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Gels
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Advanced Hydrogel for Water Treatment
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Advanced Hydrogel for Water Treatment

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

Deadline for manuscript submissions: closed (5 February 2024) | Viewed by 11081

Special Issue Editors

Prof. Dr. Chun Zhao

E-Mail Website
Guest Editor
college and environment and ecology, Chongqing University, Chongqing 400045, China
Interests: advanced oxidation technology; industrial refractory organic wastewater treatment; sludge dewatering; flocculants
Special Issues, Collections and Topics in MDPI journals
Dr. Takehiko Gotoh

E-Mail Website
Guest Editor
Department of Chemical Engineering, Hiroshima University, Higashihiroshima 739-8527, Japan
Interests: functional polymer; polymer gel; environmental responsive; phase transition; kinetics; rheology; adsorption; gel; polymer
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, the shortage of freshwater resources as well as the contamination of aqueous environment are urgent problems worldwide. The development of effective technologies for freshwater harvesting and water decontamination have become urgent demand and research hotspot. Hydrogel, as a novel floatable, durable, anti-fouling, and suitable recycling materials with a porous 3D network structure, is an effective adsorbent to enhance photothermal solar efficiency conversion and removal of series of pollutants from water in desalination and decontaminants during water treatment, respectively.  Hydrogel, which exhibits excellent pollutant adsorption capacity, water holding capacity, water adsorption capacity, and reversible swelling ability, has potential application value in water treatment at large scale.

This Special Issue focuses on the preparation of physical and chemical hydrogel as well as the application of hydrogel for desalination and decontaminant in water purification process, for example, seawater desalination, atmospheric condensation, various pollutants adsorption, and oil-water separation.

Prof. Dr. Chun Zhao
Dr. Takehiko Gotoh
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

  • hydrogel
  • desalination
  • atmospheric condensation
  • heavy metal ions
  • organics removal
  • water treatment

Related Special Issue

Published Papers (7 papers)

