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Georgiou E, Raptopoulos G, Anastopoulos I, Giannakoudakis DA, Arkas M, Paraskevopoulou P, Pashalidis I. Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents-A Critical Review. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13020363. [PMID: 36678117 PMCID: PMC9866664 DOI: 10.3390/nano13020363] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/03/2023] [Accepted: 01/09/2023] [Indexed: 06/12/2023]
Abstract
Aerogels are a class of lightweight, nanoporous, and nanostructured materials with diverse chemical compositions and a huge potential for applications in a broad spectrum of fields. This has led the IUPAC to include them in the top ten emerging technologies in chemistry for 2022. This review provides an overview of aerogel-based adsorbents that have been used for the removal and recovery of uranium from aqueous environments, as well as an insight into the physicochemical parameters affecting the adsorption efficiency and mechanism. Uranium removal is of particular interest regarding uranium analysis and recovery, to cover the present and future uranium needs for nuclear power energy production. Among the methods used, such as ion exchange, precipitation, and solvent extraction, adsorption-based technologies are very attractive due to their easy and low-cost implementation, as well as the wide spectrum of adsorbents available. Aerogel-based adsorbents present an extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg−1 (2088 g kg−1). The adsorption data generally follow the Langmuir isotherm model, and the kinetic data are in most cases better described by the pseudo-second-order kinetic model. An evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔH0, ΔS0 > 0). Spectroscopic studies (e.g., FTIR and XPS) indicate that the adsorption is based on the formation of inner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited, suggesting further developments of aerogel materials that could be modified by surface derivatization with chelating agents (e.g., salophen and iminodiacetate) presenting high selectivity for uranyl moieties.
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Affiliation(s)
- Efthalia Georgiou
- Radioanalytical and Environmental Chemistry Group, Department of Chemistry, University of Cyprus, P.O. Box 20537, Nicosia CY-1678, Cyprus
| | - Grigorios Raptopoulos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece
| | - Ioannis Anastopoulos
- Department of Agriculture, University of Ioannina, UoI Kostakii Campus, 47100 Arta, Greece
| | | | - Michael Arkas
- Demokritos National Centre for Scientific Research, Institute of Nanoscience and Nanotechnology, 15771 Athens, Greece
| | - Patrina Paraskevopoulou
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece
| | - Ioannis Pashalidis
- Radioanalytical and Environmental Chemistry Group, Department of Chemistry, University of Cyprus, P.O. Box 20537, Nicosia CY-1678, Cyprus
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Li J, Jiang S, Ding L, Wang L. Reaction kinetics and properties of MDI base poly (urethane-isocyanurate) network polymers. Des Monomers Polym 2021; 24:265-273. [PMID: 34471398 PMCID: PMC8405120 DOI: 10.1080/15685551.2021.1971858] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/19/2021] [Indexed: 11/25/2022] Open
Abstract
Since the trimerization of isocyanate occurs easily and controllably to form a clear trifunctional isocyanate ring, this reaction is an ideal candidate for the synthesis of a clear poly(urethane-isocyanurate) network polymer. Poly(urethane-isocyanurate) network polymer (PUI) was prepared from diphenylmethane diisocyanate (MDI) and propylene glycol (PPG) by cyclotrimerization of isocyanate group (NCO). It was proved that the expected product was successfully prepared by NCO determination, fourier transform infrared (FTIR) and gel permeation chromatography (GPC) characterization. The mechanical and thermal properties were characterized. Through the effects of catalyst dosage, polyurethane prepolymer molecular weight, reaction time, reaction temperature and MDI addition on the reaction process, it is determined that under certain other conditions, the step heating method is better for cyclotrimerization reaction. Generally, the better heating conditions are 60 °C/1 h + 80 °C/4 h + 100 °C/2 h + 120 °C/2 h + 140 °C/2 h + 160 °C/2 h. The results of thermogravimetric analysis (TGA) and mechanical properties showed that with the increase of cross-linking points in the polymer structure, the thermal stability, tensile strength, tensile modulus and hardness of PUI increased, while the elongation at break decreased significantly. The glass transition temperature (Tg) of PUI is around 45 °C, and it can be seen that the elastic modulus of the material can range from 58 to 1980 MPa. X-ray diffraction results show that the rubber phase represented by the flexible segment and the plastic phase represented by the rigid structure are amorphous.
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Affiliation(s)
- Juan Li
- Department of Polymer and Composite Material, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, China
| | - Shengling Jiang
- Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, China
| | - Liang Ding
- Department of Polymer and Composite Material, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, China
| | - Lingfang Wang
- Department of Polymer and Composite Material, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, China
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Chriti D, Raptopoulos G, Brandenburg B, Paraskevopoulou P. Large, Rapid Swelling of High- cis Polydicyclopentadiene Aerogels Suitable for Solvent-Responsive Actuators. Polymers (Basel) 2020; 12:polym12051033. [PMID: 32370122 PMCID: PMC7284835 DOI: 10.3390/polym12051033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 11/16/2022] Open
Abstract
High-cis polydicyclopentadiene (PDCPD) aerogels were synthesized using ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) with a relatively air-stable ditungsten catalytic system, Na[W2(-Cl)3Cl4(THF)2]·(THF)3 (W2; (W 3 W)6+, a΄2e΄4), and norbornadiene (NBD)as a co-initiator. These aerogels are compared in terms of chemical structure and material properties with literature PDCPD aerogels obtained using well-established Ru-based alkylidenes as catalysts. The use of NBD as a co-initiator enhances the degree of crosslinking versus the more frequently used phenylacetylene (PA), yielding materials with a controlled molecular structure that would persist solvent swelling. Indeed, those PDCPD aerogels absorb selected organic solvents (e.g., chloroform, tetrahydrofuran) and swell rapidly, in some cases up to 4 times their original volume within 10 min, thus showing their potential for applications in chemical sensors and solvent-responsive actuators. The advantage of aerogels versus xerogels or dense polymers for these applications is their open porosity, which provides rapid access of the solvent to their interior, thus decreasing the diffusion distance inside the polymer itself, which in turn accelerates the response to the solvents of interest.
