Search Results (634)

Brilliant blue, as a pigment food additive, has all the characteristics of printing and dyeing wastewater and belongs to persistent and refractory organic compounds. The photocatalysis–Fenton reaction system consists of two parts: photocatalytic reaction and Fenton reaction. Electrons promote the decomposition of H₂O₂ to produce •OH. In addition, the effective separation of e- and h⁺ by light strengthens the direct oxidation of h⁺, and h⁺ reacts directly with OH⁻ to produce •OH, which can further promote the removal of organic pollutants. In this paper, g-C₃N₄ and Fe/g-C₃N₄ photocatalysts were prepared by the thermal polycondensation method. Fe/g-C₃N₄ of 15 wt% can reach 98.59% under the best degradation environment, and the degradation rate of g-C₃N₄ is only 7.6% under the same conditions. The photocatalytic activity of the catalysts was further studied. Through active species capture experiments, it is known that •OH and •O₂⁻ are the main active species in the system, and the action intensity of •OH is greater than that of •O₂⁻. The degradation reaction mechanism is that H₂O₂ combines with Fe²⁺ in Fe/g-C₃N₄ to generate a large amount of •OH and Fe³⁺, and the combination of Fe-N bonds accelerates the cycle of Fe³⁺/Fe²⁺ and promotes the formation of •OH, thereby accelerating the degradation of target pollutants. •O₂⁻ can reduce Fe³⁺ to Fe²⁺, Fe²⁺ reacts with H₂O₂ to produce •OH, which promotes degradation, and •O₂⁻ itself also plays a role in degradation. In addition, under the optimal experimental conditions obtained by response surface experiments, the fitting degree of first-order reaction kinetics is 0.96642, and the fitting degree of second-order reaction kinetics is 0.57884. Therefore, this reaction is more in line with first-order reaction kinetics. The adsorption rate is only proportional to the concentration of Fe/g-C₃N₄. Full article

2-methylisoborneol (MIB, d = 0.6 nm) and dimethyl disulfide (DMDS, d = 0.7 nm) produced by algal metabolism are the main olfactory contaminants of drinking water. Activated carbon (AC) adsorption is an effective method to remove MIB/DMDS, yet critical gaps remain regarding the dominant factors and mechanisms governing their different adsorption performance. The microporous filling mechanism is the dominant mechanism for the adsorption of MIB and DMDS by AC. Surface functional groups play a supporting role in the adsorption process by modulating the hydrophilicity/hydrophobicity of the carbon surface. This study systematically evaluated the adsorption performance of three ACs—coconut shell-derived (CSC), coal-based (CAC), and Sargassum-derived (SAC)—for MIB and DMDS removal. Comparative analysis revealed the superior adsorption performance of CSC, achieving 87.41% removal of MIB and 71.2% removal of DMDS at 20 mg/L. Both MIB and DMDS adsorption adhere to the Langmuir isotherm, indicating monolayer coverage with uniform energy. Kinetic studies demonstrated that the PSO model fits the MIB adsorption process best, while the PFO model fits the DMDS adsorption process best. The FTIR confirmed physical adsorption, with no new chemical bonds formed. Furthermore, regenerated CSC retains significant adsorption capacities, achieving 85.89% and 68.49% of the original capacity for MIB and DMDS, respectively, after five regeneration cycles. This research provides fundamental insights into the mechanistic role of AC properties in odorant removal processes, supporting its sustainable application in water treatment. Full article

