Catalytic hydrogenation reduction based on sodium borohydride (NaBH
) has gained attention as an appealing "one-stone-two-birds" approach for the simultaneous elimination of nitroaromatic pollutants ...and the production of high-value aminoaromatics under mild conditions. However, the slow kinetics of NaBH
dissociation on the surface of catalysts restrict the catalytic hydrogenation reduction efficiency. Herein, we report an intelligent localized sulfidation strategy for an in situ implantation of Bi
S
nanorods within quasi-Bi-MOF architectures (Bi
S
@quasi-Bi-MOF) by fine-tuning the pyrolysis temperature. In this novel Bi
S
@quasi-Bi-MOF, the porous quasi-Bi-MOF enables efficient adsorption of BH
and 4-nitrophenol (4-NP), while Bi
S
facilitates the BH
dissociation to form H
* species adsorbed on the catalyst surface. Benefiting from the synergistic structure, Bi
S
@quasi-Bi-MOF exhibits excellent performance for the catalytic reduction of 4-NP, delivering a high turnover frequency (TOF) of 1.67 × 10
mmol mg
min
and an extremely high normalized rate constant (
) of 435298 s
g
. The kinetic analysis and electrochemical tests indicate that this catalytic hydrogenation reduction follows the Langmuir-Hinshelwood mechanism. This study enriches the synthetic strategy of MOF-based derivatives and offers a new catalytic platform for hydrogenation reduction reactions.
The conversion of organic pollutants to value-added chemicals has been considered as a sustainable approach to solve environmental problems. However, it is still a challenge to construct a suitable ...heterogeneous catalyst that can synchronously achieve the enrichment and activation of organic pollutants (such as 4-nitrophenol, 4-NP). Here, an organic-inorganic hybrid catalyst (CeO
/Ni-MOF) was successfully fabricated for efficiently reducing 4-NP to 4-aminophenol (4-AP) with water as the hydrogen source. Based on the synergistic effect of Ni-MOF (adsorption action) and CeO
(active sites), CeO
/Ni-MOF could achieve a reaction rate of 1.102 μmol min
mg
with an ultrahigh Faraday efficiency (FE) (99.9%) and conversion (97.6%). In addition, the catalytic mechanism of 4-NP reduction over CeO
/Ni-MOF was elaborated in depth. This work presents a new avenue for the effective reduction of pollutants and provides a new strategy for designing high-performance catalysts for rare-earth metals.
Three new triazine compounds Co1.5(H3TDPAT)(H2O)3·6H2O (1), Co2(TCPT)(μ2-H2O)2·OH (2), and Ni3(TCPT)·3OH (3) were designed and synthesized via the reaction of the symmetrical triazine ligand ...connected by C–N–C and C–O–C bonds with triazine poly(carboxylic acid)s ligands as the side arms: H6TDPAT (H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) and H3TCPT (H3TCPT = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine) as well as the corresponding metal salts under the solvothermal condition. Three triazine polycarboxylate frameworks were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and solid fluorescent spectra in detail. The structural analysis results showed that the three-dimensional porous cage framework of compound 1 was constructed by three different polyhedral cages connected with Co(COO)4(H2O)2 building blocks. One of the compounds, 2, is formed by twin propeller Co2(μ2-H2O)(COO)3 building blocks connecting two-dimensional layers and the intermolecular π–π interactions involved the triazine rings between the layers. While the structure of compound 3 is similar to that of 2, assembly is by Ni(COO)3 building blocks and adjacent layers of the face-to-face π–π interaction between the triazine rings. In order to explore functional properties, the catalytic reduction of p-nitrophenol (PNP) of compounds 1–3 was investigated. They exhibit excellent catalytic activity of more than 95% for reduction of PNP with a dose of 2.5 mg of the compounds.
Generally, the catalytic transformation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at heterogeneous metal surfaces follows a Langmuir-Hinshelwood (L-H) mechanism when sodium borohydride (NaBH
) ...is used as the sacrificial reductant. Herein, with Pt-Ag bimetallic nanoparticles confined in dendritic mesoporous silica nanospheres (DMSNs) as a model catalyst, we demonstrated that the conversion of 4-NP did not pass through the direct hydrogen transfer route with the hydride equivalents being supplied by borohydride
the bimolecular L-H mechanism, since Fourier transform infrared (FTIR) spectroscopy with the use of isotopically labeled reactants (NaBD
and D
O) showed that the final product of 4-AP was composed of protons (or deuterons) that originated from the solvent water (or heavy water). Combined characterization by X-ray photoelectron spectroscopy (XPS),
H nuclear magnetic resonance (NMR) and the optical excitation and photoluminescence spectrum evidenced that the surface hydrous hydroxide complex bound to the metal surface (also called structural water molecules, SWs), due to the space overlap of p orbitals of two O atoms in SWs, could form an ensemble of dynamic interface transient states, which provided the alternative electron and proton transfer channels for selective transformation of 4-NP. The cationic Pt species in the Ag-Pt bimetallic catalyst mainly acts as a dynamic adsorption center to temporally anchor SWs and related reactants, and not as the active site for hydrogen activation.
