Green and Solvent-Free Supercritical CO<sub>2</sub>-Assisted Production of Superparamagnetic Graphene Oxide Aerogels: Application as a Superior Contrast Agent in MRI

Borrás, Alejandro; Fraile, Julio; Rosado, Albert; Marbán, Gregorio; Tobias, Gerard; López‐Periago, Ana M.; Domingo, Concepción

doi:10.1021/acssuschemeng.0c00149

Cited by 21 publications

(11 citation statements)

References 63 publications

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“…The best way to maintain GO exfoliated in a dry product is through the formation of highly porous aerogels, which can be constructed using a low-temperature supercritical carbon dioxide (scCO 2 ) method to induce gelation, as it was demonstrated in our laboratories. , The method is also able to produce robust nanocomposites involving nonreduced GO. This promising technique is here extended to the synthesis of low-density MOF@GO composite aerogels by adapting the scCO 2 protocol to ex situ and in situ methods.…”

Section: Introductionmentioning

confidence: 99%

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation

Rosado

Borrás

Fraile

et al. 2021

ACS Appl. Nano Mater.

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The development of nanostructured composites made of metal−organic frameworks (MOFs) and graphene-based components, including exfoliated nanoplates of graphene oxide (GO) or reduced (rGO) graphene oxide, is an area of great interest in gas storage and separation. To improve the industrial viability, it is commonly demanded to build these nanocomposites with the shape of compact units, such as monoliths, foams, pellets, or films. Methods to generate those 3D nanocomposites involving rGO are abundant; however, they become scarce when GO is the desired support due to the difficulty in maintaining the carbon matrix oxidized during the structuration process. In this work, a methodology based on the use of supercritical CO 2 (scCO 2 ) is described for the synthesis of nanocomposites involving a discontinuous MOF phase, e.g. nanoparticles (NPs) of HKUST-1, decorating the surface of a continuous GO matrix, with surface oxygen groups favoring MOF attachment. The use of this new supercritical methodology allows the nanostructuration of the composite in the form of 3D aerogels while avoiding the reduction of GO. Enhanced values of textural properties, determined by low-temperature N 2 adsorption−desorption, were observed for the nanocomposites in comparison to the values calculated for similar physical mixtures, highlighting an increase of 40−45% in the value of the surface area for samples with a high percentage of HKUST-1. Moreover, the composite aerogels, displaying a type II isotherm, outperform pristine HKUST-1 in regard to the CH 4 practical working capacity at high pressure. Particularly, a composite exhibiting more than 2-fold the working capacity of net HKUST-1 NPs was obtained. Columns involving the composite aerogel as the stationary phase were used to study the separation of N 2 /CO 2 and CH 4 /CO 2 gas mixtures. The results showed a high selectivity of the nanostructured HKUST-1@GO composites for CO 2 , with breakthrough times of ca. 20 min g −1 and stable cyclic operations.

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Section: Introductionmentioning

confidence: 99%

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation

Rosado

Borrás

Fraile

et al. 2021

ACS Appl. Nano Mater.

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“…An alternative is the use of magnetic aerogels, in which the separation can be carried out with the aid of an external magnet [ 49 , 50 , 51 ]. The synthesis of magnetic aerogels involving superparamagnetic iron oxide nanoparticles (SPIONs) can be easily achieved using the supercritical route, as demonstrated previously by some of us [ 52 ]. The SPIONs were added in the desired percentage (ca.…”

Section: Resultsmentioning

confidence: 99%

Graphene Oxide/Polyethylenimine Aerogels for the Removal of Hg(II) from Water

Borrás

Henriques

Gonçalves

et al. 2022

Gels

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This article reports the synthesis of an aerogel involving reduced graphene oxide (rGO) and polyethylenimine (PEI), and describes its potential application as an effective sorbent to treat Hg(II) contaminated water. The rGO/PEI sorbent was synthetized using a supercritical CO2 method. N2 physisorption, electron microscopy, and elemental mapping were applied to visualize the meso/macroporous morphology formed by the supercritical drying. The advantages of the synthetized materials are highlighted with respect to the larger exposed GO surface for the PEI grafting of aerogels vs. cryogels, homogeneous distribution of the nitrogenated amino groups in the former and, finally, high Hg(II) sorption capacities. Sorption tests were performed starting from water solutions involving traces of Hg(II). Even though, the designed sorbent was able to eliminate almost all of the metal from the water phase, attaining in very short periods of time residual Hg(II) values as low as 3.5 µg L−1, which is close to the legal limits of drinking water of 1–2 µg L−1. rGO/PEI exhibited a remarkably high value for the maximum sorption capacity of Hg(II), in the order of 219 mg g−1. All of these factors indicate that the designed rGO/PEI aerogel can be considered as a promising candidate to treat Hg(II) contaminated wastewater.

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“…This makes it relatively easy to self-assemble graphene oxide (GO) into a monolith. In addition, cutting-edge techniques like 3D printing, soft template assembly, supercritical fluid technique, and electrochemical deposition are also exploited. − Unfortunately, these methods are either expensive or cumbersome.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly of a Graphene Oxide Liquid Crystal for Water Treatment

Shao

Zhong

et al. 2022

ACS Appl. Mater. Interfaces

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Adsorbents, especially those with high removal efficiency, long life, and multi-purpose capabilities, are the most crucial components in an adsorption system. By taking advantage of the liquid-like mobility and crystal-like ordering of liquid crystal materials, a liquid crystal induction method is developed and applied to construct three-dimensional graphene-based adsorbents featuring excellent shape adaptability, a distinctive pore structure, and abundant surface functional groups. When the monoliths are used for water restoration, the large amount of residual oxygen-containing groups is more susceptible to electrophilic attack, thus contributing to cation adsorption (up to 705.4 mg g–1 for methylene blue), while the connected microvoids between the aligned graphene oxide sheets facilitate mass transfer, e.g., the high adsorption capacity for organic pollutants (196.2 g g–1 for ethylene glycol) and the high evaporation rate for water (4.01 kg m–2 h–1). This work gives a practical method for producing high-performance graphene-based functional materials for those applications that are sensitive to surface and mass transfer properties.

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Green and Solvent-Free Supercritical CO₂-Assisted Production of Superparamagnetic Graphene Oxide Aerogels: Application as a Superior Contrast Agent in MRI

Abstract: Supporting Information: EDS mapping of Fe 3 O 4 @GO (S1), XPS calculations for the surface composition of the samples.

Cited by 21 publications

References 63 publications

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation

Graphene Oxide/Polyethylenimine Aerogels for the Removal of Hg(II) from Water

Self-Assembly of a Graphene Oxide Liquid Crystal for Water Treatment

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Green and Solvent-Free Supercritical CO2-Assisted Production of Superparamagnetic Graphene Oxide Aerogels: Application as a Superior Contrast Agent in MRI

Abstract: Supporting Information: EDS mapping of Fe 3 O 4 @GO (S1), XPS calculations for the surface composition of the samples.

Cited by 21 publications

References 63 publications

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO2 and CH4 Adsorption and Separation

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO2 and CH4 Adsorption and Separation

Graphene Oxide/Polyethylenimine Aerogels for the Removal of Hg(II) from Water

Self-Assembly of a Graphene Oxide Liquid Crystal for Water Treatment

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Product

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Green and Solvent-Free Supercritical CO₂-Assisted Production of Superparamagnetic Graphene Oxide Aerogels: Application as a Superior Contrast Agent in MRI

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation

HKUST-1 Metal–Organic Framework Nanoparticle/Graphene Oxide Nanocomposite Aerogels for CO₂ and CH₄ Adsorption and Separation