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Affiliation(s)
- Despoina Chriti
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece; (D.C.); (G.R.)
| | - Grigorios Raptopoulos
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece; (D.C.); (G.R.)
| | | | - Patrina Paraskevopoulou
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece; (D.C.); (G.R.)
- Correspondence: ; Tel.: +30-210-727-4381; Fax: +30-210-727-4782
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Paraskevopoulou P, Smirnova I, Athamneh T, Papastergiou M, Chriti D, Mali G, Čendak T, Raptopoulos G, Gurikov P. Polyurea-crosslinked biopolymer aerogel beads. RSC Adv 2020. [DOI: 10.1039/d0ra07337g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Polyurea-crosslinked calcium alginate and chitosan aerogel beads: novel fibrous biopolymer-based aerogels.
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Affiliation(s)
- Patrina Paraskevopoulou
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Irina Smirnova
- Institute of Thermal Separation Processes
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
| | - Tamara Athamneh
- Institute of Thermal Separation Processes
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
| | - Maria Papastergiou
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Despoina Chriti
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Gregor Mali
- National Institute of Chemistry
- 1000 Ljubljana
- Slovenia
| | - Tomaž Čendak
- National Institute of Chemistry
- 1000 Ljubljana
- Slovenia
| | - Grigorios Raptopoulos
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Pavel Gurikov
- Laboratory for Development and Modelling of Novel Nanoporous Materials
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
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Rewatkar PM, Saeed AM, Majedi Far H, Donthula S, Sotiriou-Leventis C, Leventis N. Polyurethane Aerogels Based on Cyclodextrins: High-Capacity Desiccants Regenerated at Room Temperature by Reducing the Relative Humidity of the Environment. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34292-34304. [PMID: 31490651 DOI: 10.1021/acsami.9b10755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polyurethane aerogels were prepared from a rigid aromatic triisocyanate (tris(4-isocyanatophenyl)methane) and cage-shaped α- and β-cyclodextrins as rigid polyols. Gelation was carried out in DMF using dibutyltin dilaurate as catalyst. Wet-gels were dried to aerogels (abbreviated as α- or β-CDPU-xx) with supercritical fluid CO2. "xx" stands for the percent weight of the two monomers in the sol and was varied at two levels for each cyclodextrin: 2.5% and 15%. All aerogels were characterized with solid-state 13C and 15N NMR, CHN analysis, FTIR, XPS, SEM, and gas (N2 and CO2) sorption porosimetry. α- and β-CDPU-xx aerogels were investigated as desiccants at room temperature. All materials had relatively higher capacities for water adsorption from high-humidity environments (99%) than typical commercial desiccants like silica or Drierite. However, α-CDPU-2.5 aerogels did stand out with a water uptake capacity reaching 1 g of H2O per gram of material. Most importantly though, adsorbed water could be released quantitatively without heating, by just reducing the relative humidity of the environment to 10%. All α- and β-CDPU-xx aerogel samples were cycled between humid and dry environments 10 times. Their unusual behavior was traced to filling smaller mesopores with water and was attributed to a delicate balance of enthalpic (H-bonding) and entropic factors, whereas the latter are a function of pore sizes.
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Affiliation(s)
- Parwani M Rewatkar
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Adnan Malik Saeed
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Hojat Majedi Far
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Suraj Donthula
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Chariklia Sotiriou-Leventis
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Nicholas Leventis
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
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Synthetic Polymer Aerogels in Particulate Form. MATERIALS 2019; 12:ma12091543. [PMID: 31083421 PMCID: PMC6539448 DOI: 10.3390/ma12091543] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/22/2019] [Accepted: 05/06/2019] [Indexed: 11/17/2022]
Abstract
Aerogels have been defined as solid colloidal or polymeric networks of nanoparticles that are expanded throughout their entire volume by a gas. They have high surface areas, low thermal conductivities, low dielectric constants, and high acoustic attenuation, all of which are very attractive properties for applications that range from thermal and acoustic insulation to dielectrics to drug delivery. However, one of the most important impediments to that potential has been that most efforts have been concentrated on monolithic aerogels, which are prone to defects and their production requires long and costly processing. An alternative approach is to consider manufacturing aerogels in particulate form. Recognizing that need, the European Commission funded “NanoHybrids”, a 3.5 years project under the Horizon 2020 framework with 12 industrial and academic partners aiming at aerogel particles from bio- and synthetic polymers. Biopolymer aerogels in particulate form have been reviewed recently. This mini-review focuses on the emerging field of particulate aerogels from synthetic polymers. That category includes mostly polyurea aerogels, but also some isolated cases of polyimide and phenolic resin aerogels. Particulate aerogels covered include powders, micro granules and spherical millimeter-size beads. For the benefit of the reader, in addition to the literature, some new results from our laboratory concerning polyurea particle aerogels are also included.
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