In this paper, a new pair of nonself mappings is first introduced. And then, we study the stability and convergence rate of Jungck-type iterations for the mappings. Some numerical examples are also ...given to support the results. Our results generalize and improve some known results in the literature.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Recently, the natural polymer polysaccharide konjac glucomannan (KGM) has received attention as a promising adsorbent in water treatment due to its low toxicity, cost-effectiveness and ...biocompatibility. However, the high-level water absorbency of KGM makes it difficult to recover in water treatment. In this study, by combining KGM with magnetic nanoparticles, KGM-based magnetic nanoparticles (KGM-Fe3O4 NPs) with excellent adsorption properties and recyclability for heavy metals were prepared using an one-step precipitation method. The as-prepared KGM-Fe3O4 NPs have a spherical morphology of superparamagnetism with a small particle size (ca. 7.0 nm) and a large specific surface area (160.1 m2·g−1). Taking Cr(VI) as the target heavy metal ion, the above nanoparticles have a high adsorption capacity and fast adsorption rate for Cr(VI). The pseudo-second order kinetic model is more suitable to describe the adsorption process of Cr(VI) by KGM-Fe3O4 NPs, and the maximum adsorption capacity of Cr(VI) onto KGM-Fe3O4 NPs was calculated to be 41.67 mg·g−1 using the Langmuir isotherm model. In addition, KGM-Fe3O4 NPs with adsorbed heavy metal ions can be quickly recovered from a solution, regenerated, and reused in the next cycle. KGM-based Fe3O4 nanoparticles are promising adsorbents that show significant reusability for the removal of metal ions in water and wastewater treatment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
An efficient adsorbent for the treatment of Cr(VI) was simply fabricated by combining graphene oxide with MoS
2
nanosheets via in situ hydrothermal process with CTAB as the surfactant. The ...experimental results indicated that the agglomeration of the MoS
2
nanosheets are reduced and uniformly grown on the graphene sheet during the in situ hydrothermal process, and the introduction of graphene oxide provided higher specific surface area and abundant oxygenic groups. Based on this, the removal efficiency of Cr(VI) onto MoS
2
/rGO was 75.9% at pH 2.0, which was higher than that of bulk MoS
2
(61.0%). On account of Sips adsorption isotherm model, the highest uptake capacity of MoS
2
/rGO toward Cr(VI) reached 80.8 mg g
−1
. The adsorption kinetic consequences showed that the chemisorption process was the control step, and the removal mechanism for Cr(VI) is redox and adsorption; in this way, the adsorbed Cr(VI) was partially reduced to Cr(III). Furthermore, this as-prepared adsorbent also presented satisfying reusability for removal of Cr(VI) and can be used for the selective removal of Cr(VI) in the presence of NO
3
−
. In short, it may provide a potential route to enhance the adsorption property of MoS
2
toward heavy metals through incorporating with GO, which would expand the applications of MoS
2
in the field of treatment of the heavy metal wastewater.
Hydrogenation of ester levulinate to gamma-valerolactone (GVL) is an interesting reaction in biomass conversion to produce value-added chemicals. Exploration of efficient and robust catalysts is ...crucial for large-scale application. In this work, we conducted the reaction catalyzed by a Co catalyst, and it was found that commercially available Co sub(3)O sub(4) was very efficient for this reaction under mild conditions after reduction by H sub(2). The effects of temperature, hydrogen pressure, amount of the catalyst used, and reaction time on the yield of GVL were studied. Under optimized conditions, the yield of GVL could reach 98%. The catalyst could be reused at least 10 times without notable loss of the activity and selectivity. The catalyst was characterized by scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). It was demonstrated that the metallic Co super(0) was the active species for the hydrogenation reaction. As far as we know, this is the first work conducting the reaction using Co as the catalyst.
