Materials

13 pages, 1140 KiB

Open AccessArticle

Multiwall Carbon Nanotubes/Spherical Glassy Carbon as Environmentally Friendly Adsorption Materials Utilized in Adsorptive Stripping Voltammetry for the Determination of Trace Amounts of Ga(III)

by Malgorzata Grabarczyk, Marzena Fialek and Edyta Wlazlowska

Materials 2024, 17(4), 966; https://doi.org/10.3390/ma17040966 - 19 Feb 2024

Cited by 1 | Viewed by 1023

Abstract

This work presents a proposal for an adsorptive stripping voltammetric (AdSV) method for gallium(III) determination at an eco-friendly multiwall carbon nanotube/spherical glassy carbon (MWCNT/SGC) electrode modified with a lead film. The operational factors influencing the sensitivity of the AdSV procedure were thoroughly investigated, [...] Read more.

This work presents a proposal for an adsorptive stripping voltammetric (AdSV) method for gallium(III) determination at an eco-friendly multiwall carbon nanotube/spherical glassy carbon (MWCNT/SGC) electrode modified with a lead film. The operational factors influencing the sensitivity of the AdSV procedure were thoroughly investigated, and their most favorable values were chosen (0.1 mol L⁻¹ acetate buffer solution pH = 5.6; 7 × 10⁻⁵ mol L⁻¹ Pb(II); 2 × 10⁻⁴ mol L⁻¹ cupferron; potential/time of lead film formation: −1.9 V/30 s; potential/time of Ga(III)–cupferron adsorption: −0.75 V/30 s). The newly developed MWCNT/SGCE has proven to be a competitive substrate to the glassy carbon electrode to create a lead film electrode, since it allows the determination of gallium in a wider range of concentrations from 3 × 10⁻⁹ to 4 × 10⁻⁷ mol L⁻¹ with a lower limit of detection equal to 9.5 × 10⁻¹⁰ mol L⁻¹. The elaborated procedure has been shown to be highly selective and insensitive to the presence of an even 100-fold excess of most of the ions commonly found in environmental waters. The MWCNT/SGC sensor, which can maintain >95% of its original response after 70 days of use, has been successfully applied for the detection of gallium in water samples with the relative standard deviation (RSD) ranging from 4.5% to 6.2% (n = 3) and recoveries in the range from 95.3% to 104.9%. Full article

(This article belongs to the Special Issue Environmentally Friendly Adsorption Materials)

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44 pages, 14513 KiB

Open AccessEditor’s ChoiceReview

Hydrogen Impact: A Review on Diffusibility, Embrittlement Mechanisms, and Characterization

by Qidong Li, Hesamedin Ghadiani, Vahid Jalilvand, Tahrim Alam, Zoheir Farhat and Md. Aminul Islam

Materials 2024, 17(4), 965; https://doi.org/10.3390/ma17040965 - 19 Feb 2024

Cited by 9 | Viewed by 3620

Abstract

Hydrogen embrittlement (HE) is a broadly recognized phenomenon in metallic materials. If not well understood and managed, HE may lead to catastrophic environmental failures in vessels containing hydrogen, such as pipelines and storage tanks. HE can affect the mechanical properties of materials such [...] Read more.

Hydrogen embrittlement (HE) is a broadly recognized phenomenon in metallic materials. If not well understood and managed, HE may lead to catastrophic environmental failures in vessels containing hydrogen, such as pipelines and storage tanks. HE can affect the mechanical properties of materials such as ductility, toughness, and strength, mainly through the interaction between metal defects and hydrogen. Various phenomena such as hydrogen adsorption, hydrogen diffusion, and hydrogen interactions with intrinsic trapping sites like dislocations, voids, grain boundaries, and oxide/matrix interfaces are involved in this process. It is important to understand HE mechanisms to develop effective hydrogen resistant strategies. Tensile, double cantilever beam, bent beam, and fatigue tests are among the most common techniques employed to study HE. This article reviews hydrogen diffusion behavior, mechanisms, and characterization techniques. Full article

(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials (2nd Edition))

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20 pages, 8413 KiB

Open AccessArticle

Enhancing Strength and Quantifying Sustainability of Building Blocks Manufactured by Geopolymerization

by Khadija Mawra, Khuram Rashid, Muhammad Irfan-ul-Hassan, Idrees Zafar and Mounir Ltifi

Materials 2024, 17(4), 964; https://doi.org/10.3390/ma17040964 - 19 Feb 2024

Cited by 3 | Viewed by 1050

Abstract

Enhancing the strength of fly ash (FA)-based geopolymer by increasing the alkaline activator content is a costly and unsustainable technique. Therefore, this work was designed to reduce the activator by employing the pressured catalysis (PC) technique, coupled with the use of minerals that [...] Read more.

Enhancing the strength of fly ash (FA)-based geopolymer by increasing the alkaline activator content is a costly and unsustainable technique. Therefore, this work was designed to reduce the activator by employing the pressured catalysis (PC) technique, coupled with the use of minerals that have filler and occupying effects. The main objective was to enhance the strength of the mix with a lower alkaline-to-precursor (A/P) ratio and create a sustainable, load-bearing building block from it. Initially, the compressive strength of the FA-based geopolymer was investigated experimentally by varying sodium silicate to sodium hydroxide and A/P ratios with ambient and hot curing. Afterward, PC was applied to the optimized proportion of constituents, and a significant increase in strength (9.6 to 20.0 Mpa) was observed at a 0.25 A/P ratio. By adding clay and dune sand (DS), the compressive strength was 19.5 and 40.4 Mpa at an A/P of 0.25 and 0.16, respectively. The strength gain mechanism was evaluated at the molecular and micro levels by conducting FTIR and SEM analyses. The environmental and economic indices and strength indicated the high sustainability of DS-based geopolymers compared to analogous blocks. The environmental and economic benefits of 23.9% reduced CO₂ emissions and 24.2% less cost were provided by the DS-based block compared to the FA–clay-based block. A DS-based geopolymer obtains strength at a low A/P due to its occupying effect and results in sustainable building blocks. Full article

(This article belongs to the Section Construction and Building Materials)

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21 pages, 7109 KiB

Open AccessArticle

Investigation of the Mechanical Behaviors and Damage Mechanism of C/C Composites Impacted by High-Velocity Jets

by Yifan Yue, Bo Wang, Kefei Yan, Renxi Zhao, Chengyu Zhang and Yulong Li

Materials 2024, 17(4), 963; https://doi.org/10.3390/ma17040963 - 19 Feb 2024

Viewed by 1146

Abstract

Carbon/Carbon (C/C) composites exhibit excellent mechanical properties at high temperatures, making them widely used in aerospace, such as the leading edges of spaceplane wings and the nose cones of hypersonic aircraft. However, damage caused by rain erosion to C/C composites affects their mechanical [...] Read more.

