Supercritical CO2 intercalation of layered silicates

Serhatkulu, Gulay K.; Dilek, Çerağ; Gulari, Esin

doi:10.1016/j.supflu.2006.07.028

Cited by 61 publications

(44 citation statements)

References 15 publications

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“…Figure 10A show XRD patterns of the GO powder films obtained after CA structure dissolution in NMP, from CA_GO_2 and CA_GO_2_8h, respectively. The peak at 8.9° (compared to Figure 3SA) is broader and shows an upshifted endset, a broad peak in the range 20-30 2θ became more and more visible 53,54 with increasing SC-CO 2 process time indicating a partial reduction of GO 51,[53][54][55][56] due to removal of oxyfunctional groups and intercalated water, and confirming the indication of TG-MS analysis. It should be noted that it is similar to that of graphite.…”

Section: Samplesupporting

confidence: 75%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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(Stefano Cardea) Phone Number: +39089969365; msarno@unisa.it (Maria Sarno) Phone Number: +39089964057.KEYWORDS: Graphene oxide, Cellulose acetate, Nanocomposite, Supercritical CO 2 . ABSTRACTCellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO 2 as non-solvent, operating at 200 bar and 40 °C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 µm. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidences as Sulphur and Chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO 2 during structures formation; moreover, a partial reduction of GO to graphene was also observed. . Compared to graphene, GO is heavily oxygenated and its basal plane carbon atoms are decorated with epoxide and hydroxyl groups and its edge atoms with carbonyl and carboxyl groups. Hence, GO is highly hydrophilic and the presence of these functional groups reduces interplanar forces, which can improve the interfacial interaction between GO and some polymers and, thus, the dispersion of GO in polymer matrices 2,3 . Many factors can affect the final properties and applications of GO/polymer nanocomposites 4 , among these: kind of GO used, its dispersion state in the polymeric matrix and interfacial interactions, the amount of wrinkling, its network structure in the matrix and its purity.Various attempts have been proposed in the literature to realize GO/polymers composite structures [5][6][7][8][9][10][11][12][13][14][15] . The processes proposed until now (i.e., phase inversion, casting, electrospinning) present several limitations; for example, residues of organic solvents of GO synthesis are typically found at the end of these processes, causing problems, in particular, for biomedical applications. Moreover, a homogeneous distribution of GO in the polymeric matrix is difficult to obtain, since the cohesive forces among GO layers tend to produce restacking. GO composites performance is strongly related to its level of exfoliation (i.e., separation of the layers). Exfoliated GO allows the largest interfacial contact with the polymer matrix, improving the properties of the composites. For this reason, several techniques have been implemented to increase the GO exfoliation degree. In particular, solvent-based exfoliation and thermal exfoliation techniques emerged as two preferred routes for this step [16][17][18][19] . [30][31][32][33] . Due to molecular size of CO 2 and its polarizability, it has the potential to pass through the solid porous layers 34 and, when supercritical conditions are reached, CO 2 diffusivity can favor layers expansion and exfoliation [31][32][33] . It is also possible to...

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Section: Samplesupporting

confidence: 75%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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“…The particle could expand due to the incorporation of CO 2 directly, or it could dehydrate and contract if the supercritical CO 2 has a greater affinity for water molecules than the clay. CO 2 could also act as a delivery fluid (Serhatkulu et al, 2006) to assist in the intercalation of other chemical species in the clay. Krooss et al (2002Krooss et al ( , 2003 considered CO 2 adsorption and diffusion for coal, sandstone, and shale and found that shales can retain CO 2 , although the mechanisms involved are not clear.…”

Section: Introductionmentioning

confidence: 99%

Interaction of carbon dioxide with Na-exchanged montmorillonite at pressures to 640bars: Implications for CO2 sequestration

Giesting¹,

Guggenheim²,

Groos³

et al. 2012

International Journal of Greenhouse Gas Control

165

231

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“…Besides, the CO 2 can be removed entirely from the product without bringing pollution. These unique properties of scCO 2 have yet been exploited for intercalating and exfoliating layered silicates [8][9][10]. Serhatkulu et al [8] used supercritical CO 2 as the processing medium for intercalating the structure of natural clay and depositing CO 2 -philic sugar acetate.…”

Section: Introductionmentioning

confidence: 99%

“…These unique properties of scCO 2 have yet been exploited for intercalating and exfoliating layered silicates [8][9][10]. Serhatkulu et al [8] used supercritical CO 2 as the processing medium for intercalating the structure of natural clay and depositing CO 2 -philic sugar acetate. The XRD results showed the gallery spacing of Cloisite Na + increased from 0.31 to 0.52 nm and low-energy electron diffraction confirmed the deposition of the sugar acetate in the intercalated structure of the clay after scCO 2 processing.…”

Section: Introductionmentioning

confidence: 99%

Influence of physical state of intercalating agents on intercalation process of high speed airflow pretreated montmorillonite in supercritical carbon dioxide

Qin

et al. 2014

Advanced Powder Technology

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Supercritical CO2 intercalation of layered silicates

Cited by 61 publications

References 15 publications

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Interaction of carbon dioxide with Na-exchanged montmorillonite at pressures to 640bars: Implications for CO2 sequestration

Influence of physical state of intercalating agents on intercalation process of high speed airflow pretreated montmorillonite in supercritical carbon dioxide

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Supercritical CO2 intercalation of layered silicates

Cited by 61 publications

References 15 publications

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Interaction of carbon dioxide with Na-exchanged montmorillonite at pressures to 640bars: Implications for CO2 sequestration

Influence of physical state of intercalating agents on intercalation process of high speed airflow pretreated montmorillonite in supercritical carbon dioxide

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Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion