Search Results (346)

For continuous casting of strong reducing steels, the low-reactive aluminate-based mold flux consisting of CaO-SiO₂-Al₂O₃-CaF₂-Li₂O-B₂O₃-Na₂O with low SiO₂ content was designed. The correlation between the melt structure under high temperature and the crystallization phases during the cooling process and the change of viscosity was analyzed. The following conclusions were obtained. The polymerization degree of the mold flux consistently decreased as the w(CaO)/w(Al₂O₃) ratio increased from 0.93 to 1.65. Due to melt structure depolymerization, the viscosity at 1300 °C dropped from 0.132 Pa·s to 0.054 Pa·s. As the w(CaO)/w(Al₂O₃) ratio increases near the breaking temperature, the crystalline phases in the mold flux transition from LiAlO₂ to Ca₂Al₂SiO₇, and finally to a combination of Ca₁₂Al₁₄O₃₂F₂ and LiAlO₂. The rapid viscosity increase at the breaking temperature was primarily due to the precipitation of these phases. Furthermore, influenced by the changes in crystallization tendency and crystalline phase precipitation, the breaking temperature first decreased and then increased. Increasing the Li₂O mass fraction from 5% to 9% led to a decrease in the polymerization degree of the mold flux. Due to the depolymerizing impact of Li₂O on the slag network, the mold flux viscosity at 1300 °C decreased from 0.102 Pa·s to 0.047 Pa·s. The breaking temperature of the mold flux rose notably with a higher Li₂O mass fraction. At the breaking temperature, the crystalline phases in the mold flux transition from Ca₂Al₂SiO₇ to a combination of LiAlO₂ and Ca₁₂Al₁₄O₃₂F₂. The precipitation of these phases at the breaking temperature directly caused a rapid increase in viscosity. The results systematically reveal the coupling mechanism between melt structure, crystalline phase evolution, and viscosity variation of low-SiO₂ aluminate-based mold flux, which provides an important theoretical basis for composition design and performance regulation of mold fluxes for high-aluminum steel continuous casting. Full article

Phenol (Ph), bisphenol A (BPA), and cresol isomers (o-, m-, p-C) are pollutants widely detected in industrial effluents and resistant to conventional treatment. This study investigated the catalytic potential of manganese peroxidase (MnP), derived from Phanerochaete chrysosporium and expressed in corn, for the removal, via oxidative oligomerization and precipitation, of these compounds from water. Batch experiments were conducted under controlled pH, hydrogen peroxide concentration, and enzyme activity to achieve ≥95% substrate conversion. The optimized MnP system nearly achieved this under stepwise hydrogen peroxide addition. Kinetic analyses revealed short half-lives for initial degradation phases, with BPA and p-C showing near-instantaneous transformation. Mass spectrometry confirmed the formation of soluble and insoluble oligomers (to hexamers for BPA, octamers for p-C, dodecamers for the rest), confirming radical-mediated polymerization pathways. These findings highlight MnP as a robust and eco-friendly biocatalyst for efficient treatment of phenolic pollutants, offering significant potential for integration into advanced wastewater treatment systems. Full article

This experimental study systematically explores the impact of particle size variation in Layered Double Hydroxide (LDH) composites on the thermomechanical and optical properties of poly(methyl methacrylate) (PMMA) nanocomposites. Utilizing a co-precipitation method, LDHs modified with cocamidopropyl betaine (CPB) were synthesized in three distinct sizes (small 80 nm, medium 130 nm, and large 280 nm) and then incorporated into a PMMA matrix through bulk polymerization using Benzoyl Peroxide as the initiator. Morphological analysis via electron microscopy confirmed the exfoliation of LDHs layers within the PMMA matrix, indicating effective dispersion. The medium-sized LDH/PMMA nanocomposite exhibited enhanced interlayer interactions, facilitating polymerization and increasing the thermal degradation onset temperature by 21.2 °C compared to pristine PMMA. In contrast, the small-sized LDH/PMMA nanocomposite demonstrated a significant improvement in mechanical performance, with a 62% increase in storage modulus, attributed to its higher aspect ratio and improved stress transfer. Additionally, the optical transmittance of the nanocomposites across a visible range of 550 nm exceeded 88%, suggesting a minimal impact on optical clarity despite varied particle sizes. Overall, the incorporation of size-specific LDHs modifications led to notable enhancements in both the thermal stability and mechanical performance of the PMMA nanocomposites, underlining the potential of tailored nanoparticle modifications in advanced polymer matrices. Full article