Carbon/Carbon (C/C) composites exhibit excellent mechanical properties at high temperatures, making them widely used in aerospace, such as the leading edges of spaceplane wings and the nose cones of hypersonic aircraft. However, damage caused by rain erosion to C/C composites affects their mechanical properties and poses significant challenges during operational service periods. A jet impingement test platform was employed to conduct single and multiple water-jet erosion tests on three-dimensional orthogonal C/C composite materials and to investigate the residual mechanical properties of the specimens after jet impact. The damage was characterized using optical microscopy, scanning electron microscopy, and X-ray computed tomography. The results showed that the damage types of the C/C composite materials under water-jet impingement included fiber bundle fracturing, delamination, and debonding. The extent of erosion damage was positively correlated with the jet velocity and diameter. The changes in the multi-jet damage indicated a cumulative expansion process, and z-directional fiber bundles exhibited superior resistance to jet impact damage propagation. The results of the three-point bending tests showed that the greater the initial impact damage, the lower the residual mechanical properties of the materials, and the residual strength of the specimen suddenly decreased when damage occurred at the back of the specimen. Full article

(This article belongs to the Section Advanced Composites)

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23 pages, 8131 KiB

Open AccessArticle

Active Acoustic Metamaterial Based on Helmholtz Resonators to Absorb Broadband Low-Frequency Noise

by Reza Hedayati and Sandhya P. Lakshmanan

Materials 2024, 17(4), 962; https://doi.org/10.3390/ma17040962 - 19 Feb 2024

Cited by 1 | Viewed by 1538

Abstract

The aim of the present work is to design active acoustic metamaterial consisting of an array of Helmholtz resonators and fabricating them using an additive manufacturing technique in order to assist in a reduction in noise levels in aerospace applications. To this aim, [...] Read more.

The aim of the present work is to design active acoustic metamaterial consisting of an array of Helmholtz resonators and fabricating them using an additive manufacturing technique in order to assist in a reduction in noise levels in aerospace applications. To this aim, initially, a passive metamaterial consisting of an array of 64 Helmholtz resonator unit cells is designed and tested to establish the effectiveness and region of performance. The selected design variable for change is identified as the resonator cavity depth through the frequency response for each parameter of the Helmholtz resonance equation and randomized to achieve a broadband frequency range of the passive metamaterial. An active model of this design (actuated by a stepper motor) is fabricated and tested. The metamaterials are tested under two acoustic set-ups: a closed system aimed at recreating the environment of a soundproof room and an open-system aimed to recreate the condition of an active liner. For the case of passive system, the metamaterial gave sound attenuation of 18 dB (for f = 150 Hz) in open system configuration and 33 dB (f = 350 Hz) in closed system configuration. The attenuation obtained for the active model was 10–15 dB over the mean line performance for the case of closed system and 15–20 dB for the case of open system. The closed system was also tested for performance at multiple cavity depths by setting two wall depths at 10 mm and three walls at 50 mm. This test yielded an attenuation of 15 dB at 180 Hz, the frequency corresponding to 50 mm cavity depth, and 10 dB at 515 Hz, corresponding to 10 mm cavity depth. Full article

(This article belongs to the Special Issue Acoustic and Mechanical Metamaterials: Recent Advances)

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21 pages, 24169 KiB

Open AccessArticle

A Novel Sandwich-Structured Phase Change Composite with Efficient Photothermal Conversion and Electromagnetic Interference Shielding Interface

by Jun Xu, Yuanyuan Li, Zhangxinyu Zhou and Xiaomin Cheng

Materials 2024, 17(4), 961; https://doi.org/10.3390/ma17040961 - 19 Feb 2024

Viewed by 957

Abstract

Stability and multifunctionality greatly extend the applications of phase change materials (PCMs) for thermal storage and management. Herein, CuS and Fe₃O₄ nanoparticles were successfully loaded onto cotton-derived carbon to develop a multifunctional interface with efficient photothermal conversion and electromagnetic interference [...] Read more.

Stability and multifunctionality greatly extend the applications of phase change materials (PCMs) for thermal storage and management. Herein, CuS and Fe₃O₄ nanoparticles were successfully loaded onto cotton-derived carbon to develop a multifunctional interface with efficient photothermal conversion and electromagnetic interference (EMI) shielding properties. 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol (DMDBS) and expanded graphite (EG) formed an organic/inorganic three-dimensional network framework to encapsulate 1-octadecanol (OD) by self-assembly. Finally, multifunctional shape-stabilized PCMs (SSPCMs) with the sandwich structure were prepared by the hot-press process. Multifunctional SSPCMs with high load OD (91%) had favorable thermal storage density (200.6 J/g), thermal stability, and a relatively wider available temperature range with improved thermal conductivity to support the thermal storage and management realization. Furthermore, due to the synergistic enhancement of two nanoparticles and the construction of the carbon network with cotton carbon and EG, highly efficient photothermal conversion (94.4%) and EMI shielding (68.9 dB average, X-band) performance were achieved at about 3 mm thickness, which provided the possibility of the multifunctional integration of PCMs. Conclusively, this study provides new insights towards integrating solar energy utilization with the comprehensive protection of related electronics. Full article

(This article belongs to the Special Issue Phase Change Materials (PCM) for Thermal Energy Storage)

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16 pages, 11048 KiB

Open AccessArticle

Development and Validation of Computational Fluid Dynamics Model of Ladle Furnace with Electromagnetic Stirring System

by Monika Zielinska, Hongliang Yang, Lukasz Madej and Lukasz Malinowski

Materials 2024, 17(4), 960; https://doi.org/10.3390/ma17040960 - 19 Feb 2024

Viewed by 957

Abstract

Numerical methods are crucial to supporting the development of new technology in different industries, especially steelmaking, where many phenomena cannot be directly measured or observed under industrial conditions. As a result, further designing and optimizing steelmaking equipment and technology are not easy tasks. [...] Read more.

Numerical methods are crucial to supporting the development of new technology in different industries, especially steelmaking, where many phenomena cannot be directly measured or observed under industrial conditions. As a result, further designing and optimizing steelmaking equipment and technology are not easy tasks. At the same time, numerical approaches enable modeling of various phenomena controlling material behavior and, thus, understanding the physics behind the processes occurring in different metallurgical devices. With this, it is possible to design and develop new technological solutions that improve the quality of steel products and minimize the negative impact on the environment. However, the usage of numerical approaches without proper validation can lead to misleading results and conclusions. Therefore, in this paper, the authors focus on the development of the CFD-based (computational fluid dynamics) approach to investigate the liquid steel flow inside one metallurgical device, namely a ladle furnace combined with an EMS (electromagnetic stirring) system. First, a numerical simulation of electromagnetic stirring in a scaled mercury model of a ladle furnace was carried out. The numerical results, such as stirring speed and turbulent kinetic energy, were compared with measurements in the mercury model. It was found that the results of the transient multiphase CFD model achieve good agreement with the measurements, but a free surface should be included in the CFD model to simulate the instability of the flow pattern in the mercury model. Based on the developed model, a full-scale industrial ladle furnace with electromagnetic stirring was also simulated and presented. This research confirms that such a coupled model can be used to design new types of EMS devices that improve molten steel flow in metallurgical equipment. Full article

(This article belongs to the Special Issue Advanced Metallurgy Technologies: Physical and Numerical Modelling)

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16 pages, 8344 KiB

Open AccessArticle

On optimization of Spin-Forming Process Parameters for Magnesium Alloy Wheel Hub Based on Gray Relational Analysis

by Zheng Zhang, Yongting Lan, Haochuan Ding and Yuanhang Xie

Materials 2024, 17(4), 959; https://doi.org/10.3390/ma17040959 - 19 Feb 2024

Viewed by 850

Abstract

To study the influencing factors of process parameters on the wall thickness deviation and internal warpage deviation of the workpiece in magnesium alloy wheel hub spin molding, a two-pass heterogeneous spin molding model is proposed. To ensure the accuracy of the simulation results, [...] Read more.

