its weak water barrier and antibacterial properties limit broader application. In this study, quaternary ammonium lignin–cinnamaldehyde (QKC) composite particles were incorporated into SA as multifunctional fillers to construct antibacterial coatings. Electrostatic and hydrogen-bonding interactions between cationic QKC and anionic SA yielded a uniform, stable network with improved hydrophobicity and UV-shielding capacity. At 5 wt% QKC loading (SA5), the tensile strength increased from 11.53 to 24.42 MPa (111.8% higher than SA0), while water vapor permeability decreased by 35.4%. SA coatings also exhibited strong antioxidant activity, and the ABTS radical scavenging rate increased to 70.22% at 7 wt% QKC, with SA5 offering a favorable balance between antioxidant, barrier, and mechanical properties. SA5 showed pronounced antibacterial efficacy, giving inhibition rates of 96% against Staphylococcus aureus and 65% against Escherichia coli. Coating trials on persimmons and tangerines demonstrated that SA5 reduced weight loss, delayed firmness decline, and mitigated decay during storage. In addition, calcium-crosslinked SA/QKC hydrogel beads markedly delayed visible mold growth on blueberries. These results indicate that QKC-reinforced SA coatings provide a promising strategy for enhancing the postharvest quality and shelf life of fresh fruit. Full article

The cell-penetrating peptide Pep-1 interacts with lipid membranes through combined electrostatic and hydrophobic forces, yet the structural details of its membrane remodeling activity remain unclear. Using atomic force microscopy (AFM), we examined how Pep-1 perturbs supported lipid bilayers of varying composition and geometry. In zwitterionic POPC bilayer patches, Pep-1 preferentially targeted patch boundaries, where lipid packing is less constrained, leading to edge erosion and detergent-like disintegration. Incorporation of anionic POPS enhanced peptide binding and localized disruption, giving rise to elevated annular rims, holes, and peptide–lipid aggregates. In cholesterol-containing POPC bilayer patches, Pep-1 induced extensive surface reorganization marked by protruded, ridge-like features, consistent with lipid redistribution and curvature generation. In continuous POPC/POPS bilayers lacking free edges, Pep-1 formed discrete, flower-like protrusions that coalesced into an interconnected network of thickened peptide-rich domains. These findings reveal composition-dependent remodeling pathways in which Pep-1 destabilizes, reorganizes, or curves membranes according to their mechanical and electrostatic properties, providing new insight into peptide–membrane interactions relevant to cell-penetrating peptide translocation. Full article

1-Butyl-3-methylimidazolium (bmim) ionic liquids (ILs) are widely used for lignocellulose fractionation, yet their role extends beyond mere solvents. This study revealed that bmim-based ILs act as active chemical reagents, modifying the lignin structure in an anion-dependent manner. Thermal treatment (80–150 °C) of spruce dioxane lignin with [bmim]OAc, [bmim]Cl, and [bmim]MeSO₄ resulted in two distinct transformation pathways. In [bmim]MeSO₄, acidic catalysis dominates, leading to lignin condensation (increase in weight-average molecular weight, M_w, to 15.2 kDa at 150 °C) and intense sulfur incorporation (up to 9.9%) via anion-derived methylation/sulfation. Conversely, [bmim]OAc promotes depolymerization (decrease in M_w to 3.6 kDa) and efficient covalent bonding of the bmim cation to lignin (up to 10.8 cations per 100 aromatic units and a 6.5% nitrogen content at 150 °C), preventing condensation. Two-dimensional NMR and HPLC-HRMS analyses revealed the formation of a C–C bond between the C₂ atom of the imidazole ring and the α-carbon of the phenylpropane lignin fragments and allowed for the identification of a number of individual nitrogen-containing lignin oligomers in the [bmim]OAc-treated samples. Their formation likely proceeds via nucleophilic addition of the N-heterocyclic carbene (NHC), derived from the bmim cation by deprotonation with the highly basic acetate anion, to aldehyde groups. The action of [bmim]Cl primarily induces acid-catalyzed transformations of lignin with minimal covalent modification. These findings redefine imidazolium ILs as reactive media in biorefining, where their covalent interactions can influence the properties of lignin but complicate its native structure and the recyclability of the IL. Full article

