ABSTRACT
Aniline is an organic pollutant with carcinogenicity and teratogenicity, while F- and Hg2+ are toxic ions that are easily soluble in water. When they are released to the environment, they will pose a threat to human health. Designing a material that can simultaneously detect three types of pollutants is of great significance. In this paper, a novel rare earth metal organic framework material (Eu-MOF) with three-dimensional structure based on 1-methylimidazole-4,5-dicarboxylic acid was synthesized for the first time through solvent thermal method. It has excellent luminescent performance and can be used as a multifunctional fluorescent probe to detect aniline, F-, and Hg2+ based on photoinduced electron transfer, energy competitive absorption, and ion exchange mechanisms, with detection limits of 1.79 × 10-8, 8.13 × 10-8, and 8.83 × 10-7 M, respectively. It is worth noting that Eu-MOF can detect F- and Hg2+ in real water samples, such as lake water and green tea water, with favorable recovery rates.
ABSTRACT
Embedding both boron and nitrogen into the backbone of acenes to generate their isoelectronic structures has significantly enriched the acene chemistry to offer appealing properties. However, only small BN-heteroacenes have been extensively investigated, with BN-heptacenes as the hitherto longest homologue. Herein, we report the synthesis of three new nonacene BN-isosteres via incorporating a pair of antiaromatic B2 C4 and N2 C4 heterocycles, representing a new length record for BN-heteroacenes. The distance between the B2 C4 and N2 C4 rings affects the contribution of the charge-separated resonance forms, leading to tunable antiaromaticity of the two heterocycles. The adjusted local antiaromaticity manifests substantial influence on the molecular orbital arrangement, and consequently, the radiative transition rate of BN-3 is greatly enhanced compared with BN-1 and BN-2, realizing a high fluorescence quantum yield of 92 %. This work provides a novel design concept of large acene BN-isosteres and reveals the importance of BN/CC isosterism on their luminescent properties.
ABSTRACT
Currently, designing novel noble-metal-free photocatalysts with efficient carriers migration and catalytically active sites have been a researching hotspot in photocatalytic hydrogen evolution. In this paper, a novel noble-metal-free Mo2C-In2S3 heterojunction was synthesized by a simple hydrothermal method. Morphology characterization revealed In2S3 was attached to Mo2C. Electrochemical results showed Mo2C improved the interface conductivity, and promoted the transportation of photogenerated carriers. Under visible light, the optimal Mo2C-In2S3 composite achieved a H2 generation rate of 535.58 µmol h-1 g-1, which was 175.6 and 25.8 times higher than pristine In2S3 (3.05 µmol h-1 g-1) and In2S3-1% Pt (20.73 µmol h-1 g-1). In addition, a reasonable mechanism of the elevated photocatalytic activity was also discussed. This study demonstrates commercial Mo2C has an important effect of separating carriers and replacing Pt as co-catalyst in heterojunctions. This research also provides a method to design and synthesize new noble-metal-free photocatalysts for excellent hydrogen production activity.
ABSTRACT
A new Schiff base derivative fluorescence-colorimetric chemosensor 2-hydroxy-5-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H3L), has been designed and synthesized. H3L displayed high selectivity and sensitivity for detecting Cr3+, Cu2+, Fe3+ and Al3+ ions in DMF/H2O (v/vâ¯=â¯1/1) solution. When Cr3+, Cu2+ or Fe3+ ions were added, the solution of H3L in DMF/H2O exhibited different color changes. While with the addition of Fe3+ or Al3+ ions, the solution of H3L in DMF/H2O displayed different fluorescence responses. The bonding modes and bonding ratios of H3L and metal ions were explored by the Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The detection limits of H3L with Cr3+, Cu2+, Fe3+and Al3+ ions were 3.37â¯×â¯10-7â¯M, 4.65â¯×â¯10-7â¯M, 3.58â¯×â¯10-7â¯M and 4.89â¯×â¯10-7â¯M, respectively.
ABSTRACT
In the pyrometallurgical treatment for spent lithium-ion batteries (LIBs), lithium is generally present in slag with Al, Ca and Si and is hard to be further treated. In this study, lithium was recovered from a simulated pyrometallurgical slag (pyro-slag) via sodium roasting and water leaching. The thermodynamic process for the reactions between slag and additives such as NaCl, NaNO3 and Na2SO4 were simulated during roasting by the HSC software, where Na2SO4 possessed stronger chemical reactivity. The optimal conditions for roasting were experimentally determined to be 800 °C for 60 min and an Na2SO4/Li molar ratio of 3 : 1, followed by water leaching at 70 °C for 80 min using a liquid-to-solid (L/S) mass ratio of 30 : 1. This yielded a maximum of 93.62% lithium recovery. The mechanism by which insoluble lithium in slag was transformed into soluble lithium by salt roasting was proposed using the analysis of XRD and EDS spectra, in which ion exchange occurred between Na+ and Li+ at a certain temperature.
