The subimplantation model for hydrogenated amorphous carbon films deposited in electron cyclotron resonance plasma

The subimplantation model was used to explain the formation of a-C : H films deposited from a dual ECR-RF discharge of methane–argon (5%) mixture at low pressure. Combined optical transmission measurements, elastic recoil detection analysis, Raman spectra and residual stress measurements are used to fully characterise the films as deposited. The residual stress vs. bias plot shows a behavior similar to those already obtained for tetrahedral amorphous carbon (ta-C) and tetrahedral hydrogenated amorphous carbon (ta-C : H) films. In this study, the ions sticking the film surface are not monoenergetic, the stress data matches the theoretical model proposed by Davis. The optimum energy obtained is similar to that obtained for tetrahedral films.     

Pt–Cu Interaction Induced Construction of Single Pt Sites for Synchronous Electron Capture and Transfer in Photocatalysis

Single-atom photocatalysts have shown their fascinating strengths in enhancing charge transfer dynamics; however, rationally designing coordination sites by metal doping to stabilize isolated atoms is still challenging. Here, a one-unit-cell ZnIn₂S₄ (ZIS) nanosheet with abundant Cu dopants serving as the suitable support to achieve a single atom Pt catalyst (Pt₁/Cu–ZIS) is reported, and hence the metal single atom–metal dopant interaction at an atomic level is disclosed. Experimental results and density functional theory calculations highlight the unique stabilizing effect (Pt–Cu interaction) of single Pt atoms in Cu-doped ZIS, while apparent Pt clusters are observed in pristine ZIS. Specifically, Pt–Cu interaction provides an extra coordination site except three S sites on the surface, which induces a higher diffusion barrier and makes the single atom more stable on the surface. Apart from stabilizing Pt single atoms, Pt–Cu interaction also serves as the efficient channel to transfer electrons from Cu trap states to Pt active sites, thereby enhancing the charge separation and transfer efficiency. Remarkably, the Pt₁/Cu–ZIS exhibits a superb activity, giving a photocatalytic hydrogen evolution rate of 5.02 mmol g⁻¹ h⁻¹, nearly 49 times higher than that of pristine ZIS.     

Hydrothermal and Pyrolytic Conversion of Biomasses into Catalysts for Advanced Oxidation Treatments

Biomasses are very important natural products. Transferring biomass into catalysts for the advanced oxidation process (AOP) via heat treatment has attracted extensive attention. This review systematically introduces and summarizes two kinds of innovative biomass-based catalysts according to the treating temperature. At low temperature ( < 300  ° C), biomasses are converted into hydrothermal carbonation carbon (HTCC) with semiconductive properties for photocatalysis application. At high temperature ( > 300  ° C), by contrast, the products lose their semiconductive nature and become a conductive carbon-based conductor (biochar). They usually work as AOP catalysts by activating oxidant of O₂, H₂O₂, and peroxysulfate for environmental treatment. This review summarizes and compares HTCC and biochar according to their formation process, structure, catalytic mechanism, and key points for the activity enhancement. The active units in HTCC are the sp²-hybridized polyfuran unit while those in biochar are the persistent free radicals, nitrogen-containing unit, or defects. HTCC converts water into OH radicals by using the photoexcited electron/hole pairs induced by solar illumination, while biochar activates oxidants via the active unit on its surface. More importantly, this review summarizes and demonstrates the key points to obtain high-efficiency HTCC and biochar catalysts. Finally, conclusions are drawn and the future aspects for biomass-based catalysis are given.     

Adsorption behavior of Sb(III) in single and binary Sb(III)—Fe(II) systems on cationic ion exchange resin: Adsorption equilibrium,kinetic and thermodynamic aspects

The present study dealt with the mechanism of competitive adsorption of Sb(III) and Fe(II) ions from a copper-containing aqueous solution on Purolite S957, a commercially available cationic ion-exchange adsorbent. Experiments were conducted using aqueous copper sulfate solutions containing either single or conjoint ions, using both sedentary and batch adsorption techniques to ascertain the sensitivity of the adsorption process to variation in pH, mass of resin, contact time, and temperature as well as establishing the optimal range of variables for maximum ion removal. The data from single ion adsorption tests were fitted by non-linear regression techniques to Henry, Langmuir, Freundlich, Temkin, and Dubinin—Radushkevich isotherm models. Freundlich isotherm for Sb(III) and Freundlich and Henry models for Fe(II) solutions best express the adsorption equilibrium data; while for binary ion electrolytes, the extended Freundlich model fitted the data satisfactorily. The kinetic model adequately describing adsorption was shown to be the pseudo-first-order, underscoring the dominant role of physical adsorption playing in the process. Thermodynamic parameters for the adsorption process reveal differences in the Sb(III) adsorption mechanism from single ion and Sb(III)—Fe(II) containing electrolytes. The adsorption of Sb(III) alone is endothermic, whereas the process becomes exothermic in the Sb(III)—Fe(II) system.     