To study the influencing factors of process parameters on the wall thickness deviation and internal warpage deviation of the workpiece in magnesium alloy wheel hub spin molding, a two-pass heterogeneous spin molding model is proposed. To ensure the accuracy of the simulation results, the stress–strain data of AZ31 magnesium alloy at different temperatures and different strain rates were obtained through tests. Wall thickness deviation and internal warp deviation after molding were used as evaluation indexes of workpiece molding quality. ABAQUS software facilitated the numerical simulation and analysis of the magnesium alloy wheel hub spinning process. Gray relational degree analysis optimized the first-pass process parameters, elucidating the impact of the axial offset, the thinning ratio, and the feed ratio on forming quality. The application of optimized parameters in the hub spinning simulation resulted in a substantial 28.84% reduction in wall thickness deviation and a 4.88% reduction in inner diameter deviation. This study underscores the efficacy of employing Gray Relational Analysis for comprehensive parameter optimization, ensuring wheel hub quality. Moreover, it provides a theoretical foundation for enterprises to expedite research and development cycles and minimize associated costs. Full article

(This article belongs to the Special Issue Advanced Metal Forming Processes II)

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16 pages, 4515 KiB

Open AccessArticle

A Modified DF2016 Criterion for the Fracture Modeling from Shear to Equibiaxial Tension

by Xiaona Xu, Ruqiang Yan and Xucheng Fang

Materials 2024, 17(4), 958; https://doi.org/10.3390/ma17040958 - 19 Feb 2024

Cited by 1 | Viewed by 703

Abstract

This study introduces a modified DF2016 criterion to model a ductile fracture of sheet metals from shear to equibiaxial tension. The DF2016 criterion is modified so that a material constant is equal to the fracture strain at equibiaxial tension, which can be easily [...] Read more.

This study introduces a modified DF2016 criterion to model a ductile fracture of sheet metals from shear to equibiaxial tension. The DF2016 criterion is modified so that a material constant is equal to the fracture strain at equibiaxial tension, which can be easily measured by the bulging experiments. To evaluate the performance of the modified DF2016 criterion, experiments are conducted for QP980 with five different specimens with stress states from shear to equibiaxial tension. The plasticity of the steel is characterized by the Swift–Voce hardening law and the pDrucker function, which is calibrated with the inverse engineering approach. A fracture strain is measured by the XTOP digital image correlation system for all the specimens, including the bulging test. The modified DF2016 criterion is also calibrated with the inverse engineering approach. The predicted force–stroke curves are compared with experimental results to evaluate the performance of the modified DF2016 criterion on the fracture prediction from shear to equibiaxial tension. The comparison shows that the modified DF2016 criterion can model the onset of the ductile fracture with high accuracy in wide stress states from shear to plane strain tension. Moreover, the calibration of the modified DF2016 criterion is comparatively easier than the original DF2016 criterion. Full article

(This article belongs to the Special Issue Characterizations, Mechanical Properties and Constitutive Modeling of Advanced Materials)

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16 pages, 3387 KiB

Open AccessArticle

Investigation of the Photocatalytic Performance, Mechanism, and Degradation Pathways of Rhodamine B with Bi₂O₃ Microrods under Visible-Light Irradiation

by Dechong Ma, Jiawei Tang, Guowen He and Sai Pan

Materials 2024, 17(4), 957; https://doi.org/10.3390/ma17040957 - 19 Feb 2024

Cited by 2 | Viewed by 1081

Abstract

In the present work, the photodegradation of Rhodamine B with different pH values by using Bi₂O₃ microrods under visible-light irradiation was studied in terms of the dye degradation efficiency, active species, degradation mechanism, and degradation pathway. X-ray diffractometry, polarized optical [...] Read more.

In the present work, the photodegradation of Rhodamine B with different pH values by using Bi₂O₃ microrods under visible-light irradiation was studied in terms of the dye degradation efficiency, active species, degradation mechanism, and degradation pathway. X-ray diffractometry, polarized optical microscopy, scanning electron microscopy, fluorescence spectrophotometry, diffuse reflectance spectra, Brunauer–Emmett–Teller, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, UV–visible spectrophotometry, total organic carbon, and liquid chromatography–mass spectroscopy analysis techniques were used to analyze the crystal structure, morphology, surface structures, band gap values, catalytic performance, and mechanistic pathway. The photoluminescence spectra and diffuse reflectance spectrum (the band gap values of the Bi₂O₃ microrods are 2.79 eV) reveals that the absorption spectrum extended to the visible region, which resulted in a high separation and low recombination rate of electron–hole pairs. The photodegradation results of Bi₂O₃ clearly indicated that Rhodamine B dye had removal efficiencies of about 97.2%, 90.6%, and 50.2% within 120 min at the pH values of 3.0, 5.0, and 7.0, respectively. In addition, the mineralization of RhB was evaluated by measuring the effect of Bi₂O₃ on chemical oxygen demand and total organic carbon at the pH value of 3.0. At the same time, quenching experiments were carried out to understand the core reaction species involved in the photodegradation of Rhodamine B solution at different pH values. The results of X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffractometer analysis of pre- and post-Bi₂O₃ degradation showed that BiOCl was formed on the surface of Bi₂O₃, and a BiOCl/Bi₂O₃ heterojunction was formed after acid photocatalytic degradation. Furthermore, the catalytic degradation of active substances and the possible mechanism of the photocatalytic degradation of Rhodamine B over Bi₂O₃ at different pH values were analyzed based on the results of X-ray diffractometry, radical capture, Fourier-transform infrared spectroscopy, total organic carbon analysis, and X-ray photoelectron spectroscopy. The degradation intermediates of Rhodamine B with the Bi₂O₃ photocatalyst in visible light were also identified with the assistance of liquid chromatography–mass spectroscopy. Full article

(This article belongs to the Special Issue Advanced Nanostructured Materials for Catalytic Applications)

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20 pages, 12636 KiB

Open AccessArticle

Equation of State of Autoclaved Aerated Concrete–Oedometric Testing

by Yuri S. Karinski, Vladimir R. Feldgun and David Z. Yankelevsky

Materials 2024, 17(4), 956; https://doi.org/10.3390/ma17040956 - 19 Feb 2024

Viewed by 805

Abstract

This paper aims at investigating the triaxial behavior of Autoclaved Aerated Concrete (AAC) under extremely high pressures, and experimentally determine Equation of State (EOS) for several different AAC densities. Oedometric tests were carried out using a home-made high-pressure triaxial apparatus, and pressures up [...] Read more.