Acetaminophen (APAP) is a widely used pharmaceutical increasingly detected as a contaminant in aquatic environments due to its persistent nature and incomplete removal by conventional wastewater treatment. This study investigates the adsorption performance and mechanisms of commercial activated carbon (M) and its hydrothermally modified form (MH) for APAP removal. Characterization via elemental analysis, X-ray photoelectron spectroscopy (XPS), and N₂ adsorption isotherms revealed that hydrothermal treatment reduced oxygen content and enhanced micro- and mesopore volumes, resulting in a more homogeneous and carbon-rich surface. Batch adsorption experiments conducted under varying pH (5–7) and temperature (30–40 °C) conditions showed that MH achieved up to 94.3% APAP removal, outperforming the untreated carbon by more than 15%. Kinetic modeling indicated that adsorption followed a pseudo-second-order mechanism (R² > 0.99), and isotherm data fitted best to the Langmuir model for MH and the Freundlich model for M, reflecting their differing surface properties. Adsorption was enhanced at lower pH and higher temperatures, consistent with an endothermic and pH-dependent mechanism. Complementary density functional theory (DFT) simulations confirmed that π–π stacking is the dominant interaction between APAP and the carbon surface. The most favorable configuration involved coplanar stacking with non-oxidized graphene (ΔG = −33 kJ/mol), while oxidized graphene models exhibited weaker interactions. Natural Bond Orbital (NBO) analysis further supported the prevalence of π–π interactions over dipole interactions. These findings suggest that surface deoxygenation and improved pore architecture achieved via hydrothermal treatment significantly enhance APAP adsorption, offering a scalable strategy for pharmaceutical pollutant removal in water treatment applications. Full article

The Ti6Al4V alloy is considered the most beneficial of the titanium alloys for use in biomedical applications. However, it corrodes when exposed to various biocompatible fluids. This investigation aims to evaluate the corrosion inhibition performance of the Ti6Al4V in a saline solution (SS) using thiocolchicoside (TCC) drug as an environmentally acceptable corrosion inhibitor. The corrosion assessments were conducted using potentiodynamic polarization curves (PPCs), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) methodologies, supplemented by scanning electron microscopy (SEM), energy-dispersive X-ray (EDS) analysis, atomic force microscopy (AFM), and contact angle (CA) measurements. The outcomes indicated that the inhibitory efficacy improved with higher TCC concentrations (achieving 92.40% at 200 mg/L of TCC) and diminished with an increase in solution temperature. TCC’s physical adsorption onto the surface of the Ti6A14V, which adheres to the Langmuir adsorption isotherm, explains its mitigating power. The TCC acts as a mixed-type inhibitor. The adsorption and inhibitory impact of TCC were examined at various temperatures using PPC and EIS. When TCC is present, the corrosion’s apparent activation energy is higher (35.79 kJ mol⁻¹) than when it is absent (14.46 kJ mol⁻¹). In addition, the correlation between the structural properties of thiocolchicoside (TCC) and its corrosion inhibition performance was systematically analyzed. Density Functional Theory (DFT) calculations were utilized to characterize the adsorption mechanism, supported by Natural Bond Orbital (NBO) analysis and Molecular Dynamics (MD) simulations. The combined computational and electrochemical findings confirm that TCC provides effective and enhanced corrosion protection for the Ti6Al4V alloy in a saline environment. These characteristics provide compelling evidence for the suitability of these pharmaceutical compounds as promising corrosion inhibitors. Full article

A theoretical study of the adsorption of lithium–sulfur molecules (Li₂S and Li₂S₂) on graphene with three and four vacancies was conducted. The study analyzed the stability, adsorption geometry, electronic structure, charge distribution, and forming bonds between the molecule and the substrates. It has been demonstrated that both types of defects result in stable adsorptions; however, the underlying mechanisms differ. The three-vacancy graphene exhibits a site that favors the adsorption through bonds between S atoms and the substrate, while the graphene with four vacancies promotes the anchoring of molecules through Li atoms. The mechanism associated with the three-vacancy graphene results in increased exothermic adsorption energies. Full article

Organophosphate pesticides are among the most persistent and toxic contaminants in aquatic environments, requiring effective strategies for detection and remediation. In this work, density functional theory (DFT) calculations were employed to investigate the adsorption of nine representative organophosphates (glyphosate, malathion, diazinon, azinphos-methyl, fenitrothion, parathion-methyl, disulfoton, tokuthion, and ethoprophos) on mercaptobenzothiazole disulfide (MBTS) and MBTS-functionalized graphene (G–MBTS). All simulations were performed in aqueous solution using the SMD solvation model with dispersion corrections and counterpoise correction for basis set superposition error. MBTS alone displayed a range of affinities, suggesting potential selectivity across the organophosphates, with adsorption energies ranging from 0.27 to 1.05 eV, malathion being the strongest binder and glyphosate the weakest. Anchoring of MBTS to graphene was found to be highly favorable (1.26 eV), but the key advantage is producing stable adsorption platforms that promote planar orientations and $\pi$–$\pi$/dispersive interactions. But the key advantage is not stronger binding but the tuning of interfacial electronic properties: all G–MBTS–OP complexes show uniform, narrow HOMO-LUMO gaps (∼0.79 eV) and systematically larger charge redistribution. These features are expected to enhance electrochemical readout even when adsorption strength was comparable or slightly lower (0.47–0.88 eV) relative to MBTS alone. A Quantum Theory of Atoms in Molecules (QTAIM) analysis of the G–MBTS–malathion complex revealed a dual stabilization mechanism: multiple weak C–H⋯$\pi$ interactions with graphene combined with stronger S⋯O and hydrogen-bonding interactions with MBTS. These results advance the molecular-level understanding of pesticide–surface interactions and highlight MBTS-functionalized graphene as a promising platform for the selective detection of organophosphates in water. Full article