Au nanoparticles decorated mesoporous MnFe₂O₄ nanocrystal clusters (MnFe₂O₄/Au hybrid nanospheres) were used for the electrochemical sensing of As(III) by square wave anodic stripping voltammetry ...(SWASV). Modified on a cheap glass carbon electrode, these MnFe₂O₄/Au hybrid nanospheres show favorable sensitivity (0.315 μA/ppb) and limit of detection (LOD) (3.37 ppb) toward As(III) under the optimized conditions in 0.1 M NaAc-HAc (pH 5.0) by depositing for 150 s at the deposition potential of -0.9 V. No obvious interference from Cd(II) and Hg(II) was recognized during the detection of As(III). Additionally, the developed electrode displayed good reproducibility, stability, and repeatability, and offered potential practical applicability for electrochemical detection of As(III) in real water samples. The present work provides a potential method for the design of new and cheap sensors in the application of electrochemical determination toward trace As(III) and other toxic metal ions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Design and preparation of efficient and economical catalysts for direct hydroxylation of benzene to phenol is an important topic. In this work, a series of metal‐doped graphitic carbon nitride ...catalyst (Cu‐, Fe‐, V‐, Co‐, and Ni‐g‐C3N4) were successfully synthesized by using urea as the precursor through a facile and efficient method. The catalysts were characterized systematically using N2 adsorption–desorption, FTIR, thermogravimetric analysis, powder X‐ray diffraction, and X‐ray photoelectron spectroscopy techniques. It was found that the vanadium‐doped graphitic carbon nitride catalyst V‐g‐C3N4 was the most efficient catalyst for the direct synthesis of phenol from benzene with hydrogen peroxide as the oxidant and it could be recycled at least 4 times. The influence of reaction conditions such as the solvent, reaction temperature, reaction time, and the amounts of catalyst and hydrogen peroxide were investigated. Under optimized conditions, 18.2 % yield of phenol was obtained with the selectivity to phenol as high as 100 %.
Sharpen your pencils…︁ A vanadium‐doped graphitic carbon nitride catalyst (V‐g‐C3N4) was successfully synthesized by using urea as the precursor through a facile and efficient method. The catalyst showed high activity in the hydroxylation of benzene with a selectivity to phenol of 100 %. The system can be recycled at least 4 times without considerable decrease in the efficiency.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Superamphiphilic materials have great potential to enhance the mass transfer between phases in liquid–liquid catalysis due to their special affinities. Constructing superamphiphilic surfaces that ...possess superhydrophilic and superhydrophobic properties simultaneously has been a tough assignment. So, exploration of simple methods to prepare such materials using renewable and abundant feedstocks is highly desired. Here, we reported an effective strategy to construct superamphiphilic carbon directly from sodium lignosulfonate, which is a renewable resource from paper industry wastes. From the characterization of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) for superamphiphilic carbon, we found that element C was responsible for the hydrophobic nature and the existence of O and S endowed the carbon with hydrophilic characteristics. Further, micro/nanohierarchical pores were found beneficial for the superamphiphilicity of carbon. Meantime, in the selective hydrogenation of styrene, phenylacetylene, and cis-stilbene in liquid–liquid systems, conversion became double using superamphiphilic carbon compared with blank results, and the yields were three times more than those in blank experiments. The reasons were that superamphiphilic carbon induced the formation of Pickering emulsions and enriched the reactants around catalysts, as concluded by the characterization of confocal laser scanning microscopy and relating contrastive experiments. This work revealed a different route to obtain superamphiphilic carbon and provided a diverse perspective to promote Pickering emulsion catalysis by the superamphiphilicity of carbon.
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IJS, KILJ, NUK, PNG, UL, UM
Tuning the activity of supported metals by changing the properties of supports is a highly attractive strategy to realize some important reactions in biomass transformation. Herein, Ru nanoparticles ...supported on montmorillonite (MMT) and hydroxyapatite (HAP), denoted as Ru/MMT and Ru/HAP, were prepared. It was found that the activity of the Ru catalysts for different routes to convert biomass-derived 2,5-hexanedione (2,5-HD) could be controlled by the support materials. Ru/MMT was active for the synthesis of dimethyltetrahydrofuran from hydrogenation of 2,5-HD at 90 °C, while Ru/HAP showed excellent performance on the conversion of 2,5-HD into N-substituted tetrahydropyrroles at 30 °C via direct reductive amination. Systematic study revealed that the property of support materials influenced the activity of Ru/MMT and Ru/HAP for the different routes, affording different reaction pathways for conversion of 2,5-HD.
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IJS, KILJ, NUK, PNG, UL, UM
In this work, we found that inulin is soluble in ionic liquids (ILs) choline chloride (ChoCl)/oxalic acid and ChoCl/citric acid, which are prepared entirely from cheap and renewable materials. On the ...basis of this discovery, we conducted the one pot reaction for the conversion of inulin into 5-hydroxymethylfurfural (HMF), which is a potential substitute for petroleum-based building blocks, using the two ILs as catalysts and solvents. The effects of reaction time, temperature and water added on the reaction were studied. It is demonstrated that the ILs are very efficient for the reaction at relatively lower temperature and could be reused after simple separation.
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