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Gels
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Advances in Xerogels: From Design to Applications (2nd Edition)
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Advances in Xerogels: From Design to Applications (2nd Edition)

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Processing and Engineering".

Deadline for manuscript submissions: 30 September 2024 | Viewed by 11704

Special Issue Editors

Dr. Francesco Caridi

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Guest Editor
Department of Mathematics and Informatics, Physic and Earth Sciences (MIFT), University of Messina, 98166 Messina, Italy
Interests: environmental radioactivity; gamma spectrometry; liquid scintillation; alpha spectrometry; gas radon detection; emanometry; ionizing radiations
Special Issues, Collections and Topics in MDPI journals
Dr. Giuseppe Paladini

E-Mail Website
Guest Editor
Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, 98166 Messina, Italy
Interests: biopolymers; xerogels; nanocellulose; drug delivery systems; FTIR-ATR spectroscopy; Raman spectroscopy; neutron spectroscopy; material characterization
Special Issues, Collections and Topics in MDPI journals
Dr. Andrea Fiorati

E-Mail Website
Guest Editor
Department of Chemistry, Materials, and Chemical Engineering, “G. Natta”, Politecnico di Milano, 20133 Milan, Italy
Interests: nanocellulose; biomaterials; materials characterization; chemical-physical approaches; nanostructured and composite materials; hydrogels; mass transfer phenomena; food packaging
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are grateful to all authors, reviewers and readers for their responses to the first volume of our Special Issue on “Advances in Xerogels: From Design to Applications”. You can access these articles for free via the link:

Advances in Xerogels: From Design to Applications (1st Edition)

The design of novel xerogels for several applications has become a hot topic in the field of material science and engineering. Since their structures and morphologies can be conveniently controlled during the synthesis process, the development of xerogels has gained interest within the scientific community.

Based on these considerations, this Special Issue of Gels aims to collect high-quality papers on the latest breakthroughs and advances in the field of the xerogels science from design to application. In particular, we encourage submissions focused on both well-established and/or non-conventional methods for the synthesis and characterization of xerogels. The goal is to obtain insights into fundamental and applied aspects related to organic/inorganic xerogel-like materials. Cutting-edge studies, both theoretical and experimental ones, focused on the structural, chemical, rheological and dynamical properties of xerogels and xerogel-based derivatives are welcome.

As Guest Editors, we would like to invite you to contribute a research paper or a review on any topic related to this area.

Prof. Dr. Francesco Caridi
Dr. Giuseppe Paladini
Dr. Andrea Fiorati
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Gels is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • xerogels synthesis
  • xerogels fundamentals
  • xerogels properties
  • xerogels applications
  • physical-/chemical features of xerogels
  • xerogels structural property correlations
  • xerogels dynamical property correlations

Published Papers (9 papers)