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Research

24 pages, 6461 KiB  
Article
Evaluation of the Dye Extraction Using Designed Hydrogels for Further Applications towards Water Treatment
by Magdalena Blachnio and Malgorzata Zienkiewicz-Strzalka
Gels 2024, 10(3), 159; https://doi.org/10.3390/gels10030159 - 21 Feb 2024
Cited by 1 | Viewed by 966
Abstract
In this work, novel chitosan–silica hydrogels were synthesized and investigated by various complementary techniques. The hydrogels were obtained via the immobilization of chitosan (Ch) on the surface of mesoporous cellular foams (MCFs). The latter silica materials were obtained by a sol–gel process, varying [...] Read more.
In this work, novel chitosan–silica hydrogels were synthesized and investigated by various complementary techniques. The hydrogels were obtained via the immobilization of chitosan (Ch) on the surface of mesoporous cellular foams (MCFs). The latter silica materials were obtained by a sol–gel process, varying the composition of the reaction mixture (copolymer Pluronic 9400 or Pluronic 10500) and the ageing temperature conditions (80 °C or 100 °C). The role of the silica phase in the hydrogels was the formation of a scaffold for the biopolymeric chitosan component and providing chemical, mechanical, and thermal stability. In turn, the chitosan phase enabled the binding of anionic pollutions from aqueous solutions based on electrostatic interaction mechanisms and hydrogen bonds. To provide information on structural, morphological, and surface properties of the chitosan–silica hydrogels, analyses such as the low-temperature adsorption/desorption of nitrogen, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR) were performed. Moreover, the verification of the utility of the chitosan–silica hydrogels as adsorbents for water and wastewater treatment was carried out based on kinetic and equilibrium studies of the Acid Red 88 (AR88) adsorption. Adsorption data were analyzed by applying various equations and discussed in terms of the adsorption on heterogeneous solid-surfaces theory. The adsorption mechanism for the AR88 dye–chitosan–silica hydrogel systems was proposed. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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14 pages, 3256 KiB  
Article
Mechanical Properties of Cellulose Aerogel Composites with and without Crude Oil Filling
by Tatjana Paulauskiene, Egle Sirtaute, Arturas Tadzijevas and Jochen Uebe
Gels 2024, 10(2), 135; https://doi.org/10.3390/gels10020135 - 7 Feb 2024
Viewed by 1222
Abstract
Aerogels are an excellent alternative to traditional oil absorbents and are designed to remove oil or organic solvents from water. Cellulose-based aerogels can be distinguished as polymers that are non-toxic, environmentally friendly, and biodegradable. The compression measurement properties of aerogels are often evaluated [...] Read more.
Aerogels are an excellent alternative to traditional oil absorbents and are designed to remove oil or organic solvents from water. Cellulose-based aerogels can be distinguished as polymers that are non-toxic, environmentally friendly, and biodegradable. The compression measurement properties of aerogels are often evaluated using dry samples. Here, oil-soaked, hydrophobized cellulose aerogel samples were examined in comparison to dry samples with and without additional hemp fibers and various levels of starch for crosslinking. The samples were characterized by compression measurement properties and filmed to evaluate the regeneration of the sorbent with repeated use. Overall, the measurements of the mechanical properties for the dry samples showed good reproducibility. The Young’s modulus of samples with additional hemp fibers is significantly increased and also shows higher strength than samples without hemp fibers. However, samples without hemp fibers showed slightly better relaxation after compression. Oil acts as a weak plasticizer for all aerogel samples. However, it is important to note that the oil does not cause the samples to decompose in the way unmodified cellulose aerogels do in water. Therefore, using hydrophobized cellulose aerogels as sorbents for oil in a sea or harbor with swell means that they can be collected in their entirety even after use. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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14 pages, 2763 KiB  
Article
Adsorption of Levofloxacin onto Graphene Oxide/Chitosan Composite Aerogel Microspheres
by Pengpai Miao, Jie Gao, Xiaobing Han, Yuan Zhao and Tao Chen
Gels 2024, 10(1), 81; https://doi.org/10.3390/gels10010081 - 21 Jan 2024
Cited by 2 | Viewed by 1029
Abstract
The removal of pharmaceutical residues from water resources using bio-based materials is very important for human safety and health. Bio-based graphene oxide/chitosan (GO/CS) aerogel microspheres were fabricated with emulsification and cross-linking, followed by freeze drying, and were used for the adsorption of levofloxacin [...] Read more.
The removal of pharmaceutical residues from water resources using bio-based materials is very important for human safety and health. Bio-based graphene oxide/chitosan (GO/CS) aerogel microspheres were fabricated with emulsification and cross-linking, followed by freeze drying, and were used for the adsorption of levofloxacin (LOF). The obtained GO/CS aerogel microspheres were characterized with scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and thermogravimetry (TG). The effects of GO content, pH value, and temperature on their adsorption capacity were investigated. With the incorporation of 40 wt% GO, the adsorption capacity increased from 9.9 to 45.6 mg/g, and the highest adsorption capacity, 51.5 mg/g, was obtained at pH = 8 and T = 25 °C. In addition, to obtain deeper insight into the adsorption process, the thermodynamics and kinetics of the process were also investigated with four different models of LOF adsorption. The thermodynamic modeling results revealed that LOF adsorption is exothermic, and the kinetic investigation demonstrated that LOF adsorption is generally consistent with a pseudo-first-order rate law. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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22 pages, 5399 KiB  
Article
Performance of Dye Removal from Single and Binary Component Systems by Adsorption on Composite Hydrogel Beads Derived from Fruits Wastes Entrapped in Natural Polymeric Matrix
by Cristina-Gabriela Grigoraș, Andrei-Ionuț Simion, Lidia Favier, Cătălin Drob and Lucian Gavrilă
Gels 2022, 8(12), 795; https://doi.org/10.3390/gels8120795 - 3 Dec 2022
Cited by 4 | Viewed by 2057
Abstract
The treatment of contaminated water is currently a major concern worldwide. This work was directed towards the preparation of a composite hydrogel by entrapping cherry stones powder on chitosan, which is known as one of the most abundant natural polymers. The synthesized material [...] Read more.
The treatment of contaminated water is currently a major concern worldwide. This work was directed towards the preparation of a composite hydrogel by entrapping cherry stones powder on chitosan, which is known as one of the most abundant natural polymers. The synthesized material was characterized by scanning electron microscopy, by Fourier transform infrared spectroscopy, and by the point of zero charge determination. Its ability to remove two azo dyes models (Acid Red 66 and Reactive Black 5) existing in single form and in binary mixture was evaluated. Response Surface Methodology–Central Composite Design was used to optimize three parameters affecting the process while targeting the lowest final contaminant concentrations. The best results were obtained at pH 2, an adsorbent dose of 100 g/L, and a temperature of 30 °C, when more than 90% of the pollutants from the single component systems and more than 70% of those of the binary mixtures were removed from their aqueous solutions. The adsorption process was in accordance with Elovich and pseudo-second-order kinetic models, and closely followed the Freundlich and Temkin equilibrium isotherms. The obtained results led to the conclusion that the prepared hydrogel composite possesses the ability to successfully retain the target molecules and that it can be considered as a viable adsorbent material. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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12 pages, 3159 KiB  
Article
Auto-Continuous Synthesis of Robust and Hydrophobic Silica Aerogel Microspheres from Low-Cost Aqueous Sodium Silicate for Fast Dynamic Organics Removal
by Ziqian Sun, Zhiyang Zhao, Yong Kong, Jian Ren, Xing Jiang and Xiaodong Shen
Gels 2022, 8(12), 778; https://doi.org/10.3390/gels8120778 - 28 Nov 2022
Cited by 10 | Viewed by 1892
Abstract
An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica [...] Read more.
An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica aerogel microsphere (RSAM) was prepared by polymer cross-linking on the framework of the silica gel. The pH value of the reaction system and the temperature of the coagulating bath were critical to form perfect SAMs with a diameter of 3.0 ± 0.2 mm. The grafted methyl groups are thermally stable up to 400 °C. Polymer cross-linking increased the strength significantly, owing to the polymer coating on the framework of silica aerogel. The pore volumes of HSAM (6.44 cm3/g) and RSAM (3.17 cm3/g) were much higher than their state-of-the-art counterparts. Their specific surface areas were also at a high level. The HSAM and RSAM showed high organic sorption capacities, i.e., 17.9 g/g of pump oil, 11.8 g/g of hexane, and 22.2 mg/g of 10 mg/L methyl orange. The novel preparation method was facile, cost-effective, safe, and eco-friendly, and the resulting SAM sorbents were exceptional in capacity, dynamics, regenerability, and stability. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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17 pages, 11848 KiB  
Article
Structure and Adsorption Performance of Cationic Entermorpha prolifera Polysaccharide-Based Hydrogel for Typical Pollutants: Methylene Blue, Cefuroxime, and Cr (VI)
by Xiaolei Ma, Duomo Duan, Jinbin Chen and Baolong Xie
Gels 2022, 8(9), 546; https://doi.org/10.3390/gels8090546 - 29 Aug 2022
Cited by 1 | Viewed by 1447
Abstract
Hydrogels with polysaccharides as high polymer substrates have surprising advantages in wastewater treatment with complex components. Therefore, in this study, polysaccharides named EPS were extracted from Enteromorpha prolifera, a coastal pollutant with a wide range of sources, and cationic modification was performed [...] Read more.
Hydrogels with polysaccharides as high polymer substrates have surprising advantages in wastewater treatment with complex components. Therefore, in this study, polysaccharides named EPS were extracted from Enteromorpha prolifera, a coastal pollutant with a wide range of sources, and cationic modification was performed to obtain CAEPS, the hydrogel with a double network structure was prepared based on EPS and CAEPS. Meanwhile, the structural characteristic of EPS and CAEPS-based hydrogel were identified by HPLC, AFM, FT-IR, TGA, SEM-EDS, Pore size distribution, and WCA, which showed that the porosity, apparent (skeletal) density, and hydrophilicity of CAEPS-hydrogels. We used nonlinear isotherms to uncover the adsorption mechanism of hydrogel applied to the water environment containing three typical pollutants (Methylene blue, Cefuroxime, and Cr (VI)). The results showed that the adsorption isotherm of the two hydrogels fit the Langmuir isotherm model, which indicated the monolayer adsorption of the pollution factor onto EPS- and CAEPS-hydrogels. The maximum adsorption capacities of CAEPS-hydrogels were higher than EPS-hydrogels, which indicated the microstructure and adsorption performance of the CAEPS-hydrogel are strengthened. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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17 pages, 4191 KiB  
Article
Fabrication of 3D Gelatin Hydrogel Nanocomposite Impregnated Co-Doped SnO2 Nanomaterial for the Catalytic Reduction of Environmental Pollutants
by Hadi M. Marwani, Shahid Ahmad and Mohammed M. Rahman
Gels 2022, 8(8), 479; https://doi.org/10.3390/gels8080479 - 29 Jul 2022
Cited by 6 | Viewed by 1602
Abstract
In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO2 intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO2 doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin [...] Read more.
In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO2 intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO2 doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin polymer, which led to the formation of GL/Co-SnO2 hydrogel nanocomposite. GL/Co-SnO2 hydrogel nanocomposite was fully characterized by using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR). The FESEM images indicate that the Co-SnO2 composite has a spherical structure on the GL matrix while EDX elucidates the elemental composition of each atom in the crosslinked GL/Co-SnO2 hydrogel nanocomposite. The GL/Co-SnO2 nanocomposite was checked for the reduction of various pollutants, including 2-nitro-phenol (2-NP), 2,6-dinitro-phenol (2,6-DNP), 4-nitro-phenol (4-NP), Congo red (CR), and methyl orange (MO) dyes with a strong sodium borohydride (NaBH4) reducing agent. The GL/Co-SnO2 nanocomposite synergistically reduced the MO in the presence of the reducing agent with greater reduction rate of 1.036 min−1 compared to other dyes. The reduction condition was optimized by changing various parameters, such as the catalyst amount, dye concentration, and the NaBH4 amount. Moreover, the GL/Co-SnO2 nanocomposite catalyst can be easily recovered, is recyclable, and revealed minimal loss of nanomaterials. Full article
(This article belongs to the Special Issue Advanced Hydrogel for Water Treatment)
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