Gels | Special Issue : Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition)

Research

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23 pages, 16247 KiB

Open AccessArticle

Sol–Gel Derived Alumina Particles for the Reinforcement of Copper Films on Brass Substrates

by Samah Sasi Maoloud Mohamed, Marija M. Vuksanović, Dana G. Vasiljević-Radović, Ljiljana Janković Mandić, Radmila M. Jančić Heinneman, Aleksandar D. Marinković and Ivana O. Mladenović

Gels 2024, 10(10), 648; https://doi.org/10.3390/gels10100648 - 11 Oct 2024

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Abstract

The aim of this study is to provide tailored alumina particles suitable for reinforcing the metal matrix film. The sol–gel method was chosen to prepare particles of submicron size and to control crystal structure by calcination. In this study, copper-based metal matrix composite [...] Read more.

The aim of this study is to provide tailored alumina particles suitable for reinforcing the metal matrix film. The sol–gel method was chosen to prepare particles of submicron size and to control crystal structure by calcination. In this study, copper-based metal matrix composite (MMC) films are developed on brass substrates with different electrodeposition times and alumina concentrations. Scanning electron microscopy (FE-SEM) with energy-dispersive spectroscopy (EDS), TEM, and X-ray diffraction (XRD) were used to characterize the reinforcing phase. The MMC Cu-Al₂O₃ films were synthesized electrochemically using the co-electrodeposition method. Microstructural and topographical analyses of pure (alumina-free) Cu films and the Cu films with incorporated Al₂O₃ particles were performed using FE-SEM/EDS and AFM, respectively. Hardness and adhesion resistance were investigated using the Vickers microindentation test and evaluated by applying the Chen–Gao (C-G) mathematical model. The sessile drop method was used for measuring contact angles for water. The microhardness and adhesion of the MMC Cu-Al₂O₃ films are improved when Al₂O₃ is added. The concentration of alumina particles in the electrolyte correlates with an increase in absolute film hardness in the way that 1.0 wt.% of alumina in electrolytes results in a 9.96% increase compared to the pure copper film, and the improvement is maximal in the film obtained from electrolytes containing 3.0 wt.% alumina giving the film 2.128 GPa, a 134% hardness value of that of the pure copper film. The surface roughness of the MMC film increased from 2.8 to 6.9 times compared to the Cu film without particles. The decrease in the water contact angle of Cu films with incorporated alumina particles relative to the pure Cu films was from 84.94° to 58.78°. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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17 pages, 5480 KiB

Open AccessArticle

Development of Environmentally Friendly and Economical Flood-Prevention Stones Based on the Sediments of the Yellow River

by Ying Liu, Hao Xiao, Yongxiang Jia, Yajun Lv, Li Dai and Chen Yang

Gels 2024, 10(10), 622; https://doi.org/10.3390/gels10100622 - 27 Sep 2024

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Abstract

The deposition of Yellow River sediment in the middle and lower reaches is a significant factor in the siltation of reservoirs and the occurrence of serious flooding along the river. The efficient and valuable utilization of Yellow River sediment has already become a [...] Read more.

The deposition of Yellow River sediment in the middle and lower reaches is a significant factor in the siltation of reservoirs and the occurrence of serious flooding along the river. The efficient and valuable utilization of Yellow River sediment has already become a key research topic in this field. In this study, we have employed Yellow River sediment as the primary material, in conjunction with commercially available slag, fly ash, and quicklime as the binder, to develop a novel type of artificial flood-prevention stone. Following a 28-day standard curing procedure, the highest compressive strength of the prepared artificial stone was recorded at 4.29 MPa, with a value exceeding 0.7 MPa under wet conditions. The results demonstrated that the prepared artificial stone met the specifications for artificial flood-prevention stones. The curing mechanism, as evidenced by analyses from SEM and XRD testing, indicated that the alkali excitation process in the binder, which produced C-A-S-H gel, was the key factor in enhancing the compressive strength of the specimens. Notably, an evaluation of the amount of CO₂ emissions and the cost of the artificial stone concluded that the preparation process was both environmentally friendly and cost-effective. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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15 pages, 5039 KiB