Coagulation-based technologies are increasingly recognized as key for controlling fluoride and hexavalent chromium in urban water and wastewater. Combined geogenic and industrial sources often drive chronic exposure and create an underrecognized public health burden. This review synthesizes current knowledge on the occurrence, speciation, and toxicology of F⁻ and Cr(VI) in urban systems, links regulatory targets to health outcomes, and critically examines conventional, advanced, and electrochemical coagulation processes for their removal under realistic water-quality conditions. Mechanistic sections describe how aluminum-, iron-, magnesium- and zirconium-based coagulants, including pre-polymerized and composite formulations (e.g., IPC-type coagulants, PSiFAC-Mg, ZrCl₄), remove fluoride via Al–F complexation, Al–F–OH co-precipitation, ion exchange, and sweep flocculation, while Cr(VI) control relies on Fe(II)-mediated reduction to Cr(III), followed by adsorption and co-precipitation with metal hydroxides. The review assesses how water chemistry and operating conditions affect single- and multi-contaminant removal, highlighting competition among fluoride, Cr(VI), nutrients, and other oxyanions. Performance data from bench-, pilot-, and selected full-scale studies show that optimized coagulation and electrocoagulation can substantially reduce fluoride and Cr(VI) (to drinking-water-relevant levels) in diverse urban waters, but also reveal persistent issues of sludge generation and stability, residual metals, process robustness, and cost. The review identifies priorities, including long-term urban-scale assessments, low-toxicity green coagulants, life-cycle and health impact assessments, and real-time coagulation control for fluoride and Cr(VI). Full article

Calcium–silicate–hydrate (C-S-H), the primary binding phase governing cement paste cohesion, undergoes progressive physicochemical transformation upon carbonation—a process that critically dictates concrete durability in atmospheric environments. When CO₂ penetrates the porous cement matrix, it triggers a cascade of degradation mechanisms: calcium leaching decalcifies the C-S-H structure, inducing polymerization of silicate chains from dimeric to longer-chain configurations, while concurrent precipitation of calcium carbonate and amorphous silica gel fundamentally reconstitutes the nanoscale architecture. These nanoscale alterations propagate to macroscopic property evolution, manifesting as initial strength and stiffness gains due to pore-filling carbonation products followed by eventual deterioration as the cohesive binding network deteriorates. This review synthesizes current understanding of carbonation-induced structural evolution, examining the coupled influences of environmental parameters—CO₂ concentration, relative humidity, and temperature—alongside C-S-H intrinsic chemistry (Ca/Si ratio, aluminum substitution, and alkali content) on reaction kinetics and material performance. However, significant knowledge gaps persist: predictive models for in-service carbonation rates remain elusive due to the disconnect between idealized laboratory conditions and the heterogeneous, cracked reality of field concrete; the causal linkage between nanoscale C-S-H alteration and macroscale cracking patterns along with physical performance is poorly resolved, and most mechanistic studies rely on synthetic C-S-H, neglecting the compositional complexity of real Portland cement systems. We further propose emerging protection strategies, including surface barrier coatings and low-carbon alternative binders (geopolymers, calcium sulfoaluminate cements, carbon-negative materials such as recycled cement), which demonstrate enhanced carbonation resistance. Future research priorities include developing effective coating barriers for carbonation protection, developing operando characterization techniques for real-time reaction monitoring, deploying machine learning algorithms to bridge atomistic simulations with structural-scale predictions, and establishing long-term field performance databases to validate laboratory-derived degradation models. Full article

Industrial wastewater containing heavy metals such as iron (Fe) and copper (Cu) remains a major environmental concern in Malaysia, since industrial effluents significantly contribute to national water pollution loads. Without proper treatment, these contaminants can accumulate in the ecosystem and pose long term risks to human health and aquatic life. This study evaluates the performance, sludge characteristics, and cost implications of alkaline precipitation using sodium hydroxide (NaOH) and calcium oxide (CaO) in the presence and absence of a polymeric flocculant (SW204) for heavy metal removal. Experimental findings reveal that both NaOH and CaO effectively removed heavy metals, where NaOH achieved removal efficiencies of 91.6% for Fe and 93.5% for Cu, while CaO removed 98.9% of Fe and 99.17% of Cu. The addition of polymer improved the treatment efficiency where removal up to 99.73% Fe and 99.80% Cu was achieved with the CaO and polymer system. Settling time improved drastically from 30 min when using NaOH to 2 min when using CaO and the polymer system, indicating the formation of denser and more compact flocs. The specific gravity and sludge weight also increased by approximately 4% with polymer addition, which may influence the disposal costs. Economic analysis revealed that CaO treatment is substantially more cost-effective than NaOH, yielding savings of approximately RM 15.77 per m⁻³ of effluent treated. Therefore, the combination of CaO and polymers provided the best balance of removal efficiency, settling performance, and cost reduction. The findings support the use of CaO-based systems as sustainable, high-efficiency alternatives for industrial wastewater treatment, all of which aligns with UN Sustainable Development Goals 6 (Clean Water and Sanitation) and 12 (Responsible Consumption and Production). Full article