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Research

14 pages, 2771 KiB  
Article
Improving the Decay Resistance of Wood through the Fixation of Different Nanoparticles Using Silica Aerogel
by Miklós Bak, Zsófia Plesér and Róbert Németh
Gels 2024, 10(4), 255; https://0-doi-org.brum.beds.ac.uk/10.3390/gels10040255 - 10 Apr 2024
Viewed by 592
Abstract
Nowadays, the protection of wood is becoming more important with the increasing demand for durable wood, in addition to its limited accessibility. One possible way to increase the durability is the use of nanoparticles, which can be effective even with a low intake [...] Read more.
Nowadays, the protection of wood is becoming more important with the increasing demand for durable wood, in addition to its limited accessibility. One possible way to increase the durability is the use of nanoparticles, which can be effective even with a low intake of active ingredients. However, avoiding their leaching is a challenge. A possible solution to leaching is the use of silica aerogel as a fixative. This study investigated the use of mesoporous silica aerogel against the leaching of different nanoparticles under laboratory conditions. Tests were performed involving beech (Fagus sylvatica) and Scots pine (Pinus sylvestris) sapwood, using Trametes versicolor as a white rot and Coniophora puteana as a brown rot fungus. The results show that the subsequent treatment of the wood with mesoporous silica aerogel effectively fixed the nanoparticles in wood. The durability of the samples without aerogel significantly decreased as a result of leaching, whereas the resistance of the samples treated with aerogel decreased only slightly. However, the silica aerogel modification itself caused the leaching of silver nanoparticles, which is a limitation in the use of this method for the fixation of nanoparticles. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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11 pages, 2116 KiB  
Article
Synthesis of Ni-Doped Graphene Aerogels for Electrochemical Applications
by Marina González-Barriuso, Mario Sánchez-Suárez, Judith González-Lavín, Ana Arenillas and Natalia Rey-Raap
Gels 2024, 10(3), 180; https://0-doi-org.brum.beds.ac.uk/10.3390/gels10030180 - 04 Mar 2024
Viewed by 1162
Abstract
Carbonaceous materials used in most electrochemical applications require high specific surface area, adequate pore size distribution, and high electrical conductivity to ensure good interaction with the electrolyte and fast electron transport. The development of transition metal doped graphene aerogels is a possible solution, [...] Read more.
Carbonaceous materials used in most electrochemical applications require high specific surface area, adequate pore size distribution, and high electrical conductivity to ensure good interaction with the electrolyte and fast electron transport. The development of transition metal doped graphene aerogels is a possible solution, since their structure, morphology, and electrical properties can be controlled during the synthesis process. This work aims to synthesize Ni-doped graphene aerogels to study the role of different nickel salts in the sol-gel reaction and their final properties. The characterization data show that, regardless of the nature of the Ni salts, the surface area, volume of micropores, and enveloped density decrease, while the porosity and electrical conductivity increase. However, differences in morphology, mesopore size distribution, degree of order of the carbon structure, and electrical conductivity were observed depending on the type of Ni salt. It was found that nickel nitrate results in a material with a broader mesopore distribution, higher electrical conductivity, and hence, higher electrochemical surface area, demonstrating that graphene aerogels can be easily synthesized with tailored properties to fit the requirements of specific electrochemical applications. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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16 pages, 3398 KiB  
Article
Design of Nickel-Containing Nanocomposites Based on Ordered Mesoporous Silica: Synthesis, Structure, and Methylene Blue Adsorption
by Tatyana Kouznetsova, Andrei Ivanets, Vladimir Prozorovich, Polina Shornikova, Lizaveta Kapysh, Qiang Tian, László Péter, László Trif and László Almásy
Gels 2024, 10(2), 133; https://0-doi-org.brum.beds.ac.uk/10.3390/gels10020133 - 06 Feb 2024
Viewed by 1134
Abstract
Mesoporous materials containing heteroelements have a huge potential for use as catalysts, exchangers, and adsorbents due to their tunable nanometer-sized pores and exceptionally large internal surfaces accessible to bulky organic molecules. In the present work, ordered mesoporous silica containing Ni atoms as active [...] Read more.