Open AccessArticle

Eco-Friendly Sol–Gel Coatings with Organic Corrosion Inhibitors for Lightweight AZ61 Alloy

by Jorge Domínguez-Martínez, Jesús López-Sánchez, Federico García-Galván, Aída Serrano, Violeta Barranco, Juan Carlos Galván, Óscar Rodríguez de la Fuente and Noemí Carmona

Gels 2024, 10(3), 168; https://doi.org/10.3390/gels10030168 - 27 Feb 2024

Viewed by 1619

Abstract

The latest advances in technology and materials science have catalyzed a transformative shift towards the adoption of environmentally conscious and lightweight materials across key sectors such as aeronautics, biomedical, and automotive industries. Noteworthy among these innovations are the magnesium-aluminum (Mg-Al) alloys employed in [...] Read more.

The latest advances in technology and materials science have catalyzed a transformative shift towards the adoption of environmentally conscious and lightweight materials across key sectors such as aeronautics, biomedical, and automotive industries. Noteworthy among these innovations are the magnesium-aluminum (Mg-Al) alloys employed in aeronautical applications, contributing to the overall reduction in aircraft weight and subsequently diminishing fuel consumption and mitigating atmospheric emissions. The present work delves into a study of the anti-corrosive properties inherent in various sol-gel coatings, leveraging a range of environmentally friendly corrosion inhibitors, specifically tailored for samples of the AZ61 alloy. Methodologically, the work involves the synthesis and application of sol-gel coatings on AZ61 alloy containing eco-friendly inhibitors: L-cysteine, N-acetyl-cysteine, curcumin and methylene blue. Subsequently, an accelerated corrosion test in a simulated saline environment is performed. Through microstructural and compositional analyses, the best inhibitors responses are achieved with inhibitors containing S, N heteroatoms and conjugated double bonds in their structure, probably due to the creation of a continuous MgCl₂ layer. This research contributes to the ongoing discourse on protective eco-coatings, aligning with the broader paradigm shift towards sustainable and lightweight materials in key industries. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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14 pages, 3589 KiB

Open AccessArticle

Combustion Enhancement of Gel Propellant Containing High Concentration Aluminum Particles Based on Carbon Synergistic Effect

by Jiyuan Chen, Hui Zhao, Weifeng Li and Haifeng Liu

Gels 2024, 10(2), 89; https://doi.org/10.3390/gels10020089 - 24 Jan 2024

Viewed by 1604

Abstract

The addition of aluminum particles to gel propellants can improve combustion performance. However, the agglomeration of aluminum during the combustion process can result in a series of negative effects. In this paper, the aluminum agglomeration inhibition method of gel propellant based on carbon [...] Read more.

The addition of aluminum particles to gel propellants can improve combustion performance. However, the agglomeration of aluminum during the combustion process can result in a series of negative effects. In this paper, the aluminum agglomeration inhibition method of gel propellant based on carbon synergistic effect is proposed. Carbon particles exhibit excellent combustion properties, and the gaseous product CO₂ generated during combustion can mitigate the agglomeration of aluminum. The research demonstrates that incorporating carbon particles into aluminum-containing gel effectively reduces the incomplete combustion of aluminum particles and increases the volumetric calorific value of the gel. When the mass fraction of carbon is 5 wt%, the volume calorific value of the gel reaches the highest. Meanwhile, the rheological experiments show that the addition of carbon particles can improve the shear-thinning properties of the gel, which is beneficial to the atomization and combustion processes of the gel. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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18 pages, 7133 KiB

Open AccessArticle

Acoustic Fractional Propagation in Terms of Porous Xerogel and Fractal Parameters

by Maria-Alexandra Paun, Vladimir-Alexandru Paun and Viorel-Puiu Paun

Gels 2024, 10(1), 83; https://doi.org/10.3390/gels10010083 - 22 Jan 2024

Cited by 2 | Viewed by 1430

Abstract

This article portrays solid xerogel-type materials, based on chitosan, TEGylated phenothiazine, and TEG (tri-ethylene glycol), dotted with a large number of pores, that are effectively represented in their constitutive structure. They were assumed to be fractal geometrical entities and adjudged as such. The [...] Read more.