To address the limited selectivity of conventional membrane materials toward sulfonamide antibiotics, this study employed a DFT calculation approach to optimize the design of a molecularly imprinted system for sulfadiazine (SDZ). A hierarchical set of template molecules—aniline (ANL), sulfanilamide (SNM), and SDZ—was introduced to systematically elucidate structure-dependent template–monomer matching mechanisms in sulfonamide imprinting systems. Through rational screening, trifluoroethyl methacrylate (TFEMAA) was identified as the optimal functional monomer, with an optimal imprinting molar ratio of 1:4 (SDZ to TFEMAA). Guided by the simulation results, SDZ molecularly imprinted polymers (MIPs) were synthesized via precipitation polymerization and systematically characterized for their morphology and recognition properties. The MIPs exhibited a well-defined spherical morphology with abundant imprinted cavities, achieving adsorption equilibrium within 1.5 h. The adsorption kinetics followed a pseudo-second-order model, indicating a chemisorption-dominated process. Scatchard analysis revealed the presence of both high- and low-affinity binding sites in the MIPs. Selectivity experiments, quantified by distribution coefficients (K_d) and selectivity coefficients (k), demonstrated a significantly higher adsorption capacity for SDZ than for structural analogs and non-analogs. In real water samples, the MIPs outperformed conventional HLB sorbents and showed strong anti-interference capability (RSD < 3%). This work provides a material foundation for developing highly selective SDZ-imprinted membranes and advances the application of molecular imprinting technology in membrane separation systems. Full article

Poor aqueous solubility remains a major limitation for the oral delivery of many active pharmaceutical ingredients (APIs). Deep eutectic solvents (DESs) exhibit remarkable drug-solubilization capacity, yet rapid precipitation upon aqueous dilution can compromise their ability to sustain supersaturation. This study investigates polymer-embedded DES (PEDES) systems as liquid supersaturating drug delivery platforms in which hydration and polymer chemistry jointly govern thermodynamic solubilization and kinetic stabilization. A choline chloride/DL-malic acid DES was prepared with 5% or 15% (w/w) water and combined with polyvinylpyrrolidone (PVP) or polyacrylic acid (PAA). Griseofulvin (GRF) was used as a precipitation-prone model drug. Structural characterization (ATR-FTIR, ¹H-NMR), equilibrium solubility measurements, storage stability studies, and non-sink dissolution testing were conducted to elucidate formulation behavior. The DES systems enhanced GRF solubility by up to ~59-fold relative to phosphate buffer (PBS, pH 6.8). Polymer incorporation produced hydration- and concentration-dependent effects. These results suggest the presence of competitive or cooperative interaction regimes. At 5% water, PEDES formulations failed to prevent recrystallization and showed limited supersaturation maintenance. In contrast, PEDES systems containing 15% water exhibited improved stability, with the formulation containing 4% PAA sustaining elevated drug concentrations for 120 min under non-sink conditions. Low-frequency solution-state ¹H-NMR confirmed stronger GRF–PAA interactions relative to PVP, supporting the role of polymer–drug association in supersaturation stabilization. These findings demonstrate that PEDES performance emerges from a hydration-dependent balance between solvent structuring and drug–polymer interactions, highlighting hydration and polymer functionality as key parameters for the rational design of liquid supersaturating systems. Full article