Formaldehyde is a toxic gas commonly found in industrial emissions, and ZnO is widely used for its detection due to its excellent gas-sensing properties. Most studies focus on non-polar or low-index ZnO surfaces, whereas investigations on high-index polar surfaces remain limited. In this work, density functional theory (DFT) was employed to study CH₂O adsorption on the ZnO [$10\overline{11}$] surface. By exploring various coverages, adsorption sites, and unit cell dimensions, ten stable configurations were identified. A maximum adsorption energy of −2.19 eV/CH₂O on configuration S1 was obtained, surpassing reported low-index surfaces. Strong adsorption originated from dual unsaturated Zn bonds, which promoted C–C formation between CH₂O molecules and induced synergistic Zn–O bonding. Adsorption further led to sp³-like hybridization and O 2p/Zn 3d orbital interactions, significantly narrowing the band gap. Electron redistribution, as evidenced by charge density analysis, revealed strong electronic modulation. This work clarifies the microscopic mechanism of ZnO high-index surfaces, offering insights for optimizing gas-sensing materials. Full article

With the expansion of industrial production capacity, a substantial volume of hazardous wastewater containing Pb (II) and Ni (II) requires treatment. Kaolin, a low-cost adsorbent with strong adsorption properties, was modified through thermal activation at 750 °C, 850 °C, and 950 °C to enhance its adsorption capacity. Following the optimization of pH, reaction time, temperature, heavy metal concentrations, and adsorbent amount, the 850-K was found to have the best removal efficiency, achieving removal rates > 90% for both PbCl₂ and NiCl₂, and the removal efficiency of PbCl₂ was higher compared to NiCl₂. The pseudo-second-order kinetics and Langmuir model could reasonably match the adsorption processes of PbCl₂/NiCl₂. The experimental findings were corroborated through simulations of adsorption distance, variations in bond length/bond angle, adsorption energy, frontier molecular orbital, charge density, and differential charge density. The differences in reactions between adsorbents and PbCl₂/NiCl₂ were primarily due to the electron transfer direction and bonding mechanisms. The O atoms were the main reactive atoms of the adsorbents, capable of forming covalent bonds with both PbCl₂ and NiCl₂, and the Cl atoms could form either ionic or covalent bonds with the adsorbent. Pb could form covalent bonds with the adsorbent, while Ni might be adsorbed through electrostatic interactions. Full article

In response to the issues of increased brittleness and insufficient toughness in microbially solidified saline sandy soils in cold and arid plateau regions, this study investigated saline sandy soils and indigenous microorganisms from the Qaidam Basin, Qinghai. A dual-reinforcement method combining microbial-induced calcium carbonate precipitation (MICP) with alkali-modified reed fiber (ARF) was proposed to enhance both strength and ductility. The study explored the adsorption characteristics and solidification mechanisms of this approach. Key innovations include: (1) alkali modification significantly improved the interfacial bonding between reed fibers and sand particles, with pull-out tests indicating a 1.24-fold increase in adhesion strength; (2) an orthogonal experimental design identified optimal parameters—fiber length of 15 mm, fiber content of 0.5%, and cementation solution concentration of 3 mol/L—leading to the development of a synergistic “microbial cementation–fiber bridging” enhancement model. Experimental results showed that the proposed method increased the unconfined compressive strength (UCS) of the solidified soil to 2082.85 kPa, 2.99 times higher than that of traditional MICP-treated soil, while it significantly enhanced the ductility of the soil. This approach offers a mechanically robust and environmentally adaptive solution within the ambient temperature range of 0–35 °C for the ecological restoration of saline soils in high-altitude regions. Full article