This paper aims at investigating the triaxial behavior of Autoclaved Aerated Concrete (AAC) under extremely high pressures, and experimentally determine Equation of State (EOS) for several different AAC densities. Oedometric tests were carried out using a home-made high-pressure triaxial apparatus, and pressures up to ~500 MPa were applied. The complete pressure-bulk strain relationships were measured, and new findings and insights were obtained. The paper presents the testing set-up and the measurement system. The data processing method accounting for the AAC pronounced shortening during the ongoing test is described using a weighted functions procedure for the circumferential strains’ calculation, with which the confining pressure was determined. The boundary conditions effects on the test results were investigated, and a new technique for specimen insulation was suggested to ensure loading without friction and the prevention of local shear failure. The experimental EOS for different AAC densities were obtained. EOS curves for different specimens with the same density demonstrated good to very good repeatability of the EOS curves over the entire pressure range. Based on the tests results and the density’s span, three classes of AAC are proposed. A preliminary attempt to apply the newly obtained EOS curves has been carried out to examine the energy dissipation for three different dynamic load levels. Although this is a preliminary stage that is beyond the objective of this paper, early interesting results were observed where an optimal AAC density, for which the highest energy has been absorbed, was identified. This finding encourages inclusion of that preliminary study as a closure section. Numerical simulations of wave propagation through ACC layers of different densities, laid on rigid supporting slabs, was carried out. The minimum total impulse imparted to the rigid slab was found for the optimal AAC density that has been determined above. Full article

(This article belongs to the Special Issue Concrete in Structural Engineering: Fabrication and Mechanical Behavior ‖)

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25 pages, 9658 KiB

Open AccessReview

Recent Advances in Molten Salt-Based Nanofluids as Thermal Energy Storage in Concentrated Solar Power: A Comprehensive Review

by Fahim Mahtab Abir, Qutaiba Altwarah, Md Tasnim Rana and Donghyun Shin

Materials 2024, 17(4), 955; https://doi.org/10.3390/ma17040955 - 19 Feb 2024

Cited by 1 | Viewed by 1444

Abstract

This study critically reviews the key aspects of nanoparticles and their impact on molten salts (MSs) for thermal energy storage (TES) in concentrated solar power (CSP). It then conducts a comprehensive analysis of MS nanofluids, focusing on identifying the best combinations of salts [...] Read more.

This study critically reviews the key aspects of nanoparticles and their impact on molten salts (MSs) for thermal energy storage (TES) in concentrated solar power (CSP). It then conducts a comprehensive analysis of MS nanofluids, focusing on identifying the best combinations of salts and nanoparticles to increase the specific heat capacity (SHC) efficiently. Various methods and approaches for the synthesis of these nanofluids are explained. The article presents different experimental techniques used to characterize nanofluids, including measuring the SHC and thermal conductivity and analyzing particle dispersion. It also discusses the challenges associated with characterizing these nanofluids. The study aims to investigate the underlying mechanisms behind the observed increase in SHC in MS nanofluids. Finally, it summarizes potential areas for future research, highlighting crucial domains for further investigation and advancement. Full article

(This article belongs to the Special Issue Modeling and Simulation of Heat and Mass Transfer in Novel Low-Dimensional Nanomaterials)

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14 pages, 6576 KiB

Open AccessArticle

Green Synthesis and Efficient Adsorption: Na-X Zeolite vs. C/Mn/SiO₂ Composite for Heavy Metals Removal

by Magdalena Medykowska, Małgorzata Wiśniewska, Katarzyna Szewczuk-Karpisz, Mariia Galaburda, Olena Oranska and Rafał Panek

Materials 2024, 17(4), 954; https://doi.org/10.3390/ma17040954 - 19 Feb 2024

Cited by 1 | Viewed by 948

Abstract

The studies aimed to test the adsorption capacity of two silica-enriched porous materials, synthetic Na-X zeolite and Mn-containing carbon composite, towards Pb(II) and Zn(II) ions in single and mixed systems and in the presence of diclofenac (DCF) and (or) poly(acrylic acid) (PAA). The [...] Read more.

The studies aimed to test the adsorption capacity of two silica-enriched porous materials, synthetic Na-X zeolite and Mn-containing carbon composite, towards Pb(II) and Zn(II) ions in single and mixed systems and in the presence of diclofenac (DCF) and (or) poly(acrylic acid) (PAA). The synthetic zeolite was characterized by a well-developed surface area of 728 m²/g and a pore diameter of 1.73 nm, while the carbon composite exhibited 268 m²/g and 7.37 nm, respectively. Na-X was found to be more efficient than the carbon composite (75–212 mg/g) in adsorbing heavy metal ions in both single and bimetallic systems (322–333 mg/g). In turn, the C/Mn/SiO₂ composite was more effective in removing Pb(II) ions from the systems that simultaneously contained DCF or PAA (480 and 476 mg/g, respectively). The Na-X zeolite demonstrated the greatest stability in all the systems studied. The highest stability was observed in the DCF + Pb(II) mixture, in contrast to the carbon composites where the stability was much lower. To evaluate the possibility of regeneration of the solids, HCl proved to be the best desorbent for heavy metal ions (efficiency of 99%). In general, both adsorbents offer promising potential for solving environmental problems. Full article

(This article belongs to the Special Issue Recent Advances in the Environmental Remediation Using Zeolites and Other Adsorbent Materials)

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13 pages, 9090 KiB

Open AccessArticle

Design and Simulation of Tunneling Diodes with 2D Insulators for Rectenna Switches

by Evelyn Li, Parameswari Raju and Erhai Zhao

Materials 2024, 17(4), 953; https://doi.org/10.3390/ma17040953 - 19 Feb 2024

Cited by 1 | Viewed by 1364

Abstract

Rectenna is the key component in radio-frequency circuits for receiving and converting electromagnetic waves into direct current. However, it is very challenging for the conventional semiconductor diode switches to rectify high-frequency signals for 6G telecommunication (>100 GHz), medical detection (>THz), and rectenna solar [...] Read more.

Rectenna is the key component in radio-frequency circuits for receiving and converting electromagnetic waves into direct current. However, it is very challenging for the conventional semiconductor diode switches to rectify high-frequency signals for 6G telecommunication (>100 GHz), medical detection (>THz), and rectenna solar cells (optical frequencies). Such a major challenge can be resolved by replacing the conventional semiconductor diodes with tunneling diodes as the rectenna switches. In this work, metal–insulator–metal (MIM) tunneling diodes based on 2D insulating materials were designed, and their performance was evaluated using a comprehensive simulation approach which includes a density-function theory simulation of 2D insulator materials, the modeling of the electrical characteristics of tunneling diodes, and circuit simulation for rectifiers. It is found that novel 2D insulators such as monolayer TiO₂ can be obtained by oxidizing sulfur-metal layered materials. The MIM diodes based on such insulators exhibit fast tunneling and excellent current rectifying properties. Such tunneling diodes effectively convert the received high-frequency electromagnetic waves into direct current. Full article

(This article belongs to the Special Issue Novel Semiconductor Devices and Nanomaterials for Energy, Power and High-Frequency Applications)

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18 pages, 8096 KiB

Open AccessArticle

Quantitative Analysis of the Physical Properties of Ti6Al4V Powders Used in a Powder Bed Fusion Based on 3D X-ray Computed Tomography Images

by Yuyi Mao, Juan Hu, Qiang Chen and Xiaodong Shen

Materials 2024, 17(4), 952; https://doi.org/10.3390/ma17040952 - 19 Feb 2024

Viewed by 890

Abstract

The physical properties of Ti6Al4V powder affect the spreadability of the powder and uniformity of the powder bed, which had a great impact on the performance of built parts made by powder bed fusion technology. Micro-computed tomography is a well-established technique used to [...] Read more.