ABSTRACT
This manuscript studies the fluorescent property of 3-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H2L). Fluorescent spectra show that in different solvents, H2L displays different fluorescent properties, which can be attributed to the interaction between the solvents and H2L. Further study indicates that H2L exhibits a highly selective and sensitive recognition for Hg2+ ions in dimethylsulfoxide (DMSO), Al3+ ions in methanol and N,N'-dimethylformamide/water (DMF/H2O, 1/1, v/v). The bonding modes and bonding ratio of H2L and metal ions in different solvents are explored by Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The probable mechanisms were discussed.
ABSTRACT
In the title mol-ecule, C(28)H(18)O(10), the two central benzene rings form a dihedral angle of 31.0â (1)°. In the phthalic acid fragments, the carb-oxy groups in the meta positions are approximately coplanar with the attached benzene rings, being inclined to their planes at 2.7â (1) and 10.3â (1)°, while the carb-oxy groups in the ortho positions are twisted from the benzene ring planes by 83.5â (1) and 75.4â (1)°. In the crystal, O-Hâ¯O hydrogen bonds link the mol-ecules into layers parallel to the bc plane. Weak C-Hâ¯O hydrogen bonds and π-π inter-actions between the aromatic rings [centroid-centroid distance = 3.7674â (3)â Å] further consolidate the crystal packing.
ABSTRACT
A novel kind of carbon nanotubes/titanium dioxide (CNTs/TiO2) composite photocatalyst was prepared by a modified sol-gel method in which the nanoscaled TiO2 particles were uniformly deposited on the CNTs modified with poly(vinyl pyrrolidone) (PVP). The composites were characterized by a range of analytical techniques including high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show the successful covering of the CNTs with PVP, forming core-shell structure. The nanoscaled TiO2 particles were uniformly deposited on the surface of CNTs reducing the bare CNTs which avoid losing the absorption and scattering of photons. The combination of CNTs and TiO2 particles imply the enhanced interactions between the CNTs and TiO2 interface which possibly becomes heterojunction. The composites become mesoporous crystalline TiO2 (anatase) clusters after annealing at 500 degrees C, and the surface area increases obviously. The photocatalytic activities of surface modification CNTs/TiO2 (smCNTs/TiO2) composites are extremely enhanced from the results of the photodegradation of methylene blue (MB).
ABSTRACT
Hydrous oxides of cerium, aluminum, nickel and copper were prepared by alkaline precipitation method. Langmuir adsorption isotherm was studied and specific surface area was measured by BET method through N2 adsorption-desorption process. IR characterization of hydrous metal oxides before and after fluoride adsorption was also studied. Results show that different hydrous metal oxides have different specific surface areas and their pore size distributions also are not all the same. Adsorption capacity is not directly dependent on the specific surface area. Isotherm study indicates that the adsorption follows Langmuir model and shows the feature of monolayer adsorption. IR study before and after fluoride adsorption shows that different hydrous metal oxides have similar adsorption sites in the same IR region as well as adsorption sites in the different IR region. The comprehensive interaction of these adsorption sites with fluoride ions results in the different adsorption capacity of different hydrous metal oxides.
ABSTRACT
Ferrocene was used as a catalyst, and xylene as carbon source. Chemical vapor deposition method was used to synthesize carbon nanotubes (CNTs). The CNTs were treated by oxidation method with concentrated nitric acid. Magnetic carbon nanotubes were prepared by using chemical co-precipitation. The products were characterized by field emission scanning electron microscope. This paper is concerned with the adsorption of methyl orange by magnetic carbon nanotubes. The best experimental conditions were found. Adsorbent solution was analyzed by UV-Vis adsorption spectra. At the same time, desorption and re-adsorption of methyl orange from magnetic CNTs were studied.
ABSTRACT
The potential of recovering propionic acid from discharged water in vitamin B(12) production by anaerobic fermentation was investigated in this paper. A primary amine, N(1923), was used as the extractant, kerosene as diluter and n-octanol as modifier. The influences of the content of N(1923) in the organic phase, the phase ratio and the pH of aqueous phase on the extraction yield of propionic acid were studied. The organic phase composition with the volume ratio was proposed of N(1923):kerosene:n-octanol as 45:35:20. Under conditions of the phase ratio (o/w) as 1:4, the pH of aqueous phase of 3.0 and after 5 min extraction, the extraction yield of propionic acid can be over 97%.