Generally, atomic doping is an effective method to address the weak bonding strength of the graphene/aluminum (Gr/Al) composite interface structure caused by physical adsorption, thereby enhancing the mechanical properties of the interface structure. In this paper, the nanoscopic influence mechanisms of atomic (M, including 12 types of atoms (elements)) doping in the aluminum matrix (Al) on the ideal strength of the Gr/Al interface structures are investigated based on density functional theory. The analysis of the electronic properties of the typical interface structures reveals that doping with scandium (Sc), copper (Cu) and manganese (Mn) atoms can all improve the interface binding energy of the Gr/Al structures, but their effects on the ideal strength are different. Sc doping disrupts the symmetry of the graphene structure so as to enhance the interface binding energy, but the ideal strength of the Gr/Al structures is decreased. For Cu doping it shows good compatibility with the Al matrix and the interface binding energy is enhanced through Cu alloying with the Al matrix, while the ideal strength of the interface remains basically unchanged. As for Mn doping, it causes the charge to accumulate around the Mn atoms and a resonance peak between the d_Z² orbitals of Mn and the p_x orbitals of Al to form, thereby improving the ideal strength of the interface structure. This study provides valuable insights for the design of Gr/Al composites by elucidating the underlying mechanisms for enhancing interface mechanical properties. Full article

Plastics are essential in modern life but accumulate as waste. Mechanical reprocessing reduces material quality, whereas thermochemical routes require harsh conditions and are costly to upgrade. Together, these factors hinder the large-scale recovery of plastics into equivalent materials. Metal–organic frameworks provide a programmable platform where reticular design fixes porosity and positions well-defined Lewis, Brønsted, redox, and photoredox sites that can preconcentrate oligomers and align scissile bonds for activation. These attributes enable complementary pathways spanning hydrolysis, alcoholysis, aminolysis, photo-oxidation, electrocatalysis, and MOF-derived transformations, with adsorption-guided capture-to-catalysis workflows emerging as integrative schemes. In this review, we establish common figures of merit such as space–time yield, monomer selectivity and purity, energy intensity, site-normalized turnover, and solvent or corrosion footprints. These metrics are connected to design rules that involve active-site chemistry and transport through semi-crystalline substrates. We also emphasize durability under hot aqueous, alcoholic, or oxidative conditions as essential for producing polymer-grade products. Full article

A novel magnetic composite, Fe₃O₄@MIL-53(Fe Cu), was successfully synthesized and applied for the efficient removal of methyl orange (MO) from aqueous solutions. The ad sorption performance was systematically evaluated under various conditions, including adsorbent dosage, solution pH, coexisting anions, and regeneration cycles. The results demonstrated that an optimal dosage of 20 mg achieved a removal efficiency exceeding 85%, with maximum adsorption observed at pH 3. The presence of common anions (Cl⁻, SO₄²⁻, CO₃²⁻, and PO₄³⁻) showed negligible effects on MO removal. Kinetic studies revealed that the adsorption process followed the pseudo-second-order model. Although minor chemisorption contributions were observed, the Dubinin–Radushkevich (D–R) model confirmed the predominance of physical adsorption. The Freundlich isotherm provided the best fit to the equilibrium data, indicating a maximum adsorption capacity of 193.65 mg/g and suggesting multilayer adsorption on a heterogeneous surface. Thermodynamic analysis confirmed the spontaneous and endothermic nature of the adsorption process. The primary mechanisms governing MO adsorption were identified as electrostatic attraction, π–π interactions, and hydrogen bonding. The composite exhibited excellent reusability over multiple cycles, demonstrating its potential for practical wastewater treatment applications. Full article

