“…So, the glycerol molecules can attract easily and with high concentration to the catalyst GQD surface, forming a hydrogen bonding network with different sites. This hydrogen bond strongly tightens the glycerol on the catalyst surface either via a single hydrogen bond or chelated hydrogen bonding between two hydroxyl groups of glycerol with the surface-active sites on GQDs 48 . Figure 6 The pathway for the migration of electrons from the catalyst's surface during photocatalytic glycerol oxidation to the liquid product.…”
Nowadays, dealing with the growing chemical and energy demands is important without compromising the environment. So, this work studies photocatalytic glycerol conversion (as biomass derivativ feedstock) into value-added products using an eco-friendly synthesized catalyst. Graphene quantum dots (GQDs) were prepared from available/cheap precursors like glucose via the hydrothermal method and used as a support for TiO2. TiO2/GQDs were characterized via different analytical techniques, revealing very small particle sizes of ~ 3–6 nm with a large surface area of ~ 253 m2/g and a band gap of ~ 2.6 eV. The prepared photocatalyst shows good efficiency during photocatalytic glycerol conversion to dihydroxyacetone (DHA). Different reaction conditions were tested: reaction time, catalyst amount, presence of oxidant (H2O2), and biphasic media (aqueous/organic phases). Comparing a monophasic (H2O) photoreactor with a biphasic reactor containing 90% organic phase (ethyl acetate) and 10% aqueous phase (H2O and/or H2O2) indicates that the presence of H2O2 increases glycerol conversion and liquid selectivity to reach 57% and 91%, respectively after 120 min. However, it still suffers a low DHA/GA ratio (2.7). On the other hand, using a biphasic reactor in the presence of an H2O2 oxidant increases the DHA/GA ratio to ~ 6.6, which was not reached in previous research. The formation of H2O/H2O2 as micro-reactors dispersed in the ethyl acetate phase increased the average light intensity effect of the glycerol/photocatalyst system in the micro-reactors. Unlike previous work, this work presents a facile way to prepare eco-friendly/cheap (noble metal free) photocatalysts for glycerol conversion to ultrapure DHA using a biphasic photoreactor.
“…So, the glycerol molecules can attract easily and with high concentration to the catalyst GQD surface, forming a hydrogen bonding network with different sites. This hydrogen bond strongly tightens the glycerol on the catalyst surface either via a single hydrogen bond or chelated hydrogen bonding between two hydroxyl groups of glycerol with the surface-active sites on GQDs 48 . Figure 6 The pathway for the migration of electrons from the catalyst's surface during photocatalytic glycerol oxidation to the liquid product.…”
Nowadays, dealing with the growing chemical and energy demands is important without compromising the environment. So, this work studies photocatalytic glycerol conversion (as biomass derivativ feedstock) into value-added products using an eco-friendly synthesized catalyst. Graphene quantum dots (GQDs) were prepared from available/cheap precursors like glucose via the hydrothermal method and used as a support for TiO2. TiO2/GQDs were characterized via different analytical techniques, revealing very small particle sizes of ~ 3–6 nm with a large surface area of ~ 253 m2/g and a band gap of ~ 2.6 eV. The prepared photocatalyst shows good efficiency during photocatalytic glycerol conversion to dihydroxyacetone (DHA). Different reaction conditions were tested: reaction time, catalyst amount, presence of oxidant (H2O2), and biphasic media (aqueous/organic phases). Comparing a monophasic (H2O) photoreactor with a biphasic reactor containing 90% organic phase (ethyl acetate) and 10% aqueous phase (H2O and/or H2O2) indicates that the presence of H2O2 increases glycerol conversion and liquid selectivity to reach 57% and 91%, respectively after 120 min. However, it still suffers a low DHA/GA ratio (2.7). On the other hand, using a biphasic reactor in the presence of an H2O2 oxidant increases the DHA/GA ratio to ~ 6.6, which was not reached in previous research. The formation of H2O/H2O2 as micro-reactors dispersed in the ethyl acetate phase increased the average light intensity effect of the glycerol/photocatalyst system in the micro-reactors. Unlike previous work, this work presents a facile way to prepare eco-friendly/cheap (noble metal free) photocatalysts for glycerol conversion to ultrapure DHA using a biphasic photoreactor.
“…The d -spacings of 2:1-0-GOM, 2:1-100-GOM, 2:1-200-GOM, and 2:1-300-GOM were determined to be 8.8, 8.8, 8.9, and 9.1 Å, respectively. Presumably, the broader channel size is derived from the inserted glycerol, which could interact with oxygen functional groups via a hydrogen bond. , Although the channel size of the GO membranes does not dramatically increase depending on the stirring rate, the wrinkles and pores present in the layered structure can deteriorate on the membrane separation performance. In addition, the change of the channel size in a wet state was investigated, in which case, the interlayer spacing of the GO membranes is rather broadened as the water molecules are intercalated into the GO layers (Figure S8).…”
Two-dimensional (2D)
membranes enable ion-sieving through well-defined
subnanoscale channels. In particular, graphene oxide (GO), a representative
2D material with a flexible structure, can be manufactured into various
types of membranes, while defects such as pores and wrinkles are readily
formed through self-aggregation and self-folding during membrane fabrication.
Such defects provide a path for small ionic or molecular species to
be easily penetrated between the layers, which deteriorates membrane
performance. Here, we demonstrate the effect of shear-induced alignment
with continuous agitation on GO membrane structure during pressure-assisted
filtration. The shear stress exerted on the GO layers during deposition
is controlled by varying the agitation rate and solution viscosity.
The well-stacked 2D membrane is obtained via the facile shear-controlled
process, leading to an improved salt rejection performance without
additional physicochemical modifications. This simple approach can
be extensively utilized to prepare the well-ordered structure of other
2D materials in various fields where the defect control is required.
“…However, due to the difficult top-down synthesis, poor solubility, and agglomeration problem in solution, GO was synthesized from graphite using Hummers method through oxidation [ 129 ]. It has retained worthy attributes such as electrical and thermal conductivity, mechanical stiffness and biocompatible properties [ 130 ]. Additionally, remarkable mechanical properties were obtained from interfacial interaction of GO with polymer matrix by increasing the functional group of GO sheets to fabricate GO-derived nanocomposites as presented in Figure 10 .…”
Section: Graphene Impacts In Drilling Operationsmentioning
Nanocomposite materials have distinctive potential for various types of captivating usage in drilling fluids as a well-designed solution for the petroleum industry. Owing to the improvement of drilling fluids, it is of great importance to fabricate unique nanocomposites and advance their functionalities for amplification in base fluids. There is a rising interest in assembling nanocomposites for the progress of rheological and filtration properties. A series of drilling fluid formulations have been reported for graphene-derived nanocomposites as additives. Over the years, the emergence of these graphene-derived nanocomposites has been employed as a paradigm to formulate water-based drilling fluids (WBDF). Herein, we provide an overview of nanocomposites evolution as engineered materials for enhanced rheological attributes in drilling operations. We also demonstrate the state-of-the-art potential graphene-derived nanocomposites for enriched rheology and other significant properties in WBDF. This review could conceivably deliver the inspiration and pathways to produce novel fabrication of nanocomposites and the production of other graphenaceous materials grafted nanocomposites for the variety of drilling fluids.
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