The physical properties of Ti6Al4V powder affect the spreadability of the powder and uniformity of the powder bed, which had a great impact on the performance of built parts made by powder bed fusion technology. Micro-computed tomography is a well-established technique used to analyze the non-destructivity of the objects’ interior. Ti6Al4V powders were scanned with micro-CT to show the internal and external information of all the particles. The morphology, particle size distribution, hollow particle ratio, density, inclusion, and specific surface area of the powder samples were quantitatively characterized, and the relationship of flowability with these physical properties was analyzed in this work. The research results of this article showed that micro-CT is an effective way to characterize these items, and can be developed as a standard method of powder physical properties in the future. Full article

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20 pages, 997 KiB

Open AccessArticle

Predicting Design Solutions with Scenarios Considering the Quality of Materials and Products Based on a Life Cycle Assessment (LCA)

by Dominika Siwiec and Andrzej Pacana

Materials 2024, 17(4), 951; https://doi.org/10.3390/ma17040951 - 19 Feb 2024

Cited by 2 | Viewed by 879

Abstract

The advancement of quality and environmentally sustainable materials and products made from them has improved significantly over the last few years. However, a research gap is the lack of a developed model that allows for the simultaneous analysis of quality and environmental criteria [...] Read more.

The advancement of quality and environmentally sustainable materials and products made from them has improved significantly over the last few years. However, a research gap is the lack of a developed model that allows for the simultaneous analysis of quality and environmental criteria in the life-cycle assessment (LCA) for the selection of materials in newly designed products. Therefore, the objective of the research was to develop a model that supports the prediction of the environmental impact and expected quality of materials and products made from them according to the design solution scenarios considering their LCA. The model implements the GRA method and environmental impact analysis according to the LCA based on ISO 14040. The model test was carried out for light passenger vehicles of BEV with a lithium-ion battery (LiFePO₄) and for ICEV. The results indicated a relatively comparable level of quality, but in the case of the environmental impact throughout the life-cycle, the predominant amount of CO₂ emissions in the use phase for combustion vehicles. The originality of the developed model to create scenarios of design solutions is created according to which the optimal direction of their development in terms of quality and environment throughout LCA can be predicted. Full article

(This article belongs to the Special Issue Materials Design, Manufacturing, Testing and Processes for Sustainability)

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18 pages, 5123 KiB

Open AccessReview

Vat Photopolymerization 3D Printing in Dentistry: A Comprehensive Review of Actual Popular Technologies

by Elisa Caussin, Christian Moussally, Stéphane Le Goff, Timothy Fasham, Max Troizier-Cheyne, Laurent Tapie, Elisabeth Dursun, Jean-Pierre Attal and Philippe François

Materials 2024, 17(4), 950; https://doi.org/10.3390/ma17040950 - 19 Feb 2024

Cited by 4 | Viewed by 1751

Abstract

In this comprehensive review, the current state of the art and recent advances in 3D printing in dentistry are explored. This article provides an overview of the fundamental principles of 3D printing with a focus on vat photopolymerization (VP), the most commonly used [...] Read more.

In this comprehensive review, the current state of the art and recent advances in 3D printing in dentistry are explored. This article provides an overview of the fundamental principles of 3D printing with a focus on vat photopolymerization (VP), the most commonly used technological principle in dental practice, which includes SLA, DLP, and LCD (or mSLA) technologies. The advantages, disadvantages, and shortcomings of these technologies are also discussed. This article delves into the key stages of the dental 3D printing process, from computer-aided design (CAD) to postprocessing, emphasizing the importance of postrinsing and postcuring to ensure the biocompatibility of custom-made medical devices. Legal considerations and regulatory obligations related to the production of custom medical devices through 3D printing are also addressed. This article serves as a valuable resource for dental practitioners, researchers, and health care professionals interested in applying this innovative technology in clinical practice. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials Studies for Oral Health)

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17 pages, 6136 KiB

Open AccessArticle

Calculation of and Key Influencing Factors Analysis on Equivalent Resilient Modulus of a Submerged Subgrade

by Junyao Tang, Siyu Chen, Tao Ma, Binshuang Zheng and Xiaoming Huang

Materials 2024, 17(4), 949; https://doi.org/10.3390/ma17040949 - 18 Feb 2024

Viewed by 791

Abstract

To calculate and analyze the equivalent resilient modulus of a submerged subgrade, a constitutive model considering the effect of saturation and matrix suction was introduced using ABAQUS’s user-defined material (UMAT)subroutine. The pavement response under falling weight deflectometer (FWD) load was simulated at various [...] Read more.

To calculate and analyze the equivalent resilient modulus of a submerged subgrade, a constitutive model considering the effect of saturation and matrix suction was introduced using ABAQUS’s user-defined material (UMAT)subroutine. The pavement response under falling weight deflectometer (FWD) load was simulated at various water levels based on the derived distribution of the resilient modulus within the subgrade. The equivalent resilient modulus of the subgrade was then calculated using the equivalent iteration and weighted average methods. Based on this, the influence of the material and structural parameters of the subgrade was analyzed. The results indicate that the effect of water level rise on the tensile strain at the bottom of the asphalt layer and the compressive strain at the top of the subgrade is obvious, and its trend is similar to an exponential change. The equivalent resilient modulus of the subgrade basically decreases linearly with the rise in the water level, and there is high consistency between the equivalent iteration and weighted average methods. The saturated permeability coefficient and subgrade height have the most significant effect on the resilient modulus of the subgrade, which should be emphasized in the design of submerged subgrades, and the suggested values of the resilient modulus of the subgrade should be proposed according to the relevant construction conditions. Full article

(This article belongs to the Special Issue Performance-Related Material Properties of Asphalt Mixture Components (Second Edition))

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18 pages, 17352 KiB

Open AccessArticle

Experimental Study on the Mechanical Properties of Disposable Mask Waste–Reinforced Gangue Concrete

by Yu Yang, Changhao Xin, Yidan Sun, Junzhen Di, Fankang Meng and Xinhua Zhou

Materials 2024, 17(4), 948; https://doi.org/10.3390/ma17040948 - 18 Feb 2024

Cited by 1 | Viewed by 1199

Abstract

This paper is grounded on the following information: (1) Disposable masks primarily consist of polypropylene fiber, which exhibits excellent flexibility. (2) China has extensive coal gangue deposits that pose a significant environmental hazard. (3) Coal gangue concrete exhibits greater fragility compared to regular [...] Read more.

This paper is grounded on the following information: (1) Disposable masks primarily consist of polypropylene fiber, which exhibits excellent flexibility. (2) China has extensive coal gangue deposits that pose a significant environmental hazard. (3) Coal gangue concrete exhibits greater fragility compared to regular concrete and demonstrates reduced resistance to deformation. With the consideration of environmental conservation and resource reutilization, a preliminary concept suggests the conversion of discarded masks into fibers, which can be blended with coal gangue concrete to enhance its mechanical characteristics. In this paper, the stress–strain law of different mask fiber–doped coal gangue concrete (DMGC) under uniaxial compression is studied when the matrix strength is C20 and C30, and the effect of mask fiber content on the mechanical behavior and energy conversion relationship of coal gangue concrete is analyzed. The experimental results show that when the content of mask fiber is less than 1.5%, the strength, elastic modulus, deformation resistance, and energy dissipation of the concrete increase with mask fiber content. When the amount of mask fiber is more than 1.5%, because the tensile capacity and energy dissipation level of concrete produced by the mask fiber cannot compensate for the compression and deformation resistance of concrete of the same quantity and because excess fiber is difficult to evenly mix in the concrete, there are pore defects in concrete, which decreases the concrete strength due to the increase in mask fiber. Therefore, adding less than 1.5% mask fiber helps to improve the ductility, toughness, impermeability, and oxidation and control the cracking of coal gangue concrete. Based on Weibull theory, a constitutive model of DMGC is established, which fits well with the results of a uniaxial test, providing support for understanding the mechanical law of mask fiber–doped concrete. Full article

(This article belongs to the Section Construction and Building Materials)

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12 pages, 4295 KiB

Open AccessArticle

A High-Efficiency Wideband Grating Coupler Based on Si₃N₄ and a Silicon-on-Insulator Heterogeneous Integration Platform

by Meng Liu, Xu Zheng, Xuan Zheng and Zisu Gong

Materials 2024, 17(4), 947; https://doi.org/10.3390/ma17040947 - 18 Feb 2024

Viewed by 1179

Abstract

To fully utilize the advantages of Si₃N₄ and Silicon-On-Insulator to achieve a high-efficiency wideband grating coupler, we propose and numerically demonstrate a grating coupler based on Si₃N₄ and a Silicon-On-Insulator heterogeneous integration platform. A two-dimensional model of [...] Read more.

To fully utilize the advantages of Si₃N₄ and Silicon-On-Insulator to achieve a high-efficiency wideband grating coupler, we propose and numerically demonstrate a grating coupler based on Si₃N₄ and a Silicon-On-Insulator heterogeneous integration platform. A two-dimensional model of the coupler was established and a comprehensive finite difference time domain analysis was conducted. Focusing on coupling efficiency as a primary metric, we examined the impact of factors such as grating period, filling factor, etching depth, and the thicknesses of the SiO₂ upper cladding, Si₃N₄, silicon waveguide, and SiO₂ buried oxide layers. The calculations yielded an optimized grating coupler with a coupling efficiency of 81.8% (−0.87 dB) at 1550 nm and a 1-dB bandwidth of 540 nm. The grating can be obtained through a single etching step with a low fabrication complexity. Furthermore, the fabrication tolerances of the grating period and etching depth were studied systematically, and the results indicated a high fabrication tolerance. These findings can offer theoretical and parameter guidance for the design and optimization of high-efficiency and broad-bandwidth grating couplers. Full article

(This article belongs to the Special Issue Micro-nano Optical Structure Materials and Their Applications)

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13 pages, 5535 KiB

Open AccessArticle

Multi-Physics Modeling of Melting-Solidification Characteristics in Laser Powder Bed Fusion Process of 316L Stainless Steel

by Xiuyang Shan, Zhenggao Pan, Mengdi Gao, Lu Han, Joon-Phil Choi and Haining Zhang

Materials 2024, 17(4), 946; https://doi.org/10.3390/ma17040946 - 18 Feb 2024

Cited by 2 | Viewed by 1270

Abstract

In the laser powder bed fusion process, the melting-solidification characteristics of 316L stainless steel have a great effect on the workpiece quality. In this paper, a multi-physics model was constructed using the finite volume method (FVM) to simulate the melting-solidification process of a [...] Read more.

In the laser powder bed fusion process, the melting-solidification characteristics of 316L stainless steel have a great effect on the workpiece quality. In this paper, a multi-physics model was constructed using the finite volume method (FVM) to simulate the melting-solidification process of a 316L powder bed via laser powder bed fusion. In this physical model, the phase change process, the influence of temperature gradient on surface tension of molten pool, and the influence of recoil pressure caused by the metal vapor on molten pool surface were considered. Using this model, the effects of laser scanning speed, hatch space, and laser power on temperature distribution, keyhole depth, and workpiece quality were studied. This study can be used to guide the optimization of process parameters, which is beneficial to the improvement of workpiece quality. Full article

(This article belongs to the Special Issue State of the Art in Materials for Additive Manufacturing)

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12 pages, 3584 KiB

Open AccessArticle

Research on the Formation Conditions and Preventive Measures of Uranium Precipitates during the Service Process of Medical Isotope Production Reactors

by Yanli Zhao, Yuan Gao, Xinyue Li, Yi Le, Yang Zhang, Jie Qiu and Yong Xin

Materials 2024, 17(4), 945; https://doi.org/10.3390/ma17040945 - 18 Feb 2024

Viewed by 717

Abstract

This study focuses on the Medical Isotope Production Reactor (MIPR), an aqueous homogeneous reactor utilized for synthesizing medical isotopes like ⁹⁹Mo. A pivotal aspect of MIPR’s functionality involves the fuel solution’s complex chemical interactions, particularly during reactor operation. These interactions result in [...] Read more.

This study focuses on the Medical Isotope Production Reactor (MIPR), an aqueous homogeneous reactor utilized for synthesizing medical isotopes like ⁹⁹Mo. A pivotal aspect of MIPR’s functionality involves the fuel solution’s complex chemical interactions, particularly during reactor operation. These interactions result in the formation of precipitates, notably water filamentous uranium ore and columnar uranium ore, which can impact reactor performance. The research presented here delves into the reactions between liquid fuel uranyl nitrate and key radiolytic products, employing simulation calculations complemented by experimental validation. This approach facilitates the identification of uranium precipitate types and their formation conditions under operational reactor settings. Additionally, the article explores strategies to mitigate the formation of specific uranium precipitates, thereby contributing to the efficient and stable operation of MIPR. Full article

(This article belongs to the Section Advanced Composites)

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19 pages, 5050 KiB

Open AccessArticle

Impact of High-Frequency Traveling-Wave Magnetic Fields on Low-Conductivity Liquids: Investigation and Potential Applications in the Chemical Industry

by Xinyu Cui, Xianzhao Na, Xiaodong Wang, Roland Ernst and Fautrelle Yves

Materials 2024, 17(4), 944; https://doi.org/10.3390/ma17040944 - 18 Feb 2024

Viewed by 946

Abstract

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. [...] Read more.