The deposition of asphaltenes poses a critical challenge to the petroleum industry, reducing the efficiency of oil wells and, in severe cases, clogging pipelines. Dispersants are widely used to enhance asphaltene stability, but asphaltenes are complex, solubility-defined compounds with variable properties, leading to uncertainties in dispersant microscopic mechanisms, macroscopic effects, and their relationships—requiring further study. This work investigated two anionic dispersants (sodium dodecyl benzene sulfonate (SDBS) and dodecyl benzene sulfonic acid (DBSA)) for dispersing GT asphaltene (GT-ASP, isolated from offshore heavy oil), aiming to improve offshore heavy oil stability. Using an asphaltene–toluene system, it analyzed dispersant effects on GT-ASP stability, particle size, and adsorption and underlying mechanisms. DBSA showed superior performance: at 1000 ppm (w/v), it reduced GT-ASP average particle size from ~160 nm to ~29 nm and increased the onset of the flocculation point (OFP) from 33.5 vol% to 63.0 vol%, driven by chemical adsorption, hydrogen bonding, and π–π conjugation. In contrast, SDBS promoted aggregation: particle size reached 257 nm (1000 ppm (w/v)) and 1271 nm (5000 ppm (w/v)), with OFP at 54.6 vol%, likely due to Na⁺-induced charge neutralization, insufficient steric hindrance, and “micellar bridges” via SDBS self-aggregation. Finally, this study makes a valuable contribution to both the theoretical guidance and the practical application of asphaltene dispersants. Full article

Nitrogen (N) and phosphorus (P) play vital roles in crop growth. However, conventional fertilizers exhibit low utilization efficiency, making them prone to causing resource wastage and water eutrophication. Although metal–organic frameworks (MOFs) have shown great potential for application in controlled-release fertilizers (CRFs), currently reported MOF-based CRFs suffer from low nutrient content, which limits their further application. To address this issue, this study synthesized a series of hierarchically porous MOFs, denoted as MIL-156(X), using sodium acetate as a modulator under hydrothermal conditions. These materials were subsequently loaded with urea and phosphate from aqueous solution to form MOFs-based CRFs (N-P-MIL-156(X)). Results indicate that MIL-156(X) retain microporous integrity while incorporating abundant mesopores. Increasing modulator content reduced particle size and average pore diameter but increased specific surface area and adsorption capacity for urea and phosphate. MIL-156-H (with a high modulator content addition) exhibited the highest adsorption capacity, conforming to Langmuir isotherm and pseudo-second-order kinetics. The adsorption mechanisms of urea and phosphate involved hydrogen bonding and the formation of Ca intra-spherical complexes, respectively. N-P-MIL-156-H contained 10.8% N and 16.3% P₂O₅, with sustained release durations exceeding 42 days (N) and 56 days (P₂O₅) in an aqueous solution. Pot trials demonstrated significantly higher nutrient use efficiency (N-44.8%, P₂O₅-16.56%) and a 12.22% yield increase compared to conventional fertilization (N-35.6%, P₂O₅-13.32%). Thus, N-P-MIL-156-H-based fertilization significantly promotes rice growth and N/P utilization efficiency, offering a promising strategy for developing controlled-release fertilizers and improving nutrient management. Full article

In response to the actual needs of pure copper bonding wires, it is crucial to develop a chromium-free passivator that is environmentally friendly and has excellent corrosion resistance. In this study, three different composite organic formulations of chromium-free passivation solutions are selected: 2-Amino-5-mercapto-1,3,4 thiadiazole (AMT) + 1-phenyl-5-mercapto tetrazolium (PMTA), 2-mercaptobenzimidazole (MBI) + PMTA, and Hexadecanethiol (CHS) + sodium dodecyl sulfate (SDS). The performance analysis and corrosion mechanism were compared with traditional hexavalent chromium passivation through characterization techniques such as XRD, SEM, and XPS. The results show that the best corrosion resistance formula is the combination of the PMTA and MBI passivation agent, and all its performances are superior to those of hexavalent chromium. The samples treated with this passivation agent corrode within 18 s in the nitric acid drop test, which is better than the 16 s for Cr⁶⁺ passivation. The samples do not change color after being immersed in salt water for 48 h. Electrochemical tests and high-temperature oxidation test also indicate better corrosion resistance than Cr⁶⁺ passivation. Through the analysis of functional groups and bonding, the excellent passivation effect is demonstrated to be achieved by the synergistic action of the chemical adsorption film formation of PMTA and the anchoring effect of MBI. Eventually, a dense Cu-PMTA-BMI film is formed on the surface, which effectively blocks the erosion of the corrosive medium and significantly improves the corrosion resistance. Full article