This article portrays solid xerogel-type materials, based on chitosan, TEGylated phenothiazine, and TEG (tri-ethylene glycol), dotted with a large number of pores, that are effectively represented in their constitutive structure. They were assumed to be fractal geometrical entities and adjudged as such. The acoustic fractional propagation equation in a fractal porous media was successfully applied and solved with the help of Bessel functions. In addition, the fractal character was demonstrated by the produced fractal analysis, and it has been proven on the evaluated scanning electron microscopy (SEM) pictures of porous xerogel compounds. The fractal parameters (more precisely, the fractal dimension), the lacunarity, and the Hurst index were calculated with great accuracy. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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14 pages, 2917 KiB

Open AccessArticle

Electrochemical Storage Behavior of a High-Capacity Mg-Doped P2-Type Na_2/3Fe_1−yMn_yO₂ Cathode Material Synthesized by a Sol–Gel Method

by Mobinul Islam, Md. Shahriar Ahmed, Daseul Han, Gazi A. K. M. Rafiqul Bari and Kyung-Wan Nam

Gels 2024, 10(1), 24; https://doi.org/10.3390/gels10010024 - 27 Dec 2023

Cited by 2 | Viewed by 2052

Abstract

Grid-scale energy storage applications can benefit from rechargeable sodium-ion batteries. As a potential material for making non-cobalt, nickel-free, cost-effective cathodes, earth-abundant Na_2/3Fe_1/2Mn_1/2O₂ is of particular interest. However, Mn³⁺ ions are particularly susceptible to the Jahn–Teller [...] Read more.

Grid-scale energy storage applications can benefit from rechargeable sodium-ion batteries. As a potential material for making non-cobalt, nickel-free, cost-effective cathodes, earth-abundant Na_2/3Fe_1/2Mn_1/2O₂ is of particular interest. However, Mn³⁺ ions are particularly susceptible to the Jahn–Teller effect, which can lead to an unstable structure and continuous capacity degradation. Modifying the crystal structure by aliovalent doping is considered an effective strategy to alleviate the Jahn–Teller effect. Using a sol–gel synthesis route followed by heat treatment, we succeeded in preparing an Mg-doped Na_2/3Fe_1−yMn_yO₂ cathode. Its electrochemical properties and charge compensation mechanism were then studied using synchrotron-based X-ray absorption spectroscopy and in situ X-ray diffraction techniques. The results revealed that Mg doping reduced the number of Mn³⁺ Jahn–Teller centers and alleviated high voltage phase transition. However, Mg doping was unable to suppress the P2-P’2 phase transition at a low voltage discharge. An initial discharge capacity of about 196 mAh g⁻¹ was obtained at a current density of 20 mAh g⁻¹, and 60% of rate capability was maintained at a current density of 200 mAh g⁻¹ in a voltage range of 1.5–4.3 V. This study will greatly contribute to the ongoing search for advanced and efficient cathodes from earth-abundant elements for rechargeable sodium-ion batteries operable at room temperature. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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18 pages, 3265 KiB

Open AccessArticle

Synthesis of Highly Luminescent Silica-Coated Upconversion Nanoparticles from Lanthanide Oxides or Nitrates Using Co-Precipitation and Sol–Gel Methods

by Ana Iglesias-Mejuto, Alyne Lamy-Mendes, João Pina, Benilde F. O. Costa, Carlos A. García-González and Luisa Durães

Gels 2024, 10(1), 13; https://doi.org/10.3390/gels10010013 - 22 Dec 2023

Cited by 3 | Viewed by 1803

Abstract

Upconversion nanoparticles (UCNPs) are under consideration for their use as bioimaging probes with enhanced optical performance for real time follow-up under non-invasive conditions. Photostable and core-shell NaYF₄:Yb³⁺, Er³⁺-SiO₂ UCNPs obtained by a novel and simple co-precipitation [...] Read more.

