Covalently linked graphene oxide/reduced graphene oxide-methoxylether polyethylene glycol functionalised silica for scavenging of estrogen: Adsorption performance and mechanism

Akpotu, Samson O.; Lawal, Isiaka A.; Moodley, Brenda; Ofomaja, Augustine E.

doi:10.1016/j.chemosphere.2019.125729

Cited by 33 publications

(26 citation statements)

References 52 publications

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“…Such data ( Figure 4 and Figure 5 ) indicated that the hormone-like dexamethasone binds with high specificity and selectivity to the fabricated membrane. Several studies have demonstrated the absorption capacity of rGO foam/ polymer (PEI / polyethylene glycol) for pharmaceutical contaminants such as 17β-estradiol [ 40 ] or toxic cations from water [ 41 ]. However, these studies are not based on the importance of the affinity and specificity of the adsorption of contaminants by using a biomolecule such as aptamers.…”

Section: Resultsmentioning

confidence: 99%

Graphene Oxide Membrane Immobilized Aptamer as a Highly Selective Hormone Removal

et al. 2020

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Three-dimensional (3D) reduced graphene oxide (rGO) modified by polyethyleneimine (PEI) was prepared and functionalized by fluorophore-labeled dexamethasone-aptamer (Flu-DEX-apt) via π–π stacking interaction. The rGO/PEI/Flu-DEX-apt was used as a selective membrane for dexamethasone hormone removal from water. The prepared rGO/PEI/Flu-DEX-apt membranes were stable, insoluble, and easily removable from liquid media. The membrane was characterized by Raman spectroscopy, scanning electron spectroscopy, and FTIR spectroscopy. The rGO/PEI/Flu-DEX-apt membrane showed high sensitivity and specificity toward the dexamethasone hormone in the presence of other steroid hormone analogs, such as progesterone, estrone, estradiol, and 19-norethindrone. The fluorescence and UV–visible spectroscopy were used to confirm the membranes performance and the quantification of hormones removal. The resulting data clearly show that the graphene oxide concentration influence the aptamers and analytes interaction (π–π stacking interaction). It was found that by varying the graphene oxide concentration yields to different porosities of rGO/PEI/Flu-DEX-apt membranes affects the adsorption recovery rate, as well as the specificity and selectivity toward the dexamethasone hormone.

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Section: Resultsmentioning

confidence: 99%

Graphene Oxide Membrane Immobilized Aptamer as a Highly Selective Hormone Removal

et al. 2020

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“…Amine-functionalized kaolin clay (K-NH 2 ) was synthesized as previously reported. 17 2.2.1. GO-PEG Synthesis.…”

Section: Methodsmentioning

confidence: 99%

“…31a The −C�O− stretching vibrations from carboxyl and carbonyl functional groups were observed at 1725 cm −1 , while vibrations of the −C�C− and −C−C− bonds of the GO graphitic framework were at 1634 and 1572 cm −1 , respectively. 17 The −C−OH and C−O stretching vibrations were observed at 1389 and 1068 cm −1 , respectively. KGO had hybrid absorption vibrations that were reflective of its precursors (GO and kaolin); however, there were new peaks and a shift in peak positions for Si−O−Si (459 cm −1 ) and Si− O−Al (531 cm −1 ) bending vibrations.…”

Section: Characterization Of Adsorbentsmentioning

confidence: 98%

“…The hydrophilic nature of GO causes difficulty in separation from adsorbate solution. 17 To overcome aggregation/separation, GO is anchored on a solid support, ensuring that adsorption capacity is maximized, and separation issues are eliminated. Studies show that anchoring GO on support materials led to increased adsorption of metals and pharmaceuticals.…”

