Langmuir最新文献

Quaternary ammonium-graphite intercalation compounds (QA⁺-GICs) are promising negative electrode materials in dual-carbon batteries by virtue of safety, low cost, and environmental friendliness. However, the intercalation behavior of QA⁺ into graphite electrodes in mixed solvents has never been reported. Herein, spiro-(1,1')-bipyrrolidinium tetrafluoroborate dissolved in a dimethyl/propylene carbonate (DMC/PC) binary solvent system was employed in graphite/activated carbon (AC) capacitors. The storage behavior of the spiro-(1,1')-bipyrrolidinium cation into graphite is very related to the solvent composition of the electrolyte solutions. In situ X-ray diffraction tests revealed that the graphite electrodes can form different QA⁺-GICs during cycling, which is a key factor influencing the electrochemical performance of graphite/AC capacitors. Besides, the reversible thickness change of graphite in graphite/AC capacitors with different electrolytes during the charge-discharge process was also addressed. These findings provide sound evidence for the co-intercalation of the solvent with the cation.

Acid mine drainage (AMD) sludge is waste generated in the process of acid mine wastewater treatment, and the use of AMD sludge to prepare Fe₃O₄ to activate H₂O₂ degradation pollutants is an effective means of resource utilization. In this study, the heterogeneous catalyst Fe₃O₄-based composites were synthesized by a one-step method using AMD sludge as a raw material, and the Fe₃O₄-based materials before and after catalysis were characterized by powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of several key factors (pH values, H₂O₂ content, TC concentration, and Fe₃O₄ content) of tetracycline (TC) degradation were evaluated. The results revealed that the TC removal rate reached up to 95% within 120 min under optimal conditions (pH 3; H₂O₂, 5 mmol/L; TC concentration, 25 mg/L; Fe₃O₄ content, 1g/L). Moreover, ^•OH and ^•O₂^- radicals were generated during the Fenton-like degradation process, and the plausible degradation mechanism was discussed. Besides, the Fe₃O₄ catalyst exhibited fantastic stability after five cycles. In conclusion, this study is expected to promote the resource utilization of industrial sludge and provide a new material for the treatment of antibiotic-contaminated wastewater.

The home and personal care industry is evolving toward more sustainable and environmentally friendly ingredients. Rinse-off personal care products rely on formation of polymer-surfactant complexes to drive deposition of benefit agents (e.g., conditioning oils, fragrances, etc.) onto the skin or hair. The most used natural polymers for this purpose are cationic guar (catGuar) and cationic hydroxyethyl cellulose (catHEC), and the complexation of these polymers with surfactants has been rigorously characterized. Various gaps still exist with these polymers, specifically low biodegradation and undesirable aquatic toxicity profiles. Modified dextran offers an exciting solution as a biodegradable polysaccharide with a high natural origin content. This paper aims to compare the morphology of polymer-surfactant complexes formed between a cationic dextran (catDex) polymer with mixtures of sodium lauryl ether sulfate (SLES) and cocamidopropyl betaine (CapB) to the morphologies of complexes formed between catGuar or catHEC and the same surfactants. Solutions were designed to mimic industrially relevant shampoos. Through a suite of complementary techniques, unique nanometric sized complexes were observed to form between catDex-SLES/CapB compared to the widely reported micrometer-sized coacervates (liquid-liquid phase separation) or precipitates (liquid-solid) formed in catHEC or catGuar-SLES systems. Using a quartz crystal microbalance with dissipation, the adsorption behavior of the catDex-SLES/CapB is characterized on a silica-coated sensor. The results show deposition throughout the dilution regime for catDex-SLES/CapB where the highest deposition is recorded with the undiluted rinsing formulation. This contrasts with catHEC-SLES/CapB and catGuar-SLES/CapB where the highest deposition is recorded in phase-separated regimes. This result was extended to performance testing on hair, confirming that the unique complexes formed by catDex can drive remarkably high levels of silicone deposition from rinse-off personal care products. This innovative approach of utilizing catDex-SLES/CapB complexes could enable design of more sustainable formulations that rely on polycation-surfactant nanocarriers.

A coal tar pitch-based porous carbon adsorbent (CPA) was synthesized through a straightforward method involving the heating of a mixture of KOH and coal tar pitch (CTP). This CPA exhibited a high surface area of 1811.2 m² g^-1 and a large pore volume of 0.94 cm³ g^-1 when prepared with a CTP to KOH mass ratio of 1:4 at 800 °C. Parameters such as the heating temperature and activator dose were optimized to enhance the adsorption efficiency. The prepared CPA was extensively characterized by SEM, XRD, FTIR, and BET measurements. Notably, CPA presented a distinct adsorption performance for Orange G (OG), achieving a maximum adsorption capability of 449.7 mg g^-1. Kinetic studies indicated that the adsorption process followed the pseudo-second-order model, while the adsorption isotherm data demonstrated that both chemical and physical interactions favored OG adsorption. Thermodynamic analysis revealed that the adsorption of OG on CPA was spontaneous and exothermic and increased the entropy. Density functional theory (DFT) calculations provided insights into the adsorption mechanism, highlighting electrostatic interactions, hydrogen bonds, and π-π interactions as the dominant processes governing OG adsorption onto the adsorbent.

Recently, due to the promising application of metal oxide semiconductors in high-performance methane (CH₄) sensors, more attention has been paid to the development of feasible strategies for improving CH₄ sensing performance. Herein, we present a strategy of cadmium (Cd) doping to improve the CH₄ sensing property of In₂O₃ porous hollow nanospheres (PHNSs). The Cd-doped In₂O₃ PHNSs were prepared via an impregnation-calcination approach with self-made carbon nanospheres as a hard template. The samples were characterized by various techniques to evaluate their structure, morphology, surface state, composition, and band gap. When applied as a sensitive material in the CH₄ sensor, the Cd-doped In₂O₃ PHNSs, compared with bare In₂O₃ PHNSs, showed some significant improvements in performance, especially a reduced operating temperature (200 °C vs 300 °C), an enhanced response (9.5 vs 2.5 for 500 ppm of CH₄), a faster response speed (16 s vs 276 s), and better selectivity. In addition, the Cd-doped In₂O₃ sensor can also maintain a commendable long-term stability, and the range of its response amplitude within 30 days is only 6.3%. The sensitization effects of the Cd dopant on the In₂O₃ PHNSs are discussed.