Upconversion nanoparticles (UCNPs) are under consideration for their use as bioimaging probes with enhanced optical performance for real time follow-up under non-invasive conditions. Photostable and core-shell NaYF₄:Yb³⁺, Er³⁺-SiO₂ UCNPs obtained by a novel and simple co-precipitation method from lanthanide nitrates or oxides were herein synthesized for the first time. The sol–gel Stöber method followed by oven or supercritical gel drying was used to confer biocompatible surface properties to UCNPs by the formation of an ultrathin silica coating. Upconversion (UC) spectra were studied to evaluate the fluorescence of UCNPs upon red/near infrared (NIR) irradiation. ζ-potential measurements, TEM analyses, XRD patterns and long-term physicochemical stability were also assessed and confirmed that the UCNPs co-precipitation synthesis is a shape- and phase-controlling approach. The bio- and hemocompatibility of the UCNPs formulation with the highest fluorescence intensity was evaluated with murine fibroblasts and human blood, respectively, and provided excellent results that endorse the efficacy of the silica gel coating. The herein synthesized UCNPs can be regarded as efficient fluorescent probes for bioimaging purposes with the high luminescence, physicochemical stability and biocompatibility required for biomedical applications. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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13 pages, 5942 KiB

Open AccessArticle

A SEM-EDX Study on the Structure of Phenyl Phosphinic Hybrids Containing Boron and Zirconium

by Petru Merghes, Narcis Varan, Gheorghe Ilia, Iosif Hulka and Vasile Simulescu

Gels 2023, 9(9), 706; https://doi.org/10.3390/gels9090706 - 1 Sep 2023

Viewed by 1177

Abstract

The SEM-EDX method was used to investigate the structure and morphology of organic–inorganic hybrids containing zirconium, boron and phosphorus compounds, synthesized by the sol–gel method. We started by using, for the first time together, zirconyl chloride hexa-hydrate (ZrOCl₂·6H₂O), phenyl [...] Read more.

The SEM-EDX method was used to investigate the structure and morphology of organic–inorganic hybrids containing zirconium, boron and phosphorus compounds, synthesized by the sol–gel method. We started by using, for the first time together, zirconyl chloride hexa-hydrate (ZrOCl₂·6H₂O), phenyl phosphinic acid and triethyl borate as precursors and reagents, at different molar ratios. The obtained hybrids showed a very high thermal stability and are not soluble in water or in organic solvents. As a consequence, such hybrid solid materials are suitable for applications at high temperatures. The obtained hybrids have complex 3D structures and form organic–inorganic networks containing Zr-O-Zr, Zr-O-P and Zr-O-B bridges. Such organic–inorganic networks are also expected to form supramolecular structures and to have many potential applications in different fields of great interest such as catalysis, medicine, agriculture, energy storage, fuel cells, sensors, electrochemical devices and supramolecular chemistry. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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12 pages, 2289 KiB

Open AccessArticle

Layered Sol–Gel Deposition of a Sn, Ti, Zn, and Pr Mixed Oxide Thin Film with Electrical Properties for Gas Sensing

by Izabella Dascalu, Cristian Hornoiu, Jose Maria Calderon Moreno, Petre Osiceanu and Simona Somacescu

Gels 2023, 9(8), 638; https://doi.org/10.3390/gels9080638 - 8 Aug 2023

Cited by 1 | Viewed by 1118

Abstract

This article presents a layered mixed oxide thin film composed of Sn, Ti, Zn, and Pr obtained by sol–gel deposition for gas sensing applications. The film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-Vis spectroscopy, Scanning electron microscopy [...] Read more.