Mesoporous materials containing heteroelements have a huge potential for use as catalysts, exchangers, and adsorbents due to their tunable nanometer-sized pores and exceptionally large internal surfaces accessible to bulky organic molecules. In the present work, ordered mesoporous silica containing Ni atoms as active sites was synthesized by a new low-temperature method of condensation of silica precursors on a micellar template from aqueous solutions in the presence of nickel salt. The homogeneity of the resulting product was achieved by introducing ammonia and ammonium salt as a buffer to maintain a constant pH value. The obtained materials were characterized by nitrogen sorption, X-ray and neutron diffraction, scanning electron microscopy, infrared spectroscopy, and thermal analysis. Their morphology consists of polydisperse spherical particles 50–300 nm in size, with a hexagonally ordered channel structure, high specific surface area (ABET = 900–1200 m2/g), large pore volume (Vp = 0.70–0.90 cm3/g), average mesopore diameter of about 3 nm, and narrow pore size distribution. Adsorption tests for methylene blue show sorption capacities reaching 39–42 mg/g at alkaline pH. The advantages of producing nickel silicates by this method, in contrast to precipitation from silicon alkoxides, are the low cost of reagents, fire safety, room-temperature processing, and the absence of specific problems associated with the use of ethanol as a solvent, as well as the absence of the inevitable capture of organic matter in the precipitation process. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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22 pages, 4696 KiB  
Article
Unlocking the Potential of Chemically Modified Carbon Gels in Gallic Acid Adsorption
by Regina C. Carvalho, Carlos J. Durán-Valle and Marta Adame-Pereira
Gels 2024, 10(2), 123; https://0-doi-org.brum.beds.ac.uk/10.3390/gels10020123 - 02 Feb 2024
Viewed by 981
Abstract
This study deals with the preparation of adsorbents from a commercial xerogel by chemically modifying its surface with concentrated mineral acids and alkali metal chlorides, their physicochemical characterization, and their use as adsorbents for gallic acid in aqueous solution. Although there are publications [...] Read more.
This study deals with the preparation of adsorbents from a commercial xerogel by chemically modifying its surface with concentrated mineral acids and alkali metal chlorides, their physicochemical characterization, and their use as adsorbents for gallic acid in aqueous solution. Although there are publications on the use of carbon xerogels as adsorbents, we propose and study simple modifications that can change their chemical properties and, therefore, their performance as adsorbents. The adsorbate of choice is gallic acid and, to our knowledge, there is no history of its adsorption with carbon xerogels. The prepared adsorbents have a high specific surface area (347–563 m2 g−1), better pore development for samples treated with alkali metal chlorides than with mineral acids, and are more acidic than the initial xerogel (p.z.c range 2.49–6.87 vs. 7.20). The adsorption equilibrium is reached in <16 h with a kinetic constant between 0.018 and 0.035 h−1 for the pseudo-second-order model. The adsorption capacity, according to the Langmuir model, reaches 62.89 to 83.33 mg g−1. The adsorption properties of the commercial xerogel improved over a wide range of pH values and temperatures. The experimental results indicate that the adsorption process is thermodynamically favored. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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22 pages, 3156 KiB  
Article
Studies on Loading Salicylic Acid in Xerogel Films of Crosslinked Hyaluronic Acid
by Anastasia Maria Mamaligka and Kalliopi Dodou
Gels 2024, 10(1), 54; https://0-doi-org.brum.beds.ac.uk/10.3390/gels10010054 - 11 Jan 2024
Viewed by 1062
Abstract
During the last decades, salicylic acid (SA) and hyaluronic acid (HA) have been studied for a wide range of cosmetic and pharmaceutical applications. The current study investigated the drug loading potential of SA in HA-based crosslinked hydrogel films using a post-loading (osmosis) method [...] Read more.
During the last decades, salicylic acid (SA) and hyaluronic acid (HA) have been studied for a wide range of cosmetic and pharmaceutical applications. The current study investigated the drug loading potential of SA in HA-based crosslinked hydrogel films using a post-loading (osmosis) method of the unmedicated xerogels from saturated aqueous solutions of salicylic acid over a range of pH values. The films were characterized with Fourier-transform infra-red spectroscopy (FT-IR) and ultraviolet-visible (UV-Vis) spectrophotometry in order to elucidate the drug loading profile and the films’ integrity during the loading process. Additional studies on their weight loss (%), gel fraction (%), thickness increase (%) and swelling (%) were performed. Overall, the studies showed significant film disintegration at highly acidic and basic solutions. No drug loading occurred at neutral and basic pH, possibly due to the anionic repulsion between SA and HA, whereas at, pH 2.1, the drug loading was promising and could be detected via UV-Vis analysis of the medicated solutions, with the SA concentration in the xerogel films at 28% w/w. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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18 pages, 4678 KiB  