Coagulation significantly alters molecular characteristics and oxidizability of dissolved organic matters (DOM), while the linkage between DOM molecular characteristics and fragmentation pathways were unclear for the following processes. Here, four typical coagulation processes were employed to improve DOM molecular properties in leachate, and their subsequent impact on oxidizability in ozonation was identified. The results indicate that Polyaluminum chloride (PAC), Polyferric sulfate (PFS), Polyaluminium ferric chloride (PAFC) and Polymerized aluminum ferric silicate (PSAF) can all reduce the COD and TOC levels of the leachate concentrate through coagulation and precipitation, with PAC achieving the highest removal efficiency. PAC-ozonation effectively removes aromatic and unsaturated compounds, significantly improving DOM composition and enhancing conditions for subsequent oxidation. In contrast, PFS shows the poorest removal of aromatics (2.92%) and polycyclic aromatics (9.81%), along with the highest NOSC (−0.5036) and lowest (DBE-O)/C (−0.0051), indicating greater oxidation resistance. Only 11% of COD was further removed by ozonation after PFS treatment, suggesting limited reactivity of the residual DOM. Machine learning analysis of molecular transformation networks further confirmed that PFS treatment produced the fewest conversion pathways following ozonation. This indicates the choice rules and relationship between coagulation and ozonation for landfill leachate. This work provides an effective strategy to enhance leachate treatability and reduce energy and reagent consumption in subsequent processes, thereby contributing to more sustainable and cost-effective landfill leachate management. Full article

The synthesis of enantiomerically pure chiral β-nitroalcohols is a crucial objective in asymmetric catalysis. In order to efficiently obtain such chiral products, we developed a series of thermoresponsive, oxazoline–copper catalysts (Cu^II-PN_xFe_yO_z) via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. These catalysts can self-assemble in water into single-chain nanoparticles (SCNPs) with biomimetic behavior, in which intramolecular hydrophobic and metal-coordination interactions generate a confined hydrophobic cavity. Comprehensive characterization by FT-IR, TEM, DLS, CD, CA, and ICP analysis confirmed the nanostructure and composition. When applied to the aqueous-phase asymmetric Henry reaction between nitromethane and 4-nitrobenzaldehyde, the optimal catalyst (2.0 mol%) achieved a quantitative yield (96%) with excellent enantioselectivity (up to 99%) within 12 h. Furthermore, the thermosensitive poly(N-isopropylacrylamide, NIPAAm) block enabled facile catalyst recovery through temperature-induced precipitation above its lower critical solution temperature (LCST). This work presents an efficient and recyclable biomimetic catalytic system, offering a novel strategy for designing sustainable chiral catalysts for green organic synthesis. Full article

Ion chromatography (IC) serves as a pivotal technique in trace ion analysis, and the separation performance of IC is largely determined by the properties of stationary phases. In contrast to silica-based matrices, polymer-based stationary phases have garnered significant interest owing to their outstanding pH stability and mechanical robustness. However, unmodified polymer matrices usually lack necessary ion exchange functions and selectivity; therefore, precise functional modification is the key to improving their chromatographic separation performance. This paper provides a systematic overview of recent advances in the synthesis and functional modification of polymer-based anion exchange chromatography stationary phases over the past few years. Firstly, the types and characteristics of polymer matrices commonly used for functional modification are summarized; secondly, the origin and improvement of common synthesis methods such as microporous membrane emulsification, droplet microfluidics, suspension polymerization, emulsion polymerization, soap-free emulsion polymerization, precipitation polymerization, dispersion polymerization, and seed swelling are introduced according to the molding methods of polymer matrices; furthermore, the principles, characteristics, and development status of mainstream functionalization strategies, including chemical derivatization, surface grafting, latex agglomeration, and hyperbranching, are emphasized. Finally, the existing challenges and prospective development trends in this field are discussed and outlooked, with the purpose of offering insights for the targeted design and practical application of high-performance polymer-based anion exchange chromatography stationary phases. Full article

Ciprofloxacin, being a widely used antibiotic agent, has sparked growing interest in the field of molecularly imprinted polymers (MIP) for its selective recognition and removal. This review provides a comprehensive analysis of the recent advances in the synthesis and applications of ciprofloxacin-imprinted polymers. The examination of synthesis compositions for the preparation of these polymers includes thorough discussions on functional monomers, crosslinkers, initiators, and solid supports. Various imprinting techniques, including bulk, precipitation, co-precipitation, and surface polymerization, have been assessed for the fabrication of the imprinted polymers. Furthermore, the advancing imprinting techniques, encompassing nano-scale imprinting, multi-functional monomers, multi-template imprinting, and electrochemical imprinting, are also highlighted. Additionally, an extensive exploration of the diverse applications of these polymers is also presented. These applications encompass selective separation and removal of ciprofloxacin from environmental samples, visual and electrochemical detection in complex matrices, their use as a stationary phase for HPLC, drug release, and photocatalysis. This review offers valuable insights into the current advancements and potential future directions in the development of ciprofloxacin-imprinted polymers, emphasizing their importance in diverse analytical and environmental applications. Full article