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. This article investigates the application and approaches of a unique form of high-frequency traveling-wave magnetic fields to low-conductivity liquids with conductivity ranging from 1 to 102 S/m. Experiments were conducted using four representative electrolytic solutions commonly employed in the chemical industry: sulfuric acid (H₂SO₄), sodium hydroxide (NaOH), sodium chloride (NaCl), and ionic liquid ([Bmim]BF₄). The investigation focuses on the impact of high-frequency magnetic fields on these solutions at the optimal operating point of the system, considering the effects of Joule heating. The findings reveal that the high-frequency traveling magnetic field exerts a significant volumetric force on all four low-conductivity liquids. This technology, characterized by its non-contact and pollution-free nature, high efficiency, large driving volume, and rapid driving speeds (up to several centimeters per second), also provides uniform velocity distribution and notable thermal effects. It holds considerable promise for applications in the chemical industry, metallurgy, and other sectors where enhanced three-phase transfer processes are essential. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

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15 pages, 22741 KiB

Open AccessArticle

Road Performance and Self-Healing Property of Bituminous Mixture Containing Urea–Formaldehyde Microcapsules

by Hongliang Zhang, Tong Yao and Fenglei Cheng

Materials 2024, 17(4), 943; https://doi.org/10.3390/ma17040943 - 18 Feb 2024

Viewed by 941

Abstract

Urea–formaldehyde (UF) is a common shell material for self-healing microcapsules; however, the influence of urea–formaldehyde microcapsules (UFMs) on the road performance of bituminous mixtures and the sensitivity of their healing abilities remains unclear. In this paper, UFMs were prepared via in situ polymerization [...] Read more.

Urea–formaldehyde (UF) is a common shell material for self-healing microcapsules; however, the influence of urea–formaldehyde microcapsules (UFMs) on the road performance of bituminous mixtures and the sensitivity of their healing abilities remains unclear. In this paper, UFMs were prepared via in situ polymerization (ISP), followed by an investigation into the road performance of UFM self-healing bituminous mixtures through various tests, including wheel tracking, immersed Marshall, freeze–thaw splitting, low-temperature bending, and three-point bending fatigue tests. Subsequently, the impact of the damage degree, healing duration, and temperature on the self-healing property was discussed. The results indicated that incorporating 3 wt% UFMs into bitumen significantly improved the high-temperature stability and fatigue resistance of the bituminous mixture; for example, its dynamic stability and fatigue life could be increased by about 16.5% and 10%, respectively. However, it diminished the thermal crack resistance, as evidenced by decreases in bending tensile strength and strain by 3.7% and 10.1%, respectively. And it did not markedly improve the moisture susceptibility. Additionally, the maximum improvement observed in the healing rate was about 9%. Furthermore, the healing duration and temperature positively influenced the bituminous mixture’s self-healing, whereas the degree of damage exerted a negative impact, with a relatively significant effect. Full article

(This article belongs to the Section Construction and Building Materials)

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18 pages, 5939 KiB

Open AccessArticle

Investigation into the Structure and Properties of Biochar Co-Activated by ZnCl₂ and NaHCO₃ under Low Temperature Conditions

by Hao Zhang, Zhaozhou Wei, Deyuan Xiong, Yao Wu, Menglong Tong, Huiping Su, Zuoyuan Zhang and Jian Liao

Materials 2024, 17(4), 942; https://doi.org/10.3390/ma17040942 - 18 Feb 2024

Cited by 1 | Viewed by 985

Abstract

Using sodium lignosulfonate as feedstock, ZnCl₂ and NaHCO₃ co-activated the hierarchical porous carbons (HPCs) were prepared by one-pot pyrolysis with different NaHCO₃ dosages (0–4 g) and carbonization temperatures (400–600 °C). Subsequently, phosphotungstate (HPW) was supported with the resulting biochar for [...] Read more.

Using sodium lignosulfonate as feedstock, ZnCl₂ and NaHCO₃ co-activated the hierarchical porous carbons (HPCs) were prepared by one-pot pyrolysis with different NaHCO₃ dosages (0–4 g) and carbonization temperatures (400–600 °C). Subsequently, phosphotungstate (HPW) was supported with the resulting biochar for the α-pinene hydration reaction to produce α-terpineol. The optimum preparation conditions were determined according to the yield of α-terpineol. The formation mechanism and physicochemical properties of HPCs were analyzed through TG, SEM, XPS, XRD, FT-IR, and N₂ adsorption–desorption isotherms. The results demonstrated that NaHCO₃ underwent a two-step reaction which liberated a substantial quantity of CO₂, thereby enhancing activated carbon’s macroporous and mesoporous structures. Simultaneously, NaHCO₃ mitigated strong acid gas (HCl) emissions during ZnCl₂ activation. Compared with AC450-4:8:0 prepared by ZnCl₂ activation alone, the total pore volume of AC450-4:8:2 prepared by co-activation is increased from 0.595 mL/g to 0.754 mL/g and the mesopore rate from 47.7% to 77.8%, which is conducive to reducing the steric hindrance of the hydration reaction and improving the selectivity. Hydration experiments show that the selectivity of α-terpineol is 55.7% under HPW/AC450-4:8:2 catalysis, higher than 31.0% for HPW and 47.4% for HPW/AC450-4:8:0. Full article

(This article belongs to the Section Carbon Materials)

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20 pages, 10346 KiB

Open AccessFeature PaperArticle

Assessing the Impact of Sepiolite-Based Bio-Pigment Infused with Indigo Extract on Appearance and Durability of Water-Based White Primer

by Massimo Calovi and Stefano Rossi

Materials 2024, 17(4), 941; https://doi.org/10.3390/ma17040941 - 18 Feb 2024

Viewed by 890

Abstract

The objective of this study is to evaluate how two varying amounts of sepiolite-based powder, infused with indigo extract, affect the appearance and durability of a water-based, white primer. To examine the influence of this eco-friendly pigment on the coatings’ overall appearance, assessments [...] Read more.

