Expression of concern for 'Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes' by Sanny Verma , , 2011, , 12673-12675, https://doi.org/10.1039/C1CC15230K.
View Article and Find Full Text PDFHexavalent chromium oxyanions, known as potentially toxic micropollutants, exist in the effluents and discharges of metallurgical, electroplating, refractory, chemical, and tanning industries. The exposure of chromium-contaminated water causes severe health hazards. The present work outlines a facile approach to grow polyaniline (PANI) on fruit-waste-derived cellulose (CEL) via oxidative polymerization of aniline; followed by chemical processing with NHOH to obtain CEL-PANI-EB composites for adsorptive separation-coupled reduction of highly toxic hexavalent chromium oxyanions.
View Article and Find Full Text PDFA sustainable management of carcinogenic polycyclic aromatic hydrocarbons (PAHs) to synthesize a series of high surface area (SA of 563-1553 m g) microporous polymeric adsorbents is reported. The products with high yield (>90%) were obtained within only 30 min at a low temperature of 50 °C using a microwave-assisted approach with 400 W microwave power followed by 30 min of ageing by raising the temperature to 80 °C. The synthesized adsorbents are used for removing another category of carcinogenic pollutants i.
View Article and Find Full Text PDFPresent work addresses the synthesis of microporous activated carbon (SDAC) by a facile thermochemical conversion of teak sawdust powder. The high surface area (1999 m g), excellent microporosity (average pore size: 2.62 nm), and turbostratic carbon structure with intertwined graphitic domains make SDAC a highly efficient adsorptive material for the removal of organic pollutants.
View Article and Find Full Text PDFTungsten disulfide (WS) exhibits intriguing tribological properties and has been explored as an excellent lubricious material in thin-film and solid lubricants. However, the poor dispersibility of WS has been a major challenge for its utilization in liquid lubricant applications. Herein, a top-down integrated approach is presented to synthesize oxygenated WS (WS-O) nanosheets strong acid-mediated oxidation and ultrasound-assisted exfoliation.
View Article and Find Full Text PDFA wide range of organic pollutants in industrial effluents, agricultural runoff, and domestic discharges are exacerbating water scarcity, leading to water-borne ailments, and adversely affecting the marine ecosystem and biodiversity. The efficient, sustainable, and cost-effective materials need to be addressed urgently for the removal of organic pollutants. Herein, ultra-light (0.
View Article and Find Full Text PDFA facile approach is presented to synthesize the ionic liquid-grafted graphene oxide (GO-ImOH) for fast and efficient adsorptive removal of cationic dyes. A coupling reaction between the hydroxyl terminal of imidazolium ionic liquid and the carboxylic group of GO, yielded the GO-ImOH hybrid material. The higher surface negative charge (-32 mV) and excellent dispersibility make the GO-ImOH an efficient adsorbent for cationic dyes.
View Article and Find Full Text PDFACS Appl Mater Interfaces
November 2020
The present investigation demonstrates a green and scalable chemical approach to prepare aminoborate-functionalized reduced graphene oxide (rGO-AmB) for aqueous lubricants. The chemical, structural, crystalline, and morphological features of rGO-AmB are probed by XPS, FTIR, Raman, XRD, and HRTEM measurements. The spectroscopic analyses revealed the multiple interaction pathways between rGO and AmB.
View Article and Find Full Text PDFAdv Colloid Interface Sci
September 2020
Graphene, the most promising material of the decade, has attracted immense interest in a diversified range of applications. The weak van der Waals interaction between adjacent atomic-thick lamellae, excellent mechanical strength, remarkable thermal conductivity, and high surface area, make graphene a potential candidate for tribological applications. However, the use of graphene as an additive to liquid lubricants has been a major challenge because of poor dispersibility.
View Article and Find Full Text PDFIncommensurate stacking between two different types of two-dimensional layered materials furnished the weak interfacial interaction due to the mismatch of their lattice structure, which can be harnessed for development of new generation lubricant additives. Herein, a facile approach is presented to synthesize the ZnO-decorated reduced graphene oxide/MoS (Gr-MS-Zn) nanosheets. The Fourier transform infrared, X-ray photoelectron spectroscopic, Raman, and transmission electron microscopic analyses confirmed the preparation of Gr-MS-Zn heterostructure.
View Article and Find Full Text PDFTwo-dimensional transition-metal dichalcogenides possess inherent structural characteristics that can be harnessed for enhancement of tribological properties by making them dispersible in lube media. Here, we present a hydrothermal approach to preparing MoS nanosheets comprising 4-10 molecular lamellae. A structural-defect-mediated route for grafting of octadecylamine (ODA) on MoS nanosheets is outlined.
View Article and Find Full Text PDFMetal oxide nanomaterials and their composites are comprehensively reviewed for water remediation. The controlled morphological and textural features, variable surface chemistry, high surface area, specific crystalline nature, and abundant availability make the nanostructured metal oxides and their composites highly selective materials for efficient removal of organic pollutants based on adsorption and photocatalytic degradation. A wide range of metal oxides like iron oxides, magnesium oxide, titanium oxides, zinc oxides, tungsten oxides, copper oxides, metal oxides composites, and graphene-metal oxides composites having variable structural, crystalline and morphological features are reviewed emphasizing the recent development, challenges, and opportunities for adsorptive removal and photocatalytic degradation of organic pollutants viz.
View Article and Find Full Text PDFAlkylated graphene oxide (GO)/reduced graphene oxide (rGO) are prepared by covalent interaction with octadecyltrichlorosilane (OTCS) and octadecyltriethoxysilane (OTES). The variable oxygen functionalities in the GO/rGO and hydrolysis rate of octadecylsilanes having different leaving groups viz. trichloro and triethoxy found to govern the grafting density of octadecyl chains on the GO and rGO.
