Bulletin of Materials Science最新文献

Despite the low levels of copper ions in aquatic environments, excessive concentrations of copper ions can eventually cause serious harm to animals and humans as they are biologically enriched and ecologically cycled. Herein, an appropriate and selective separating material for copper ions with low concentrations needs to be developed. In the present work, bayberry tannin-modified chitosan fibres (TMF) were fabricated for selective removal of Cu²⁺. The adjacent phenolic hydroxyl groups at the B ring of tannin enable them to chelate with heavy metal ions, while the fibre structure of chitosan is conducive to the extended distribution of the active sites. It showed an adsorption capacity of 14.98 mg g^–1 for Cu²⁺ at 303 K, which was higher than that of most conventional adsorbents and activated carbon. Moreover, in the presence of co-existing heavy metal ions, including Ni²⁺, Cd²⁺, Fe³⁺ and Cr³⁺, we found that TMF showed highly selective adsorption of Cu²⁺, with Cu²⁺ concentrations as low as 5 mg l^–1. The TMF can be robustly recycled through acid treatment with 96.6% desorption efficiency.

The inhibitive property of hydroxypropyl methylcellulose (HPC) on acid (1.0 M HCl and 0.5 M H₂SO₄) corrosion of copper was investigated using gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and computational simulation techniques. Gravimetric results showed decrease in weight loss in the presence of HPC at room temperature of 25°C. With increase in temperature from 30–60°C, weight gain was observed which indicates that HPC film was adsorbed on the Cu surface. According to impedance measurement results, HPC displayed better inhibition in the presence of HCl (I.E._Rct% = 23.99) than in the presence of H₂SO₄ with 19.98 inhibition efficiency. Potentiodynamic polarization tests showed HPC inhibited HCl solution with I.E.% of 43.69 whereas 19.05 I.E.% was obtained for HPC in H₂SO₄ acid solution. Nonetheless, HPC acted as a mixed-type inhibitor with predominant cathodic effect. The DFT calculations showed that E_Homo is − 5.504 eV, while E_Lumo is 0.859 eV and energy gap is 6.363 eV. These values indicate that HPC inhibitor molecules are highly reactive and can readily transfer as well as accept electrons during copper surface-inhibitor interactions. Molecular dynamics simulation showed the adsorption energy (E_ads) for HPC on copper in the presence of 0.5 M H₂SO₄ solution was determined to be − 1.277 kcal/mol (− 5.108 kJ/mol), while E_ads for HPC on copper in the presence of 1.0 M HCl solution was − 1.55 kcal/mol (− 6.485 kJ/mol). The higher negative value of E_ads for HPC in the presence of HCl indicates stronger adsorption. Based on the observed results, HPC could be used as corrosion inhibitor for protection against corrosion of copper in 0.5 M H₂SO₄ acid solution but better in 1.0 M HCl acid solution.

Morphology-controlled catalyst nanoparticles have attracted significant research interest owing to their fundamental and scientific importance. In particular, their crystallographic orientation dependent properties greatly impact their electrocatalytic activity towards the oxygen reduction and evolution reactions. Herein, a CdMn₂O₄ catalyst with silk cocoon-shaped particles is synthesised via a solvothermal approach, and its bifunctional electrocatalytic activity in Zn–air batteries is studied. The catalyst is composed of three-dimensionally interconnected nanoparticles, which provide a highly accessible coordination environment around its surface, and a large number of exposed active sites. Compared with commercial 20 wt% Pt/C and IrO₂ catalysts, the CdMn₂O₄ catalyst exhibits a significantly reduced charge−discharge voltage gap, superior cycling stability and higher round-trip efficiency. Electrochemical redox species are present on the cocoon-shaped catalyst surface without perturbing its structure, and increase the number of reactive sites formed by defective O₂⁻ species, thereby providing sufficient structural stability. This work provides a new understanding that can aid in the design of highly efficient bifunctional electrocatalysts and structural engineering of silk cocoon-shaped materials to replace noble-metal catalysts or non-noble spinel electrocatalysts for Zn–air batteries.

Graphical Abstract

Iron tellurate–hematite nanocomposite was obtained by the thermal decomposition of organotellurium ferrocenecarboxylate. XRD study revealed that the composite has 68% tetragonal Fe₂TeO₆ phase and 32% trigonal α-Fe₂O₃ phase. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirm the chemical homogeneity of the nanocomposite. During the thermal decomposition of the precursor, tellurium segregates out in amorphous form resulting in a proportionate amount of α-Fe₂O₃ phase. Room temperature Mössbauer spectrum reveals that Fe is in +3 state in the nanocomposite. The bulk magnetization study reveals room temperature ferromagnetic order in the nanocomposite.