This article presents a layered mixed oxide thin film composed of Sn, Ti, Zn, and Pr obtained by sol–gel deposition for gas sensing applications. The film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-Vis spectroscopy, Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and Electrochemical impedance spectroscopy (EIS). X-ray diffraction results showed the presence of a single crystalline phase with a cassiterite-like structure. Raman spectroscopy revealed characteristic bands of oxygen-deficient SnO₂-based nanocrystallites. The band gap energy calculated from UV-Vis spectroscopy is Eg = 3.83 eV. The XPS proved the presence on the surface of all elements introduced by the inorganic precursors as well as their oxidation states. Thus, Sn⁴⁺, Ti⁴⁺, Zn²⁺, and Pr³⁺ were detected on the surface. Moreover, by XPS, we highlighted the presence of OH groups and water adsorbed on the surface. SEM showed the five-layer morphology of the film after five successive depositions. Electrochemical properties were determined by EIS-impedance spectroscopy. The selectivity for gas sensing was also investigated for methane, propane, and formaldehyde and the gas sensing mechanism was explained. The results indicated that the mixed oxide thin film exhibited high sensitivity and selectivity towards specific gases. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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19 pages, 20330 KiB

Open AccessArticle

Fractal Analysis of Four Xerogels Based on TEGylated Phenothiazine and Chitosan

by Maria-Alexandra Paun, Mihai-Virgil Nichita, Vladimir-Alexandru Paun and Viorel-Puiu Paun

Gels 2023, 9(6), 435; https://doi.org/10.3390/gels9060435 - 25 May 2023

Cited by 1 | Viewed by 1231

Abstract

The present article describes novel massive materials (in the solid phase) based on TEGylated phenothiazine and chitosan that possess great capability to recover mercury ions from constituent aqueous solutions. These were produced by chitosan hydrogelation accompanied by formyl subsidiary item of TEGylated phenothiazine, [...] Read more.

The present article describes novel massive materials (in the solid phase) based on TEGylated phenothiazine and chitosan that possess great capability to recover mercury ions from constituent aqueous solutions. These were produced by chitosan hydrogelation accompanied by formyl subsidiary item of TEGylated phenothiazine, attended by lyophilization. The delineation and structure description of the obtained material or supramolecular assembly were realized by FTIR (Fourier transform infrared) spectroscopy, X-ray diffraction, and POM (Polarized Light Optical Microscopy). The morphology of their texture was kept under observation by SEM (Scanning Electron Microscopy). The obtained SEM images were evaluated by fractal analysis. The fractal parameters of interest were calculated, including the fractal dimension and lacunarity. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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15 pages, 20887 KiB

Open AccessArticle

Chemiresistors with In₂O₃ Nanostructured Sensitive Films Used for Ozone Detection at Room Temperature

by Mariana Chelu, Paul Chesler, Cristian Hornoiu, Mihai Anastasescu, Jose Maria Calderon-Moreno, Daiana Mitrea, Costin Brasoveanu, Carmen Moldovan and Mariuca Gartner

Gels 2023, 9(5), 355; https://doi.org/10.3390/gels9050355 - 23 Apr 2023

Cited by 1 | Viewed by 2018

Abstract

Detection of greenhouse gases is essential because harmful gases in the air diffuse rapidly over large areas in a short period of time, causing air pollution that will induce climate change with catastrophic consequences over time. Among the materials with favorable morphologies for [...] Read more.

Detection of greenhouse gases is essential because harmful gases in the air diffuse rapidly over large areas in a short period of time, causing air pollution that will induce climate change with catastrophic consequences over time. Among the materials with favorable morphologies for gas detection (nanofibers, nanorods, nanosheets), large specific surfaces, high sensitivity and low production costs, we chose nanostructured porous films of In₂O₃ obtained by the sol-gel method, deposited on alumina transducers, with gold (Au) interdigitated electrodes (IDE) and platinum (Pt) heating circuits. Sensitive films contained 10 deposited layers, involving intermediate and final thermal treatments to stabilize the sensitive film. The fabricated sensor was characterized using AFM, SEM, EDX and XRD. The film morphology is complex, containing fibrillar formations and some quasi-spherical conglomerates. The deposited sensitive films are rough, thus favoring gas adsorption. Ozone sensing tests were performed at different temperatures. The highest response of the ozone sensor was recorded at room temperature, considered to be the working temperature for this specific sensor. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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12 pages, 5081 KiB

