Adsorption of Mercury on Oxidized Graphenes

Tene, Talia; Bellucci, Stefano; Guevara, Marco; Arias, Fabian Arias; Paguay, Miguel Ángel Sáez; Moyota, John Marcos Quispillo; Arias, Melvin; Scarcello, Andrea; Gomez, Cristian Vacacela; Straface, Salvatore; Caputi, Lorenzo; Torres, Javier

doi:10.3390/nano12173025

Cited by 15 publications

(4 citation statements)

References 59 publications

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“…GO offers several advantages over pure graphene, including improved processability, versatility, and cost-effectiveness ( Grewal et al, 2018 ). Specifically, GO possesses interesting properties such as high hydrophilicity, solubility in water, large surface area, excellent dispersibility, and biocompatibility, making it an attractive material for various applications in fields such as energy storage ( Safari and Mazloom, 2023 ), biosensors ( Kadhim et al, 2023 ), water purification ( Tene et al, 2022a ), electronic devices ( Wu et al, 2023 ), and drug delivery ( Sontakke et al, 2023 ).…”

Section: Introductionmentioning

confidence: 99%

Optical properties of graphene oxide

et al. 2023

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The study of the optical properties of graphene oxide (GO) is crucial in designing functionalized GO materials with specific optical properties for various applications such as (bio) sensors, optoelectronics, and energy storage. The present work aims to investigate the electronic transitions, optical bandgap, and absorption coefficient of GO under different conditions. Specifically, the study examines the effects of drying times ranging from 0 to 120 h while maintaining a fixed temperature of 80°C and low temperatures ranging from 40℃ to 100℃, with a constant drying time of 24 h. Our findings indicate that exposing the GO sample to a drying time of up to 120 h at 80°C can lead to a reduction in the optical bandgap, decreasing it from 4.09 to 2.76 eV. The π−π* transition was found to be the most affected, shifting from approximately 230 nm at 0 h to 244 nm after 120 h of drying time. Absorption coefficients of 3140–5507 ml mg−1 m−1 were measured, which are similar to those reported for exfoliated graphene dispersions but up to two times higher, confirming the improved optical properties of GO. Our findings can provide insights into determining the optimal temperature and duration required for transforming GO into its reduced form for a specific application through extrapolation. The study is complemented by analyzing the elemental composition, surface morphology change, and electrical properties.

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Section: Introductionmentioning

confidence: 99%

Optical properties of graphene oxide

et al. 2023

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“…A clear understanding and interpretation of adsorption behavior at equilibrium is therefore a critical step in predicting the adsorption processes of diverse adsorption systems [ 37 ]. Here, linear Langmuir (Equation (6)) [ 38 ] and Freundlich (Equation (7)) [ 39 ] isotherm models were applied to fit the adsorption isotherm data for Cr(VI) adsorbed by GOs.

where Q e (mg/g) and Q m (mg/g) represent the adsorption capacity at equilibrium and at maximum, respectively; K L (L⋅mg −1 ) and K F ((mg⋅g −1 )⋅(L⋅mg −1 ) 1/n ) are Langmuir and Freundlich isotherm constants, respectively; and C e (mg/L) is the equilibrium concentration of the Cr(VI), n stands for adsorption intensity.…”

Section: Methodsmentioning

confidence: 99%

Structural Properties of Graphene Oxide Prepared from Graphite by Three Different Methods and the Effect on Removal of Cr(VI) from Aqueous Solution

et al. 2023

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Herein, three types of graphene oxides (GOs, GO-M1, GO-M2 and GO-M3) have been successfully prepared from graphite by three different methods and utilized for the removal of Cr(VI) from aqueous solutions. Further, the effects of initial concentration and pH, adsorbent dosage, contact time and temperature on the adsorption performance of GOs were investigated by batch adsorption experiments. Furthermore, the adsorption mechanisms for Cr(VI) adsorption by GOs are mainly the redox reaction and electrostatic attraction, while there are also pore filling, ion exchange and complexation involved in these adsorption processes. The adsorption kinetic and isotherm data indicate that these adsorption processes of GOs on Cr(VI) are dominantly monolayer chemisorption and equilibrium can be reached in 30 min. The saturation adsorption capacities (Qm, 298.15 K) of GO-M1, GO-M2 and GO-M3 for Cr(VI) are estimated to be 3.5412 mg×g−1, 2.3631 mg×g−1 and 7.0358 mg g−1, respectively. Moreover, the adsorption thermodynamic study showed that these adsorption processes of Cr(VI) by the three types of GOs at 298.15 K to 323.15 K are endothermic, entropy-driven and thermodynamically spontaneous and feasible. Overall, these findings provided vital insights into the mechanism and application of Cr(VI) removal by GOs.

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“…On the other hand, the physical and chemical characteristics of GO and rGO are significantly influenced by the oxidation method [11][12][13] as well as the reducing agent (e.g., hydrazine, ascorbic acid, and citric acid [14][15][16]). Indeed, there are different levels of oxidation or reduction as a result of these processes.…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Optical Properties of Oxidized Graphenes

Tene,

Vinueza-Naranjo,

Cevallos

et al. 2023

Nanomaterials

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In this study, we investigate how changing important synthesis-related parameters can affect and control the optical characteristics of graphene oxide (GO) and reduced graphene oxide (rGO). These parameters include drying time and reduction time at two different temperatures. We obtain an understanding of their impact on optical transitions, optical bandgap, absorption coefficient, and absorbance spectrum width by analyzing these factors. Accordingly, GO has an optical bandgap of about 4 eV, which is decreased by the reduction process to 1.9 eV. Both GO and rGO display greater absorption in the visible spectrum, which improves photon capture and boosts efficiency in energy conversion applications. Additionally, our results show that GO and rGO have higher absorption coefficients than those previously reported for dispersions of exfoliated graphene. Defects in GO and rGO, as well as the presence of functional oxygen groups, are the main contributors to this increased absorption. Several measurements are carried out, including spectroscopic and morphological studies, to further support our findings.

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Adsorption of Mercury on Oxidized Graphenes

Cited by 15 publications

References 59 publications

Optical properties of graphene oxide

Optical properties of graphene oxide

Structural Properties of Graphene Oxide Prepared from Graphite by Three Different Methods and the Effect on Removal of Cr(VI) from Aqueous Solution

Temperature-Dependent Optical Properties of Oxidized Graphenes

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