The objective of this study is to evaluate how two varying amounts of sepiolite-based powder, infused with indigo extract, affect the appearance and durability of a water-based, white primer. To examine the influence of this eco-friendly pigment on the coatings’ overall appearance, assessments were performed for color, gloss, and surface roughness. Additionally, the coatings were investigated through optical and electron microscopic observations, to evaluate the distribution of the pigment within the polymer matrix. The effect of the pigment on the coating’s durability was assessed through accelerated tests, including exposure in a salt spray chamber and a UV-B chamber. These tests aimed to evaluate the emergence of defects and changes in the appearance of the samples over time. Furthermore, the impact of different quantities of sepiolite-based powder on the coating’s ability to act as a barrier was assessed using liquid resistance tests and contact angle measurements. These evaluations aimed to understand how the coating responded to various liquids and its surface properties concerning repellency or absorption. In essence, this study underscores the considerable influence of the eco-friendly pigment, demonstrating its capacity to introduce unique color and texture variations in the paint. Moreover, the inclusion of the pigment has enhanced the coating’s color stability, its ability to act as a barrier, and its overall durability when exposed to harsh environments. Full article

(This article belongs to the Special Issue Food Industry Wastes and By-Products in Polymer Technology)

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2 pages, 460 KiB

Open AccessCorrection

Correction: Li et al. Liquid Regions of Lanthanum-Bearing Aluminosilicates. Materials 2020, 13, 450

by Yandong Li, Tongsheng Zhang, Yefeng Feng, Chengjun Liu and Maofa Jiang

Materials 2024, 17(4), 940; https://doi.org/10.3390/ma17040940 - 18 Feb 2024

Viewed by 560

Abstract

In the original publication [...] Full article

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13 pages, 5148 KiB

Open AccessArticle

Adsorption of Phosphate by Two-Step Synthesis of Ceramsite from Electrolytic Manganese Residue/Dredged Sludge

by Hao Cheng, Wei Shi, Song Liu, Yong Wang, Jia Song, Yu Long, Yuan Xiang and Yongjie Xue

Materials 2024, 17(4), 939; https://doi.org/10.3390/ma17040939 - 17 Feb 2024

Viewed by 1186

Abstract

Carrying out research on the management of electrolytic manganese residue (EMR) is necessary to maintain the environment and human health. The dredged sludge (DS) and water hyacinth (WH) generated from dredging projects are potential environmental threats, and therefore suitable methods need to be [...] Read more.

Carrying out research on the management of electrolytic manganese residue (EMR) is necessary to maintain the environment and human health. The dredged sludge (DS) and water hyacinth (WH) generated from dredging projects are potential environmental threats, and therefore suitable methods need to be found for their treatment. In this study, ceramsite was prepared by a two-step low-temperature firing method using DS and EMR as raw materials, WH as a pore-forming additive, and aluminate cement as a binder for the adsorption of phosphorus from wastewater. The optimal ratio and process parameters of the ceramsite were determined by mechanical and adsorption properties. The static adsorption experiments were conducted to study the effect of ceramsite dosage and solution pH on the removal of phosphorus. At the same time, dynamic adsorption experiments were designed to consider the influence of flow rate on its actual absorption effect, to explore the actual effect of ceramsite in wastewater treatment, and to derive a dynamic adsorption model that can provide technical support and theoretical guidance for environmental management. Full article

(This article belongs to the Special Issue Environmentally Friendly Adsorption Materials)

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18 pages, 3261 KiB

Open AccessArticle

Recovery of Cerium Salts from Sewage Sludge Resulting from the Coagulation of Brewery Wastewater with Recycled Cerium Coagulant

by Paweł Lejwoda, Barbara Białecka, Krzysztof Barbusiński and Maciej Thomas

Materials 2024, 17(4), 938; https://doi.org/10.3390/ma17040938 - 17 Feb 2024

Cited by 1 | Viewed by 1069

Abstract

Due to the high cost and limited sources of cerium coagulants, it is extremely important to take measures to recycle this raw material. This paper presents the new possibility of recovering cerium(III) chloride, cerium(III) sulphate, cerium(IV) sulphate, and potentially phosphate from sewage sludge [...] Read more.

Due to the high cost and limited sources of cerium coagulants, it is extremely important to take measures to recycle this raw material. This paper presents the new possibility of recovering cerium(III) chloride, cerium(III) sulphate, cerium(IV) sulphate, and potentially phosphate from sewage sludge (101.5 g/kg Ce and 22.2 g/kg total P) through a brewery wastewater treatment process using recycled CeCl₃ as a coagulant. In order to recover the Ce and P, the sludge was subjected to extraction using an HCl solution. Optimal process conditions were determined by means of central composite design and response surface methodology (CCD/RSM) for three input parameters (HCl mass, reaction time, and extractant volume). Under optimal conditions (0.35 g HCl per 1 g of sludge, 40 min reaction time, extractant volume of 25 mL per 1 g of sludge), the highest efficiency obtained was 99.6% and 97.5% for Ce and P, respectively. Cerium(III) oxalate as Ce₂(C₂O₄)₃∙10H₂O was precipitated from the obtained solution using H₂C₂O₄ (99.97%) and decomposed into CeO₂ (at 350 °C), which was afterwards subjected to a reaction with HCl (30%, m/m) and H₂O₂ (30%, m/m), which led to the crystallisation of CeCl₃∙7H₂O with a purity of 98.6% and a yield of 97.0%. The obtained CeO₂ was also subjected to a reaction with H₂SO₄ (96%, m/m) and H₂O₂ (30%, m/m), which produced Ce₂(SO₄)₃ with a yield of 97.4%. The CeO₂ was also subjected to a reaction with only H₂SO₄ (96%, m/m), which produced Ce(SO₄)₂ with a yield of 98.3%. The filtrate obtained after filtering the Ce₂(C₂O₄)₃∙10H₂O contained 570 mg/L of P, which enabled its use as a source of phosphorus compounds. The presented processes of Ce and potentially P recovery from sewage sludge originating from brewery wastewater contribute to the idea of a circular economy. Full article

(This article belongs to the Special Issue Recovery and Preparation of Innovative Products and Composite Materials for Environmental Applications)

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22 pages, 10268 KiB

Open AccessArticle

Investigation of the Structure-Forming Potential of Protein Components in the Reformulation of the Composition of Edible Films

by Monika Janowicz, Sabina Galus, Karolina Szulc, Agnieszka Ciurzyńska and Małgorzata Nowacka

Materials 2024, 17(4), 937; https://doi.org/10.3390/ma17040937 - 17 Feb 2024

Cited by 3 | Viewed by 1096

Abstract

To optimize the functional properties of edible films or coatings, mixtures of several ingredients are used, including food processing by-products. In this way, pectin from fruit pomace, whey proteins from whey as a by-product of rennet cheese production, and gelatin from by-products of [...] Read more.

To optimize the functional properties of edible films or coatings, mixtures of several ingredients are used, including food processing by-products. In this way, pectin from fruit pomace, whey proteins from whey as a by-product of rennet cheese production, and gelatin from by-products of the processing of slaughtered animals can be obtained. The aim and scope of the investigation were to verify the hypothesis of the research, which assumes that the addition of beef broth to edible gelatin films will affect the gelation processes of the tested film-forming solutions and will allow for the modification of the edible properties of the films obtained based on these solutions. Measurements were carried out to determine the visual parameters, mechanical strengths, surface and cross-sectional structures, FTIR spectra, thermal degradation rates, and hydrophilicities of the prepared gelatin films. The water content, water vapor permeability, and course of water vapor sorption isotherms of the films were also examined, as well as the course of the gelation process for film-forming solutions. The addition of broth to film-forming solutions was found to increase their opacity and color saturation, especially for the ones that were yellow. The films with the addition of broth were more uneven on the surface and more resistant to stretching, and in the case of the selected types of gelatins, they also formed a more stable gel. The broth increased the hydrophilicity and permeability of the water vapor and reduced the water content of the films. The addition of broth enables the practical use of edible films, but it is necessary to modify some features. Full article

(This article belongs to the Special Issue Bioactive Materials for Additive Manufacturing)

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