Section: Introductionmentioning

confidence: 99%

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Engineered Geomedia Kaolin Clay-Reduced Graphene Oxide–Polymer Composite for the Remediation of Olaquindox from Water

et al. 2022

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Globally, there is an upsurge in the use of unregulated veterinary pharmaceuticals with enhanced release into the environment, resulting in water pollution, which is difficult to remediate. To address this issue, we synthesized and characterized highly hydrophobic three-dimensional ordered engineered geomedia with multiple channels. Kaolin clay (K) was functionalized with either graphene oxide (GO) synthesized via Tour’s method or reduced GO in situ with covalently linked methoxyether polyethylene glycol (GO-PEG) using a simple and easily scalable amidation reaction. This was done to enhance the adsorption of olaquindox, a veterinary antibiotic. The X-ray diffraction profile confirmed the grafting of GO and GO-PEG to kaolin. Morphological analysis revealed the architecture of thin films of GO/GO-PEG grafted on the kaolin surface with extensive porosity. Energy-dispersive X-ray mapping, infra-red spectra, and elemental analysis confirmed the successful synthesis of the engineered geomedia composite of K, GO/rGO, and PEG (KrGO-PEG). Due to multiple surface functional groups of polyamide and amido-carbonic groups on the KrGO-PEG composite, it was suitable for olaquindox adsorption. In batch sorption studies of 0.5XKrO-PEG, the effect of pH (2–10) was negligible but with fast equilibrium time (2–1440 min) at 30 min, while the kinetics and equilibrium data suited the pseudo-second order and Langmuir models, respectively. The maximum adsorption value obtained for the composite was 59.5 mg/g; the higher the GO content, the higher the adsorption. The sorption mechanism was majorly through hydrophobic and π–π interactions. Regenerated/reused adsorbents after 4 cycles had the same efficacy in remediating olaquindox from simulated/real water.

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“…GO has shown brilliant removal efficiency toward many organic pollutants including polycyclic aromatic hydrocarbons (PAHs) and their derivatives, pharmaceuticals, dyes, and pesticides . The proposed mechanism of adsorption of these organic compounds has been reported to be via π–π interactions, which are hydrophobic between the pollutants and GO. , The same aggregate problem observed in CNTs has also been reported in GO due to the strong force of van der Waals between their single layers . Also, it is very difficult to recover GO from an aqueous medium because of the oxygen-containing groups that are in abundance on the surface. , …”

Section: Introductionmentioning

confidence: 96%

Noncovalent Graphene Oxide Functionalized with Ionic Liquid: Theoretical, Isotherm, Kinetics, and Regeneration Studies on the Adsorption of Pharmaceuticals

Lawal

Akpotu

et al. 2020

Ind. Eng. Chem. Res.

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Sulfamethoxazole (SMZ), carbamazepine (CBZ), and ketoprofen (KET) adsorption using graphene oxide (GO) functionalized with ionic liquids (IL) was investigated. Ionic liquid 1-hexyl 3-decahexyl imidazolium was synthesized and characterized using high resolution-mass spectrometry and nuclear magnetic resonance ( 1 H and 13 C NMR). GO and GO−IL were synthesized and characterized using thermal gravimetric analysis, X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, surface area and porosity analysis, and ζ potentials. Computational, isotherm, kinetics, and regeneration studies were carried out to determine the adsorption capacity, adsorption mechanism, and reusability of the material for the adsorption of SMZ, CBZ, and KET. Density functional theory (DFT) and our own N-layered integrated molecular orbital and molecular mechanics (ONIOM) (quantum mechanics and molecular mechanics) approach were applied to describe the nature of the interaction, energetics, charge distribution, and pH effect during the sorption of the pharmaceutical compounds on the adsorbents at the molecular level. Effects of solution pH, contact time, adsorbent dosage, and energetics on the selected pharmaceuticals were also investigated experimentally. The pH plays a significant role on the adsorption of SMZ and KET but has no significant effect on the adsorption of CBZ on both GO and GO−IL. Pseudo-second-order and Langmuir models best explained the kinetics and adsorption isotherm, respectively. GO−IL showed superior adsorption efficiency for the selected pharmaceuticals when compared to GO.

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Covalently linked graphene oxide/reduced graphene oxide-methoxylether polyethylene glycol functionalised silica for scavenging of estrogen: Adsorption performance and mechanism

Cited by 33 publications

References 52 publications

Graphene Oxide Membrane Immobilized Aptamer as a Highly Selective Hormone Removal

Graphene Oxide Membrane Immobilized Aptamer as a Highly Selective Hormone Removal

Engineered Geomedia Kaolin Clay-Reduced Graphene Oxide–Polymer Composite for the Remediation of Olaquindox from Water

Noncovalent Graphene Oxide Functionalized with Ionic Liquid: Theoretical, Isotherm, Kinetics, and Regeneration Studies on the Adsorption of Pharmaceuticals

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