Article
Ultrasensitive Electroanalytical Detection of Pb2+ and H2O2 Using Bi and Fe—Based Nanoparticles Embedded into Porous Carbon Xerogel—The Influence of Nanocomposite Pyrolysis Temperatures
by Mihai M. Rusu, Carmen I. Fort, Adriana Vulpoi, Lucian Barbu-Tudoran, Monica Baia, Liviu C. Cotet and Lucian Baia
Gels 2023, 9(11), 868; https://0-doi-org.brum.beds.ac.uk/10.3390/gels9110868 - 31 Oct 2023
Cited by 1 | Viewed by 1117
Abstract
Multifunctional materials based on carbon xerogel (CX) with embedded bismuth (Bi) and iron (Fe) nanoparticles are tested for ultrasensitive amperometric detection of lead cation (Pb2+) and hydrogen peroxide (H2O2). The prepared CXBiFe-T nanocomposites were annealed at different [...] Read more.
Multifunctional materials based on carbon xerogel (CX) with embedded bismuth (Bi) and iron (Fe) nanoparticles are tested for ultrasensitive amperometric detection of lead cation (Pb2+) and hydrogen peroxide (H2O2). The prepared CXBiFe-T nanocomposites were annealed at different pyrolysis temperatures (T, between 600 and 1050 °C) and characterized by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption, dynamic light scattering (DLS), and electron microscopies (SEM/EDX and TEM). Electrochemical impedance spectroscopy (EIS) and square wave anodic stripping voltammetry (SWV) performed at glassy carbon (GC) electrodes modified with chitosan (Chi)-CXBiFe-T evidenced that GC/Chi-CXBiFe-1050 electrodes exhibit excellent analytical behavior for Pb2+ and H2O2 amperometric detection: high sensitivity for Pb2+ (9.2·105 µA/µM) and outstanding limits of detection (97 fM, signal-to-noise ratio 3) for Pb2+, and remarkable for H2O2 (2.51 µM). The notable improvements were found to be favored by the increase in pyrolysis temperature. Multi-scale parameters such as (i) graphitization, densification of carbon support, and oxide nanoparticle reduction and purification were considered key aspects in the correlation between material properties and electrochemical response, followed by other effects such as (ii) average nanoparticle and Voronoi domain dimensions and (iii) average CXBiFe-T aggregate dimension. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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16 pages, 16436 KiB  
Article
Actinide Ion (Americium-241 and Uranium-232) Interaction with Hybrid Silica–Hyperbranched Poly(ethylene imine) Nanoparticles and Xerogels
by Ioannis Ioannidis, Ioannis Pashalidis and Michael Arkas
Gels 2023, 9(9), 690; https://0-doi-org.brum.beds.ac.uk/10.3390/gels9090690 - 27 Aug 2023
Viewed by 2949
Abstract
The binding of actinide ions (Am(III) and U(VI)) in aqueous solutions by hybrid silica–hyperbranched poly(ethylene imine) nanoparticles (NPs) and xerogels (XGs) has been studied by means of batch experiments at different pH values (4, 7, and 9) under ambient atmospheric conditions. Both materials [...] Read more.
The binding of actinide ions (Am(III) and U(VI)) in aqueous solutions by hybrid silica–hyperbranched poly(ethylene imine) nanoparticles (NPs) and xerogels (XGs) has been studied by means of batch experiments at different pH values (4, 7, and 9) under ambient atmospheric conditions. Both materials present relatively high removal efficiency at pH 4 and pH 7 (>70%) for Am(III) and U(VI). The lower removal efficiency for the nanoparticles is basically associated with the compact structure of the nanoparticles and the lower permeability and access to active amine groups compared to xerogels, and the negative charge of the radionuclide species is formed under alkaline conditions (e.g., UO2(CO3)34− and Am(CO3)2−). Generally, the adsorption process is relatively slow due to the very low radionuclide concentrations used in the study and is basically governed by the actinide diffusion from the aqueous phase to the solid surface. On the other hand, adsorption is favored with increasing temperature, assuming that the reaction is endothermic and entropy-driven, which is associated with increasing randomness at the solid–liquid interphase upon actinide adsorption. To the best of our knowledge, this is the first study on hybrid silica–hyperbranched poly(ethylene imine) nanoparticle and xerogel materials used as adsorbents for americium and uranium at ultra-trace levels. Compared to other adsorbent materials used for binding americium and uranium ions, both materials show far higher binding efficiency. Xerogels could remove both actinides even from seawater by almost 90%, whereas nanoparticles could remove uranium by 80% and americium by 70%. The above, along with their simple derivatization to increase the selectivity towards a specific radionuclide and their easy processing to be included in separation technologies, could make these materials attractive candidates for the treatment of radionuclide/actinide-contaminated water. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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24 pages, 13927 KiB  
Article
Hybrid Silica Xerogel and Titania/Silica Xerogel Dispersions Reinforcing Hydrophilicity and Antimicrobial Resistance of Leathers
by Michael Arkas, Theofanis Bompotis, Konstantinos Giannakopoulos, Evangelos P. Favvas, Marina Arvanitopoulou, Konstantinos Arvanitopoulos, Labros Arvanitopoulos, Georgia Kythreoti, Michail Vardavoulias, Dimitrios A. Giannakoudakis, Laura Castellsagués and Sara Maria Soto González
Gels 2023, 9(9), 685; https://0-doi-org.brum.beds.ac.uk/10.3390/gels9090685 - 25 Aug 2023
Viewed by 1364
Abstract
Four leather substrates from different animals were treated by dispersions containing hydrophilic composite silica-hyperbranched poly(ethylene imine) xerogels. Antimicrobial activity was introduced by incorporating silver nanoparticles and/or benzalkonium chloride. The gel precursor solutions were also infused before gelation to titanium oxide powders typically employed [...] Read more.
Four leather substrates from different animals were treated by dispersions containing hydrophilic composite silica-hyperbranched poly(ethylene imine) xerogels. Antimicrobial activity was introduced by incorporating silver nanoparticles and/or benzalkonium chloride. The gel precursor solutions were also infused before gelation to titanium oxide powders typically employed for induction of self-cleaning properties. The dispersions from these biomimetically premade xerogels integrate environmentally friendly materials with short coating times. Scanning electron microscopy (SEM) provided information on the powder distribution onto the leathers. Substrate and coating composition were estimated by infrared spectroscopy (IR) and energy-dispersive X-ray spectroscopy (EDS). Surface hydrophilicity and water permeability were assessed by water-contact angle experiments. The diffusion of the leather’s initial components and xerogel additives into the water were measured by Ultraviolet-Visible (UV-Vis) spectroscopy. Protection against GRAM- bacteria was tested for Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae against GRAM+ bacteria for Staphylococcus aureus and Enterococcus faecalis and against fungi for Candida albicans. Antibiofilm capacity experiments were performed against Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, and Candida albicans. The application of xerogel dispersions proved an adequate and economically feasible alternative to the direct gel formation into the substrate’s pores for the preparation of leathers intended for medical uses. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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19 pages, 5461 KiB  
Article
Mercury Bonding to Xerogel: The Interface Fractal Dynamics of the Interaction between Two Complex Systems
by Maria-Alexandra Paun, Vladimir-Alexandru Paun and Viorel-Puiu Paun
Gels 2023, 9(8), 670; https://0-doi-org.brum.beds.ac.uk/10.3390/gels9080670 - 18 Aug 2023
Viewed by 658
Abstract
This study describes novel solid substances founded on chitosan and TEGylated phenothiazine that have a high ability for hydrargyrum recovery from watery liquid solutions. These compounds were taken into account, consisting of two distinct entity interactions inside of the classic fractal dynamics conjecture [...] Read more.
This study describes novel solid substances founded on chitosan and TEGylated phenothiazine that have a high ability for hydrargyrum recovery from watery liquid solutions. These compounds were taken into account, consisting of two distinct entity interactions inside of the classic fractal dynamics conjecture of an “interface”. They were assimilated through fractal-type mathematical objects and judged as such. The bi-stable behavior of two fractally connected objects was demonstrated both numerically and graphically. The fractal character was demonstrated by the fractal analysis made using SEM images of the xerogel compounds with interstitial fixed hydrargyrum. For the first time, SEM helped to verify such samples from two distinct bodies, with the multifractal parameter values being listed in continuation. The fractal dimension of the rectangular mask is D1 = 1.604 ± 0.2798, the fractal dimension of the square mask is D2 = 1.596 ± 0.0460, and the lacunarity is 0.0402. Full article
(This article belongs to the Special Issue Advances in Xerogels: From Design to Applications (2nd Edition))
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