Graphene nanoplates (GNPs) can be used as a platform for homogeneous distribution of adsorbent nanoparticles to improve electron exchange and ion transport for heavy-metal adsorption. In this study, ...we report a facile thermal decomposition route to fabricate a graphene-supported Fe–Mg oxide composite. The prepared composite was characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Batch experiments were carried out to evaluate the arsenic adsorption behavior of the GNP/Fe–Mg oxide composite. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, in which the sorption kinetics of the arsenic adsorption process by the composite was found to be pseudo-second-order. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled-column filter test. The GNP/Fe–Mg oxide composite exhibited significant fast adsorption of arsenic over a wide range of solution pHs, with exceptional durability and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solutions.
•Porphyrin nanomaterials exhibiting photocatalytic activity were synthesized.•The physicochemical properties of the synthesized nanomaterials were evaluated.•The effect of the H2O fraction on the ...assembly process and morphology was explored.•The nanomaterials exhibited high photocatalytic activity under visible light.•A mechanism for the photocatalytic activity of the nanomaterials was proposed.
Porphyrin aggregates formed via self-assembly have shown promising photocatalytic activity due to the combination of their optical and morphological properties. The structural and physical properties of porphyrin affect its self-assembly and the properties of the resulting aggregates. The hydrophobicity/hydrophilicity of the porphyrins in solvent mixtures, which affect self-assembly, can be altered by the introduction of fluorine groups. In this work, we report the synthesis of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPFPP). The differing solubilities of TPFPP in organic and aqueous solutions were exploited to promote the self-assembly of monomeric TPFPP in THF/H2O solvent mixtures. The effect of the H2O fraction on the assembly process and resulting morphologies was probed using UV–vis spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy (SEM). It was observed that well-defined TPFPP microrods with a diameter of 1–3 µm and length of 20–100 µm as well as octahedral crystals 30 µm in size were produced with H2O fractions of 70 and 80%, respectively. These TPFPP aggregates with controlled morphologies exhibited high photocatalytic activity, evident in photocatalytic degradation studies with rhodamine B (RhB) which degraded under visible light irradiation with rate constants of 3.76 × 10−3 (with microrods) and 2.93 × 10−3 min−1 (with octahedral crystals). A possible mechanism for the photocatalytic activity of the TPFPP aggregates for RhB degradation was proposed.
In this communication, we have investigated the arginine-induced fabrication of porphyrin (TCPP)-based supramolecular nanostructures. These self-assembled porphyrin nanostructures such as nanobelts ...show enhanced photocatalytic activity for the photodegradation of pollutant Rhodamine B under simulated visible-light irradiation.
Chalcopyrite ore was roasted at 200, 550 and 800°C in reducing (5%H2/95%Ar) and inert (N2) atmospheres to examine the effects of the thermal pre-treatment on the phase mineralogy and on subsequent ...copper extraction using sulfuric acid media. No mineralogical changes occurred in the pre-leached samples heated to 200°C under both inert and reducing conditions while at 550°C partial decomposition of chalcopyrite resulted forming bornite and metal-rich derivatives talnakhite and mooihoekite. Further heating to 800°C saw differences in chalcopyrite decomposition according to the atmosphere. In the inert atmosphere chalcopyrite decomposed to the metal-rich derivatives and minor bornite and geerite while in the reduced atmosphere copper metal, bornite, troilite, cubanite and chalcocite formed. Leaching at 50°C of the chalcopyrite pre-treated in an inert atmosphere saw a slight increase in %Cu extraction with increasing temperature of treatment. A maximum copper extraction of 16%Cu was measured in the sample treated at 800°C. Leaching of the chalcopyrite pre-treated in a reduced atmosphere led to modest increases in copper extraction between the 200°C and 550°C samples with 21%Cu and 24%Cu leached. Treatment at 800°C resulted in a significant increase reaching 78%Cu extraction.
•Impact of reducing and inert thermal pre-treatment on Chalcopyrite•Structural and chemical modifications due to thermal pre-treatment•Sulfuric acid leaching of pre-treated Chalcopyrite
Scientists are often inspired by nature, where naturally occurring morphologies, such as those that resemble animals and plants, can be created in the lab. In this review, we have provided an ...overview on complex superstructures of animals, plants and some similar shapes from the natural world. We begin this review with a discussion about the formation of various animal‐like shapes from small organic molecules and polymers, and then move onto plants and other selected shapes. Literature surveys reveal that most of the polymers studied tend to form micellar structures, with some exceptions. Nevertheless, small organic molecules tend to form not only micellar structures but also other animal shapes such as worms and caterpillars. These superstructures tend to have high surface areas and variable surface morphology, making them very useful material for applications in various field such as catalysis, solar cells, and biomedicine, amongst others.