A highly sensitive and selective fluorescent biosensor has been exploited for the determination of p-NP and ALP activity based on the GSH-CuNCs mediated-inner filter effect.
Display omitted
•The ...IFE-based strategy can eliminate environmental interference and background noises efficiently.•The GSH-CuNCs were facilely prepared and without any other complicated separation process.•This strategy was free of any fluorescence dye label and other complex design.•The IFE-based method had a much higher sensitivity and selectivity compared with the traditional fluorescent assay.
A simple and highly selective fluorescence biosensor has been exploited for p-nitrophenol (p-NP) and alkaline phosphatase (ALP) activity detection based on the glutathione-stabilized copper nanoclusters (GSH-CuNCs) mediated-inner filter effect (IFE). The GSH-CuNCs were prepared by employing GSH as stabilizer and ascorbic acid (AA) as reductant. The obtained GSH-CuNCs exhibited a strong blue fluorescence emission at 420 nm with an excitation wavelength of 365 nm, which overlapped largely with the absorption spectra of p-nitrophenol (p-NP). Therefore, the luminescence of GSH-CuNCs could be quenched by p-NP through inner filter effect. In addition, ALP catalyzed the substrate p-nitrophenyl phosphate (p-NPP) to form p-nitrophenol (p-NP), which also leading to the fluorescence quenching of GSH-CuNCs. The fluorescent strategy was realized for the sensitive determination of p-NP and ALP activity with the promising limit of detection of 20 nM (for p-NP) and 0.003 mU⋅mL−1 (for ALP). Furthermore, the method could be applied to detect the p-NP content in river water samples and ALP activity in human serum samples.
An efficient green method of gold nanoparticles (AuNPs) biosynthesis was achieved by cell-free extracts of fungus Trichoderma sp. WL-Go. Based on UV–Vis spectra, AuNPs biosynthesised by cell-free ...extracts with 90 mg/l protein exhibited a characteristic absorption band at 556 nm and was stable for 7 days. Transmission electron microscopy images revealed that the as-synthesised AuNPs were spherical and pseudo-spherical, and the average size was calculated to be 9.8 nm with a size range of 1–24 nm. The AuNPs illustrated their good catalytic activities for reduction of nitro-aromatics (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-nitroaniline, 3-nitroaniline) with catalytic rate constants of 7.4 × 10−3 s−1, 10.3 × 10−3 s−1, 4.9 × 10−3 s−1, 5.8 × 10−3 s−1, 15.0 × 10−3 s−1, respectively. Meanwhile, the AuNPs also showed excellent catalytic performance in decolourisation of azo dyes with decolourisation efficiency from 82.2 to 97.5%. This study provided a green gentle method for AuNPs synthesis as well as exhibiting efficient catalytic capability for degradation of aromatic pollutants.
Ceria (CeO2) is an exciting alternative noble metal catalyst, because it has ability to release and absorb oxygen in the redox system, and function as an oxygen buffer. In this study, ...heterostructured catalysts consisting of CeO2/Y2O3 nanocomposites were successfully synthesized by hydrothermal method in the presence of sodium hydroxide as a reducing agent from cerium nitrate and yttrium nitrate as a precursor which was then evaluated for its photocatalytic activity in the degradation of Rhodamine B (RhB) synthetic dye. Scanning electron microscopy (SEM) imparts the surface morphology and size of the prepared sample. Elemental compositions and the purity of the nanoparticles are proved by energy dispersive X-ray Spectroscopy (EDX). CeO2/Y2O3 nanoparticles were made up of CeO and YO bonds which are confirmed by Fourier transform infrared spectroscopy (FTIR). Synthesis temperature and pressure, during hydrothermal reactions, plays a critical role in controlling the shape, size, oxygen vacancy concentration, and low temperature reducibility in CeO2 based nanocomposites. The lattice constants and oxygen vacancy concentrations of ceria nanoparticles also depend upon the concentration of hydroxide ion which leads to better morphology at low temperature and pressure. Hydrogenation of p-nitrophenol to p-aminophenol with a reducing agent is conveniently carried out in aqueous medium by using this binary metal oxide catalyst. Further, the photocatalytic performance of the synthesized nanoparticles was monitored by photocatalytic degradation of Rhodamine B synthetic dye under UV light irradiation. To get maximum photocatalytic degradation (PCD) efficiency, we have used H2O2 for the generation of excess reactive oxygen species (ROS). In addition, the antibacterial activity of nanoparticles against bacteria was also examined. The observed antibacterial activity results are comparable with the results obtained using the standard antibiotic.