View Article and Find Full Text PDFShear-induced transfer of graphene on the contact interfaces was studied by microscopic and spectroscopic analyses of steel balls lubricated with chemically functionalized graphene-based mineral lube base oil (SN-150). The 3,5-di-tert-butyl-4-hydroxybenzaldehyde (DtBHBA) grafted-graphene (Gr-DtBHBA) was prepared by two-steps approach using graphene oxide as a precursor. Chemical and structural features of Gr-DtBHBA are probed by FTIR, XPS, Raman, TGA, and HRTEM analyses.
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2017
Efficient removal of malachite green (MG) dye from simulated wastewater is demonstrated using high surface area reduced graphene oxide (rGO). The plausible interaction pathways between MG dye and rGO are deduced from nanostructural features (HRTEM) of rGO and spectroscopic analyses (FTIR and Raman). The high surface area (931m⋅gm) of rGO, π-π interaction between the aromatic rings of MG dye and graphitic skeleton, and electrostatic interaction of cationic centre of MG dye with π-electron clouds and negatively charged residual oxygen functionalities of rGO collectively facilitate the adsorption of MG dye on the rGO.
View Article and Find Full Text PDFThe alkyl chain length of trioctylalkylammonium bis(salicylato)borates (N888n-BScB; n = 6, 8, 10 and 12) was varied to prepare a series of room-temperature ionic liquids, and then their viscosity and rheological properties were investigated. Besides the omnipresent Coulombic interactions, other interactive forces such as van der Waals interactions, hydrogen bonding, inductive forces, dipole-dipole interactions, etc., collectively determine the physicochemical properties of N888n-BScB ionic liquids.
View Article and Find Full Text PDFHexagonal boron nitride nanoplatelets (h-BNNPs), which are structurally analogous to graphene, were prepared via the ultrasound-assisted exfoliation of h-BN powder using N-methyl pyrrolidone as the solvent. The alkylamines with variable alkyl chains and electron-rich nitrogen atoms were grafted onto the boron sites of the h-BNNPs based on Lewis acid-base chemistry. The grafting of the alkylamines onto the h-BNNPs was confirmed using FTIR, XPS, TGA and (13)C SSNMR analyses.
View Article and Find Full Text PDFThin films of imidazolium (Im) ionic liquids with bis(salicylato)borate (BScB) and hexafluorophosphate (PF ) anions were grafted onto copper oxide (CuO) nanorods. Chemical and structural features of ionic-liquid-functionalized CuO (CuO-IL) nanorods were examined by X-ray photoelectron spectroscopy, FTIR spectroscopy, XRD, and high-resolution TEM analyses. The CuO-IL nanorods were demonstrated to be efficient photocatalysts for the splitting of water under visible-light irradiation without using any sacrificial agent.
View Article and Find Full Text PDFn-Alkylamines were grafted on the basal plane oxygen functionalities of graphene oxide (GO), yielding molecular pillar supported graphene oxide frameworks (GOFs) with tunable interlayer spacing. A major fraction of n-alkylamines was found to covalently interact with the basal plane epoxy groups via nucleophilic substitution reactions. The d-spacing in GOFs could be tailored between 10.
View Article and Find Full Text PDFHexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs.
View Article and Find Full Text PDFThe octahedral molybdenum cluster-based compound, Cs2 Mo6 Br(i) 8 Br(a) 6 was immobilized on graphene oxide (GO) by using a facile approach. High resolution transmission electron microscopy results revealed that molybdenum clusters were uniformly distributed on the GO nanosheets. Cs2 Mo6 Br(i) 8 Br(a) 6 was attached to the GO support via chemical interaction between apical ligands of Mo6 Br(i) 8 Br(a) 6 cluster units and oxygen functionalities of GO, as revealed by XPS studies.
View Article and Find Full Text PDFBis(imidazolium)- and bis(ammonium)-di[bis(salicylato)borate] ionic liquids with variable alkyl chain and cyclic ring structures, were synthesized and then evaluated them as potential lubricant additives. The copper strip test results revealed noncorrosive properties of these ionic liquids. Introduction of halogen content in bis(imidazolium) ionic liquid by replacement of bis(salicylato)borate (BScB) anion with hexafluorophosphate (PF6(-)), severely corroded the copper strip.
View Article and Find Full Text PDFA rhenium-oxo complex such as methyltrioxorhenium (MTO) has been homogeneously immobilized on a Schiff base modified graphene oxide (GrO) support via covalent bonding. The loading of MTO on GrO nanosheets was monitored by FTIR, TG-DTA, and elemental analyses. The developed heterogeneous catalyst is found to be efficient for the oxidation of various amines to the corresponding N-oxides using hydrogen peroxide as an oxidant in high to excellent yields.
View Article and Find Full Text PDFA green and facile approach for the partial deoxygenation of graphene oxide (GO) at moderate temperature (100 °C) and under atmospheric pressure, catalyzed by acidic conditions in water is reported. The chemical and structural changes in GO as a function of hydrothermal time were probed to understand the deoxygenation events. The brown GO dispersion in water was found to gradually turn black over the hydrothermal-treatment time on account of the increasing graphitic content.
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2012
Synthesis of ω-alkenyl-terminated silver nanoparticles (AgNPs) and then their immobilization on a hydrogen-terminated silicon surface in two-dimensional arrangement through covalent interaction are demonstrated. The thermal-induced hydrosilylation at mild conditions facilitate nanoparticles assembly through interaction between terminal alkenyl (CH(2)=CH-) groups of AgNPs and hydrogen-terminated silicon surface. The assembly of AgNPs on a silicon surface is characterized by FESEM and XPS.
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