In this review various mimicking of natural shapes have been discussed via supramolecular self‐assembly by using small organic molecules have been explained. The review starts with the shapes from molecular structures and deviation from crystal growth followed by superstructure shape and their origin, and hierarchical self‐assembled superstructure shapes. We concluded our review with future prospective in the development and utilisation of natural mimicking structures for various applications.
Gold compounds activate alkynes for palladium coupling reactions acting as efficient co-calalysts in Sonogashira reaction in THF and water.
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A series of inorganic and organometallic compounds of ...gold AuCl(tht), Au(C
6F
5)(tht) and NaAuCl
4 (tht
=
tetrahydrothiophene) are shown to efficiently co-catalyze the Sonogashira-type cross-coupling reaction of phenylacetylene with aryl halides in THF solution. AuCl(tppts) (tppts
=
trisodium salt of tris(
m-sulfonatophenyl)phosphine) co-catalyzes the same reaction in biphasic aqueous systems. Gold compounds are thus revealed as efficient transmetalation catalysts to palladium.
Au nanoparticles on an Fe-based support.
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A strategy is described for the direct preparation of Au nanoparticles (AuNPs) on a Fe-based support, coated with porous carbon (PC), via ...pyrolysis of an AuCN functionalised Prussian Blue (PB) metal organic framework (MOF). The composite starting material was prepared with an even distribution of AuCN on the surface via galvanic exchange of PB with a gold salt in solution. The resulting structures after pyrolysis were shown to be active Au-based nanomaterials for model applications including catalysis (4-nitrophenol reduction) and electroanalysis (arsenic (III) detection), suggesting broad application where Au nanoparticles are required at a liquid-solid interface. The Fe based support was seen to consist of Fe, Fe3C and Fe4C phases, and the carbon coating increased the stability and improved the conductivity of the materials. The temperature of pyrolysis was seen to affect the activity of the supported nanoparticles, with an increased Au surface area obtained at the higher pyrolysis temperature (650 °C) tested. A general strategy is thus confirmed for preparation of noble metal nanoparticles evenly distributed on a magnetic support, allowing easy separation of catalysts from products in heterogeneous applications.
Microelectromechanical sensors based on surface acoustic wave (SAW) and quartz crystal microbalance (QCM) transducers possess substantial potential as online elemental mercury (Hg(0)) vapor detectors ...in industrial stack effluents. In this study, a comparison of SAW- and QCM-based sensors is performed for the detection of low concentrations of Hg(0) vapor (ranging from 24 to 365 ppbv). Experimental measurements and finite element method (FEM) simulations allow the comparison of these sensors with regard to their sensitivity, sorption and desorption characteristics, and response time following Hg(0) vapor exposure at various operating temperatures ranging from 35 to 75 °C. Both of the sensors were fabricated on quartz substrates (ST and AT cut quartz for SAW and QCM devices, respectively) and employed thin gold (Au) layers as the electrodes. The SAW-based sensor exhibited up to ∼111 and ∼39 times higher response magnitudes than did the QCM-based sensor at 35 and 55 °C, respectively, when exposed to Hg(0) vapor concentrations ranging from 24 to 365 ppbv. The Hg(0) sorption and desorption calibration curves of both sensors were found to fit well with the Langmuir extension isotherm at different operating temperatures. Furthermore, the Hg(0) sorption and desorption rate demonstrated by the SAW-based sensor was found to decrease as the operating temperature increased, while the opposite trend was observed for the QCM-based sensor. However, the SAW-based sensor reached the maximum Hg(0) sorption rate faster than the QCM-based sensor regardless of operating temperature, whereas both sensors showed similar response times (t90) at various temperatures. Additionally, the sorption rate data was utilized in this study in order to obtain a faster response time from the sensor upon exposure to Hg(0) vapor. Furthermore, comparative analysis of the developed sensors' selectivity showed that the SAW-based sensor had a higher overall selectivity (90%) than did the QCM counterpart (84%) while Hg(0) vapor was measured in the presence of ammonia (NH3), humidity, and a number of volatile organic compounds at the chosen operating temperature of 55 °C.
A charge-transfer (CT) complex self-assembled from an electron acceptor (NDI-EA: naphthalene diimide with appended diamine) and an electron donor (DAN: phosphonic acid-appended dialkoxynapthalene) in ...aqueous medium. The aromatic core of the NDI and the structure of DAN1 were designed to optimize the dispersive interactions (π-π and van der Waals interactions) in the DAN1-NDI-EA self-assembly, while the amino groups of NDI also interact with the phosphonic acid of DAN1 via electrostatic forces. This arrangement prevented crystallization and favored the directional growth of 3D flower nanostructures. This molecular geometry that is necessary for charge transfer to occur was further evidenced by using a mismatching DAN2 structure. The flower-shaped assembly was visualized by scanning electron and transmission electron microscopy. The formation of the CT complex was determined by UV-vis and cyclic voltammetry and the photoinduced electron transfer to produce the radical ion pair was examined by femtosecond laser transient absorption spectroscopic measurements.
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