Accumulation of water in large diesel storage tanks due to climatic differences poses significant operational challenges, including potential contamination of tanker deliveries and the growth of harmful microbes leading to filter blockages and vehicle malfunctions. To mitigate this issue, we focus on the synthesis of biodegradable surfactants capable of emulsifying free water to form stable emulsions. Among various classes of biodegradable surfactants tested, oleic acid diethanolamide emerged as a promising candidate due to its superior emulsifying properties and relatively unexplored potential. To assess the maximum water emulsification, oleic acid diethanolamide was synthesised by optimising the ratio of oleic acid to diethanolamine. Out of the prepared formulations, a clear emulsion was achieved at a 1:1 ratio of oleic acid to diethanolamine, demonstrating higher efficacy in water emulsification compared to other formulations. Characterization analyses, including FTIR and total acid number, were conducted for all surfactants. Formulations utilising the synthesised surfactant at varying concentrations, ranging from 1 to 10% were used to stabilise 5% water in the emulsions. The study demonstrated that clear emulsions showed extended stability beyond 45 days with formulations having surfactant concentrations ranging from 6 to 10%. The emulsions were further characterized for key fuel properties such as calorific value, viscosity and cloud point to meet the operational requirements of the fuel. The research aims to provide a sustainable, environment friendly and operationally efficient solution to the persistent problem of water precipitation in large diesel storage tanks, offering operational efficiency and environmental benefits to the fuel industry.

In engineering projects involving expansive clay, its mechanical and chemical properties are enhanced through soil stabilization using various admixtures such as fly ash, lime, and cement. Considering the admixture’s limitation in recent years, the employment of waste materials in stabilizing such soils is highly encouraged. This study investigates the efficacy of digestate ash as a soil stabilizer under diverse temperature conditions (100°C to 800°C) through an unconfined compressive strength test at an optimal stabilizer content. The Atterberg’s limits and compressive strength test were performed on the clay with and without additives at room temperature through various curing times (0 and 28 days). The digestate ash was used at 0 to 25% (by dry clay weight) as an additive along with the initial consumption of lime as an activator at 4.5% (by dry soil weight). The maximum unconfined compressive strength value of 336 kPa was observed when using 15% digestate ash obtained at 560°C for a curing period of 28-days. The significant alteration in mineralogical and chemical composition was identified when the DA-modified clay underwent X-ray diffraction and fourier transform infrared examinations. This research facilitates better understanding of digestate ash-based soil stabilization in different thermal conditions, aiding sustainable soil improvement in civil engineering and environmental remediation.

A nano-sized Al₂O₃/MGO composite was studied for its ability to activate peroxymonosulphate (PMS) and generate active radicals for the degradation of ciprofloxacin (CIP). Degradation tests were performed at pH 7 with a CIP concentration of 20 mg × l⁻¹, the Al₂O₃/MGO dose of 2.0 g·l⁻¹, and the PMS dose of 2.0 g·l⁻¹. In addition, the degradation of CIP and the stability of the Al₂O₃/MGO-activated-PMS system were consistent after three repeated experiments. Furthermore, sulphate radicals (({text{SO}}_{4}^{ - bullet})) and hydroxyl radicals ((^{bullet})OH) were detected during the degradation of CIP, leading to the formation of nine degradation intermediates. Additionally, two possible degradation pathways were proposed. The results of this study suggests a new mechanism for the degradation of CIP in Al₂O₃/MGO-activated-PMS system, which could be applied to sulphate radicals (({text{SO}}_{4}^{ - bullet})) advanced oxidation processes (SR-AOPs).

In order to further improve the corrosion resistance of 316L stainless steel, which is commonly used in petrochemical enterprises, this paper leverages the characteristics of electrochemical deposition, utilizing pulsed-assisted jet electrodeposition technology. The morphology, hardness, wear resistance and corrosion resistance of the Ni-SiC composite coatings were investigated using scanning electron microscopy, X-ray diffractometer, energy-dispersive spectroscopy, a Vickers hardness tester, a friction and wear tester and an electrochemical workstation. The results indicate that deposition temperature influences coating properties more significantly than other factors. At a deposition temperature of 40°C, the coating exhibits minimal surface defects and the highest SiC particle content. At this time, the microhardness of the composite coatings reaches 652.85 HV, which is increased by 113.75% compared with the substrate, and the minima of the average friction coefficient and the average wear width are 0.73 and 383.6 μm, respectively, which are 4.13 and 40% lower than those of the substrate. In addition, the corrosion current density and annual corrosion rate of the composite coatings were reduced by 67.01 and 67.13%, respectively, compared to the substrate at this temperature. The study indicates that variations in deposition temperature significantly influence the wear and corrosion resistance of nickel-based composite coatings.

NiO were prepared by hydrothermal method using nitrate hexahydrate and urea as precursors at 100°C for 12 h. The morphology, size and structure was observed by scanning electron microscope and X-ray diffraction (XRD). The gas sensitivity of NiO to ethanol vapor was characterized by CGS-8 gas sensing analysis system. The results showed that the sensitivity of NiO-based gas sensor increased from 1.82 to 3.25 under the additive of polyvinylidene fluoride (PVDF). The mechanism of the enhanced gas sensing performance was investigated.