纳米铁系双金属复合材料还原水中硝酸盐氮

利用液相还原法分别制备了纳米Fe0、纳米Fe/Ni及Fe/Cu粒子,并在无氧条件下将其应用于水中硝酸盐污染物的去除研究,分别考察了负载量、硝酸盐初始浓度等条件对硝酸盐去除速率的影响,并对三种纳米材料还原硝酸盐的产物及反应机理进行了分析和讨论。实验结果表明,铜负载量为5.0%的纳米Fe/Cu粒子(投加量为1.5 g/L)在20 min内对硝酸盐的去除率接近100%,反应过程中有大量亚硝酸盐产生,但随着反应的进行又逐渐消失,反应的最终产物主要为氨氮,占体系总氮的75%,另有25%的氮损失;在纳米Fe0与Fe/Ni粒子还原硝酸盐产物中,氨氮的转化率均为95%以上。纳米Fe/Cu粒子对产物的选择性优于Fe0和Fe/Ni粒子。     

沸石咪唑酯骨架材料合成及其在气体吸附分离领域的研究进展

气体分离在石油化工和化工生产中有非常重要的作用。沸石咪唑酯骨架（ZIFs）作为一种新型的多孔材料，具有大比表面积、高孔隙率、多样的结构组成和超高的热稳定及化学稳定性，成为该领域的研究热点。本文围绕ZIFs材料的合成展开，详尽地总结了现阶段ZIFs在气体吸附分离领域的应用，重点介绍ZIFs在工业CO₂捕获及分离、轻质烃分离、气相色谱分离、用于气体分离的ZIFs基膜、惰性气体分离和有毒气体分离等行业的研究进展。同时指出，ZIFs材料在气体吸附分离领域的应用仍需要进一步研究，如新型低成本配体的开发、探索更多的合成方法来调整晶体结构、提升ZIFs材料的吸附效率，才能使ZIFs从实验室走向工业化。     

Microscopic single particle characterization of zeolites synthesized in a soil polluted by copper or cadmium and treated with coal fly ash

In the perspective of the development of new soil remediation technologies, zeolites can be directly synthesized in soil from fused coal fly ash to reduce heavy metal mobility and availability. Such a process promotes the formation of metal hydroxide/oxide precipitates which can be also occluded inside the structure of the forming minerals. In this study, different types of zeolites (zeolite X, P, and A) were synthesized by treating soil samples, artificially contaminated by high concentrations of Cu or Cd ions, with fused coal fly ash at 30 and 60 °C. The formed zeolites were characterized for their amount, structure, chemical composition and size. To accomplish this survey, besides quantitative X-ray diffraction analyses (XRD), an automated single particle analysis (ASPA) method using electron probe X-ray microanalysis (EPXMA) was employed for the first time for direct zeolite characterization in soil samples. The obtained results provide new information for assessing the role of heavy metals in zeolite crystallization in coal fly ash-treated soils. Heavy metal contamination, while not significantly hindering the zeolite formation process, can influence crystal size and preferentially drive zeolite synthesis toward the formation of sodalite unit-based zeolite X and zeolite A, even at 60 °C. The presence and nature of metal precipitate occlusions inside the forming zeolite minerals might have also favored the preferential synthesis of certain zeolitic structures.     

Rapid screening and quantification of cyromazine,melamine, ammelide,ammeline, cyanuric acid,and dicyandiamide in infant formula by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and triple quadrupole mass spectrometry

In the past few years, special concern for triazine pesticide cyromazine (CYRO) and its metabolites melamine (MM), ammelide (AMD), ammeline (AMN), cyanuric acid (CA), and dicyandiamide (DCD) residues has arisen in the food safety field on infant foods. In this work, screening and confirmation for infant milk powder samples were performed by quadrupole time-of-flight mass spectrometry (QTOF-MS). An accurate mass database was established. The matrix-matched internal standard calibration curves of UPLC–MS/MS were linear, with correlation coefficient (r²) higher than 0.994. The limits of quantification (LOQ) were 1.6, 5.0, 16.5, 10.0, 66.4, and 66.4 μg/kg for CYRO, MM, AMD, AMN, CA, and DCD, respectively. The average recoveries ranged from 64.8 to 103%. The retention time, intra- and inter-day precisions (relative standard deviation, RSDs) of 6 analytes were in the range of 0.02–0.05%, 2.4–6.1%, and 7.2–11.2%, respectively. CYRO and MM residues in some infant milk powder samples were confirmed. Quantitation of positive samples was performed using the internal standard method and six-point matrix-matched calibration curves. The content for CYRO in all 8 samples and MM in 4 samples were in the range of 3.5–45 μg/kg and 8–25 μg/kg, respectively. The method developed for the first time has high sensitivity, can be used as an effective tool for rapid screening and highly sensitive multiresidue determination of CYRO, MM and their metabolites AMD, AMN, and CA as well as DCD in milk powder samples.     

Effects of the combined action of axial and transversal loads on the failure time of a wooden beam under fire

This paper presents the variations of the failure time of a wooden beam (Baillonella toxisperma also called Moabi) in fire subjected to the combined effect of axial and transversal loads. Using the recommendation of the structural Eurocodes that the failure can occur when the deflection attains 1/300 of the length of the beam or when the bending moment attains the resistant moment, the partial differential equation describing the beam dynamics is solved numerically and the failure time calculated. It is found that the failure time decreases when either the axial or transversal loads increases.