Cemented tailings backfill (CTB) is widely used in mining operations due to its operational simplicity, reliable performance, and environmental benefits. However, the poor consolidation of fine tailings with ordinary Portland cement (OPC) remains a critical challenge, leading to excessive backfill costs. This study addresses the utilization of modified manganese slag (MMS) as a supplementary cementitious material (SCM) for fine tailings from an iron mine in Anhui, China. Sodium silicate (Na₂SiO₃) modification coupled with melt-water quenching was implemented to activate the pozzolanic reactivity of manganese slag (MS) through glassy structure alteration. The MMS underwent comprehensive characterization via physicochemical analysis, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) to elucidate its physicochemical attributes, mineralogical composition, and glassy phase architecture. The unconfined compressive strength (UCS) of the CTB samples prepared with MMS, OPC, tailings, and water (T-MMS) was systematically evaluated at curing ages of 7, 28, and 60 days. The results demonstrate that MMS predominantly consists of SiO₂, Al₂O₃, CaO, and MnO, exhibiting a high specific surface area and extensive vitrification. Na₂SiO₃ modification induced depolymerization of the highly polymerized Q⁴ network into less-polymerized Q² chain structures, thereby enhancing the pozzolanic reactivity of MMS. This structural depolymerization facilitated formation of stable gel products with low calcium–silicon ratios, conferring upon the T-MMS10 sample a 60-day strength of 3.85 MPa, representing a 94.4% enhancement over the T-OPC. Scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) analysis revealed that Na₂SiO₃ modification precipitated extensive calcium silicate hydrate (C-S-H) gel formation and pore refinement, forming a dense networked framework that superseded the porous microstructure of the control sample. Additionally, the elevated zeta potential for T-MMS10 engendered electrostatic repulsion, while the aluminosilicate gel provided imparted lubrication, collectively improving the flowability of the composite slurry exhibiting a 26.40 cm slump, which satisfies the requirements for pipeline transportation in backfill operations. Full article

Thermochromic smart windows are a promising technology to reduce energy consumption in buildings, particularly in tropical regions where cooling demands are high. Vanadium dioxide (VO₂) is the most studied thermochromic material due to its reversible semiconductor-to-metal transition near 68 °C. Conventional synthesis routes require long reaction times and post-annealing steps. In this work, we report a rapid hydrothermal synthesis of monoclinic VO₂(M) and tungsten-doped VO₂(M) powders obtained within only 6 h at 270 °C, using vanadyl sulfate as precursor and controlled precipitation at pH ≈ 8.5. Differential scanning calorimetry confirmed the reversible transition at 59 °C for the undoped VO₂, with a hysteresis of 18 °C, while tungsten doping reduced the transition temperature by ~17 °C per wt.% of W. X-ray diffraction verified the monoclinic phase with minor traces of VO₂(B), a non-thermochromic polymorph of VO₂, and microstructural analysis revealed crystallite sizes below 35 nm. Electron microscopy and dynamic light scattering confirmed particle sizes suitable for dispersion in polymeric matrices. This approach significantly reduces synthesis time compared to typical hydrothermal methods requiring 20–48 h and avoids further annealing. The resulting powders provide a low-cost and scalable route for fabricating thermochromic coatings with transition temperatures closer to ambient conditions, making them relevant for smart-window applications in tropical climates, where lower transition temperatures are generally regarded as beneficial. Full article

Urease-producing bacteria (UPB) have great potential for the bioremediation of heavy-metal pollution through biomineralization and adsorption. In this study, a strain of UPB, C7-12, was isolated from heavy-metal-contaminated soil in a lead–zinc mining area and identified as Serratia marcescens. The heavy-metal removal ability, influencing factors, and precipitation mode of this UPB strain in solution were investigated. The cadmium (Cd) removal rate in a Cd (1 mg/L) solution from C7-12 reached 85%, and pH was the main influencing factor. With urea mediation, S. marcescens C7-12 biomineralizes the Cd²⁺ in solution to form CdCO₃ and removes it through extracellular precipitation and surface adsorption. Furthermore, the removal rates of Cd²⁺, Pb²⁺, Zn²⁺ and Cu²⁺ in solution by S. marcescens C7-12 were 33–65%, 28–32%, 22–49%, and 38–44%, respectively. The precipitation mode involves coprecipitation of multiple heavy metals to form a mineral. These heavy metals are adsorbed on the surface of bacteria through the participation of carboxyl, amino, and phosphate functional groups and extracellular polymeric substances. Therefore, S. marcescens C7-12 has strong biomineralization and adsorption capacity for heavy-metal ions in solution, which can provide potential resources for the bioremediation of heavy-metal-contaminated soil and water. Full article