Al–Si–Cu alloy is one of the aluminum die-cast alloys widely used in industry. Due to the presence of Si and Cu elements in the Al–Si–Cu alloy, the corrosion resistance of the Al–Si–Cu alloy is lowered. Thus, developing a corrosion-resistant film on the Al–Si–Cu alloy is necessary. A layered double hydroxide (LDH) film is recognized as a promising corrosion-resistant coating. LDHs exhibit a distinct structure where positively charged basic layers (metal hydroxides) are interleaved with intermediate layers that accommodate charge-compensating anions and hydration water. The positively charged layers allow for the exchange of anions as interlayers, enabling the incorporation of various anions into the interlayer. The difference in the anion species in the interlayer of the LDH films can affect corrosion-resistant performance. In this study, we aimed to prepare Mg–Al LDH films intercalated with different anions (NO₃⁻, MoO₄²⁻, VO₄³⁻, and PO₄³⁻) and investigate the corrosion resistance of the LDH films. The films were prepared on die-cast Al–Si–Cu alloys using steam coating and immersion processes. The prepared LDH films were characterized by XRD, SEM, FT-IR, and electrochemical measurements. The electrochemical measurements revealed that Mg–Al LDH films intercalated with MoO₄²⁻ showed the most superior corrosion resistance among all films prepared in this study. Full article

This paper presents the results of a numerical simulation of oil displacement from models of terrigenous and cavernous-fractured media using solutions of the anionic surfactant (sodium laureth sulfate). The surfactant concentration was varied from 0 to 0.1 wt.%. The simulations employed a mathematical model for the flow of immiscible liquids based on the VOF method. The model incorporated experimentally measured interfacial tension coefficients and wettability parameters for the surfactant solutions. The results demonstrate that increasing the surfactant concentration enhances the oil displacement coefficient: by 15% for the terrigenous model and by 19% for the cavernous-fractured model compared to water flooding (at 0 wt.% surfactant), achieving a maximum at a concentration of 0.1 wt.%. The influence of potential mechanisms leading to the improved oil displacement coefficient during surfactant solution injection was investigated. It was established that at a fixed displacement rate, the addition of the surfactant causes a local increase in the generalized capillary number by a factor of approximately 3.7. This is identified as the primary mechanism for the observed enhancement of the oil displacement coefficient in this case. The data obtained in this study can be used for further improvement of surfactant flooding technologies for enhanced oil recovery. Full article

Background: The relative merits of the Henderson–Hasselbalch (HH) versus Stewart frameworks for interpreting dialysis-associated acid–base shifts remain debated. Dialysis alters systemic pH through exogenous bicarbonate delivery, chloride displacement, and removal of organic anions. We compared these approaches across hemodialysis (HD) and peritoneal dialysis (PD). Methods: We studied 53 HD patients with paired pre/post-HD blood gas and chemistry (106 observations) and 41 PD patients cross-sectionally, totaling 147 datasets. Derived variables followed the Figge/Stewart implementation [apparent SID (SIDa), effective SID (SIDe), strong ion gap (SIG), albumin-corrected anion gap (AGc)]. For HD, changes in pH (ΔpH) were modeled using HH predictors (ΔHCO₃⁻, ΔPCO₂) and Stewart predictors (ΔSIDa, ΔATOT, ΔPCO₂). For cross-sectional data (pre-HD, post-HD, and PD), HH- and Stewart-based level models were fitted. Stewart-predicted pH was also computed using the Figge and the simplified Constable electroneutrality equation. Results: HD increased pH by 0.11, driven by ΔHCO₃⁻ = +5.7 mΕq/L, ΔCl⁻ = −2.3 mEq/L, and declines in unmeasured anions (ΔSIG = −3.9; ΔAGc = −3.3). SIDa increased only marginally (+1.3 mEq/L), whereas SIDe rose by +5.3 mEq/L and fully tracked the alkalinization. In Δ-models, HH explained 90% of variance in ΔpH (R² = 0.903) compared with 51% for Stewart (R² = 0.514). In level models, HH explained 96% of pH variance versus 36% for Stewart. Bland–Altman analysis showed systematic overestimation of pH by the Figge and Constable approach (bias + 0.111), most pronounced pre-HD. PD patients had consistently higher AGc and SIG values than HD patients, indicating a greater burden of unmeasured anions. Conclusions: Alkalinization during HD is primarily attributable to bicarbonate gain, chloride displacement, and organic-anion clearance. The HH framework provides superior predictive performance for ΔpH, while closed-system Stewart formulations based on SIDa underestimate alkalinization. However, a broader physicochemical interpretation using SIDe and SIG, which incorporate bicarbonate and unmeasured anions, coherently describes the observed physiology. Future applications of the Stewart approach in dialysis should emphasize SIDe and SIG to better reflect the open-system physiology of both HD and PD. Our findings suggest that the HH model remains more predictive of alkalinization, while SIDe and SIG refine the physicochemical understanding. Full article