Open AccessArticle

Evaluation of Low-Toxic Hybrid Sol-Gel Coatings with Organic pH-Sensitive Inhibitors for Corrosion Protection of AA2024 Aluminium Alloy

by Eva Jaldo Serrano, Jesús López-Sánchez, Federico García-Galván, Aida Serrano, Óscar Rodríguez de la Fuente, Violeta Barranco, Juan Carlos Galván and Noemí Carmona

Gels 2023, 9(4), 294; https://doi.org/10.3390/gels9040294 - 2 Apr 2023

Cited by 3 | Viewed by 2066

Abstract

Today’s environmental needs require the reduction of the weight of vehicles, thus reducing fuel consumption and associated emissions. For this reason, the use of light alloys is being studied, which, due to their reactivity, must be protected before use. In this work, the [...] Read more.

Today’s environmental needs require the reduction of the weight of vehicles, thus reducing fuel consumption and associated emissions. For this reason, the use of light alloys is being studied, which, due to their reactivity, must be protected before use. In this work, the effectiveness of a hybrid sol-gel coating doped with various organic environmentally friendly corrosion inhibitors applied to an AA2024 lightweight aluminium alloy is evaluated. Some of the inhibitors tested are pH indicators, acting as both corrosion inhibitors and optical sensors for the surface of the alloy. Samples are subjected to a corrosion test in a simulated saline environment and characterised before and after the test. The experimental results regarding their best inhibitor performance for their potential application in the transport industry are evaluated. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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10 pages, 2823 KiB

Open AccessCommunication

Study of the Possibility of Using Sol–Gel Technology to Obtain Magnetic Nanoparticles Based on Transition Metal Ferrites

by Nina Shabelskaya, Sergey Sulima, Elena Sulima, Oleg Medennikov, Marina Kulikova, Tatyana Kolesnikova and Svetlana Sushkova

Gels 2023, 9(3), 217; https://doi.org/10.3390/gels9030217 - 14 Mar 2023

Cited by 4 | Viewed by 1478

Abstract

The article presents results for the magnetic nanoparticles sol–gel method synthesis of cobalt (II) ferrite and organic–inorganic composite materials based on it. The obtained materials were characterized using X-ray phase analysis, scanning and transmission electron microscopy, Scherrer, Brunauer–Emmett–Teller (BET) methods. A composite materials [...] Read more.

The article presents results for the magnetic nanoparticles sol–gel method synthesis of cobalt (II) ferrite and organic–inorganic composite materials based on it. The obtained materials were characterized using X-ray phase analysis, scanning and transmission electron microscopy, Scherrer, Brunauer–Emmett–Teller (BET) methods. A composite materials formation mechanism is proposed, which includes a gelation stage where transition element cation chelate complexes react with citric acid and subsequently decompose under heating. The fundamental possibility of obtaining an organo–inorganic composite material based on cobalt (II) ferrite and an organic carrier using the presented method has been proved. Composite materials formation is established to lead to a significant (5–9 times) increase in the sample surface area. Materials with a developed surface are formed: the surface area measured by the BET method is 83–143 m²/g. The resulting composite materials have sufficient magnetic properties to be mobile in a magnetic field. Consequently, wide possibilities for polyfunctional materials synthesis open up for various applications in medicine. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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Review

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18 pages, 2899 KiB

Open AccessReview

Green and Low-Cost Modified Pisha Sandstone Geopolymer Gel Materials for Ecological Restoration: A Phase Review

by Changming Li, Yubing Fu, Haifeng Cheng, Yaozong Wang, Dongyang Jia and Hui Liu

Gels 2024, 10(5), 302; https://doi.org/10.3390/gels10050302 - 29 Apr 2024

Cited by 2 | Viewed by 1657

Abstract

Pisha sandstone (PS) is a special interbedded rock in the middle reaches of the Yellow River that experiences severe weathering and is loose and broken. Due to severe multiple erosion events, the Pisha sandstone region is called “the most severe water loss and [...] Read more.