Display omitted
•CeO2/Y2O3 nanocomposites were successfully synthesized by hydrothermal method.•H2O2 for the generation of excess reactive oxygen species (ROS)•Hydrogenation of p-nitrophenol to p-aminophenol with a reducing agent•Specifically lattice planes associated with cubic CeO2 can be observed with SAED.•Observed antibacterial results are comparable with the standard antibiotic activity.
A waste-treats-waste approach has been used for the removal of two common pollutants, namely p-nitrophenol and/or Fe(III) from aqueous solution. Polyethyleneterephthalate (PET) from bottle waste has ...been used as the precursor for the preparation of activated carbons (ACs) by physical activation with steam and chemical activation with potassium hydroxide under controlled heating conditions and atmospheres. The resulting ACs were characterized in terms of chemical composition, porous texture and surface chemistry, and morphology. Selected ACs were tested as adsorbents for the removal of the aforementioned pollutants in aqueous solution. For comparison purposes, a commercial AC was also used. In general, the yield of the process of preparation of ACs is lower than 10% with steam and between 24.62 and 32.07% with potassium hydroxide. ACs possess a very high carbon content and a very low ash content. The BET surface areas reach 1235 m2 g−1 with steam and 1002 m2 g−1 with potassium hydroxide at most. Also, the degrees of development of micro- and mesoporosity are markedly larger with steam. Conversely, the development of macroporosity is much larger with potassium hydroxide. The PET-derived ACs exhibit a better adsorption behavior towards p-nitrophenol than the commercial AC, both in terms of adsorption rate and adsorption capacity. On the contrary, the commercial AC acts as a better adsorbent of Fe(III) ions. As compared to separately, the simultaneous presence of both solutes in the adsorptive solution scarcely affects the adsorption process except for equilibrium for Fe(III).
•PET by its chemical composition is suitable for activated carbon (AC) preparation.•Obtained ACs exhibit high development of surface area and porosity.•Such ACs behave as better adsorbents of p-nitrophenol (PNP) than a commercial one.•Fe(III) and PNP scarcely interfere with each other in terms of adsorption kinetics.•The effect of PNP on the adsorption equilibrium for Fe(III) is remarkable.
Generation of environmentally persistent free radicals (EPFRs) on solid particles has recently attracted increasing research interest. EPFRs potentially have high reactivity and toxicity. However, ...the impact of EPFRs on organic contaminant behavior is unclear. We hypothesized that EPFRs in biochars can degrade organic contaminants and play an important role in organic contaminant behavior. We observed obvious degradation of p-nitrophenol (PNP) in the presence of biochars, through the detection of NO3 – as well as organic byproducts. The extent of PNP degradation was correlated to the intensity of EPR signals of biochar particles. tert-Butanol (a •OH scavenger) did not completely inhibit PNP degradation, indicating that •OH could not fully explain PNP degradation. The decreased PNP degradation after tert-butanol addition was better correlated with reduced PNP sorption on biochars. PNP degradation through the direct contact with EPFRs in biochar particles could be an important contribution to the PNP concentration reduction in the aqueous phase. The coating of natural organic matter analogue (tannic acid) on biochars did not considerably inhibit PNP degradation, suggesting the ability of biochars to degrade PNP in soil and natural water. Similar EPFR-promoted degradation was observed for five different types of biochars and one activated carbon, as well as one additional chemical (p-aminophenol). Therefore, organic chemical degradation by EPFRs in biochars can be a common process in the environment and should be incorporated in organic chemical fate and risk studies.
Nitrobenzene compounds are highly toxic pollutants with good stability, and they have a major negative impact on both human health and the ecological environment. Herein, it was found for the first ...time that fluorescent DNA-silver nanoclusters (DNA-AgNCs) can catalyze the reduction of toxic and harmful nitro compounds into less toxic amino compounds with excellent tolerance to high temperature and organic solvents. In this study, the reduction of p-nitrophenol (4-NP) as a model was systematically investigated, followed by expending the substrate to disclose the versatility of this reaction. This report not only expanded the conditions for utilizing catalytic reduction conditions of DNA-AgNCs as an efficient catalyst in the control of hazardous chemicals but also widened the substrate range of DNA-AgNCs reduction, providing a new angle for the application of noble metal nanoclusters.
PDF