Pisha sandstone (PS) is a special interbedded rock in the middle reaches of the Yellow River that experiences severe weathering and is loose and broken. Due to severe multiple erosion events, the Pisha sandstone region is called “the most severe water loss and soil erosion in the world” and “the ecological cancer of the earth”. As a special pozzolanic mineral, PS has the potential to be used as precursors for the synthesis of green and low-carbon geopolymer gel materials and applied in ecological restoration. This paper aims to undertake a phase review of the precursors for geopolymer gel materials. The genesis and distribution, physical and chemical characterization, erosion characteristics, and advances in the ecological restoration of PS are all summarized. Furthermore, current advances in the use of PS for the synthesis of geopolymer gel materials in terms of mechanical properties and durability are discussed. The production of Pisha sandstone geopolymer gels through the binder jetting technique and 3D printing techniques is prospected. Meanwhile, the prospects for the resource application of PS in mine rehabilitation and sustainable ecology are discussed. In the future, multifactor-driven comprehensive measures should be further investigated in order to achieve ecological restoration of the Pisha sandstone region and promote high-quality development of the Yellow River Basin. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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37 pages, 9425 KiB

Open AccessReview

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

by Farqad Yousuf Al-saffar, Leong Sing Wong and Suvash Chandra Paul

Gels 2023, 9(8), 613; https://doi.org/10.3390/gels9080613 - 28 Jul 2023

Cited by 13 | Viewed by 2643

Abstract

Concrete as a building material is susceptible to degradation by environmental threats such as thermal diffusion, acid and sulphate infiltration, and chloride penetration. Hence, the inclusion of nanomaterials in concrete has a positive effect in terms of promoting its mechanical strength and durability [...] Read more.

Concrete as a building material is susceptible to degradation by environmental threats such as thermal diffusion, acid and sulphate infiltration, and chloride penetration. Hence, the inclusion of nanomaterials in concrete has a positive effect in terms of promoting its mechanical strength and durability performance, as well as resulting in energy savings due to reduced cement consumption in concrete production. This review article discussed the novel advances in research regarding C-S-H gel promotion and concrete durability improvement using nanomaterials. Basically, this review deals with topics relevant to the influence of nanomaterials on concrete’s resistance to heat, acid, sulphate, chlorides, and wear deterioration, as well as the impact on concrete microstructure and chemical bonding. The significance of this review is a critical discussion on the cementation mechanism of nanoparticles in enhancing durability properties owing to their nanofiller effect, pozzolanic reactivity, and nucleation effect. The utilization of nanoparticles enhanced the hydrolysis of cement, leading to a rise in the production of C-S-H gel. Consequently, this improvement in concrete microstructure led to a reduction in the number of capillary pores and pore connectivity, thereby improving the concrete’s water resistance. Microstructural and chemical evidence obtained using SEM and XRD indicated that nanomaterials facilitated the formation of cement gel either by reacting pozzolanically with portlandite to generate more C-S-H gel or by functioning as nucleation sites. Due to an increased rate of C-S-H gel formation, concrete enhanced with nanoparticles exhibited greater durability against heat damage, external attack by acids and sulphates, chloride diffusion, and surface abrasion. The durability improvement following nanomaterial incorporation into concrete can be summarised as enhanced residual mechanical strength, reduced concrete mass loss, reduced diffusion coefficients for thermal and chloride, improved performance against sulphates and acid attack, and increased surface resistance to abrasion. Full article

(This article belongs to the Special Issue Gels: Synthesis, Characterization and Applications in High Performance Chemistry (2nd Edition))

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