Xubiao Luo,Fang Deng,Lujuan Min,Shenglian Luo,Bin Guo,Guisheng Zeng,Chaktong Au
Inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time- as well as solvent-consuming. Compared to nonimprinted TiO2/WO3, the molecularly imprinted TiO2/WO3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO2/WO3 toward the target molecules is more than two times that of non-imprinted TiO2/WO3, a result of selective adsorption of target molecules on molecularly imprinted TiO2/WO3. The formation pathway of intermediate products in 2-nitrophenol and 4-nitrophenol degradation process was provided. Moreover, molecularly imprinted TiO2/WO3 exhibits high stability. The results indicate that inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites have a promising prospect in the treatment of wastewater for irrigation.
In this work, three kinds of bimetallic Prussian blue analogues (PBAs), i.e. K x Ni [Fe(CN) 6 ]·nH 2 O (NiFe-PBA), K x Co [Fe(CN) 6 ]·nH 2 O (CoFe-PBA), and K x Mn [Fe(CN) 6 ]·nH 2 O (MnFe-PBA), were synthesized by a simple precipitation method under identical conditions. Their chemical compositions , structures, morphologies, valences of transition metals, and electrochemical sensing performances for 2-nitrophenol (2-NP) are examined in details. It is found that all the prepared PBAs hold face-centered-cubic structures with near perfect cube morphologies for NiFe-PBA and CoFe-PBA and truncated cube morphology for MnFe-PBA. For the electrochemical detection of 2-NP, a wide detection range of 1.0–700.0 μM was obtained at all PBAs modified electrodes together with the sensitivities of 443.3, 368.0, and 339.0 μA cm −2 mM −1 and detection limits of 0.28, 0.46, and 0.59 μM achieved at NiFe-PBA, CoFe-PBA, and MnFe-PBA modified electrodes, respectively. The superiority in electrochemical sensing performance of NiFe-PBA to CoFe-PBA and MnFe-PBA may stem from its higher conductivity, lager electroactive surface area, and better intrinsic catalytic property of the transition metal in its framework. Furthermore, the constructed NiFe-PBA-based sensor displays good repeatability, long-term stability, and high selectivity together with desirable recoveries (97.8–103.9%) for the assay of 2-NP in water samples. The present work is the first report on the PBAs-based electrochemical sensors for 2-NP detection, which may promise a future of PBAs or PBAs-based materials for sensing applications.
Tahseen Kamal,Ikram Ahmad,Sher Bahadar Khan,Abdullah M. Asiri
This article presents the preparation and catalytic performance of carboxymethyl cellulose stabilized nickel nanoparticles (CMC-Ni) and bacterial cellulose coated with it (CMC-Ni-BC) in the colloidal form and dip-catalyst, respectively. Ni nanoparticles were prepared by mixing nickel chloride and CMC aqueous solutions with reductant followed by quick microwave heating treatment. In a separate experiment, BC was synthesized by Gluconacetobacter xylinum . After purification, the synthesized BC was coated with the prepared CMC-Ni. The CMC-Ni-BC catalytic efficiency was evaluated in anionic 2-nitrophenol (2-NP) and cationic methylene blue (MB) dye reduction reactions by sodium borohydride. While using the similar reaction conditions for the 2-NP reduction, the suspension form of CMC-Ni catalyst showed higher reduction reaction rate constant as compared to the dip-catalyst of CMC-Ni-BC. Similarly, high reaction rate constant was observed for the CMC-Ni in comparison with the CMC-Ni-BC while performing the MB reduction reaction. However, supported type Ni catalyst was easily applied in further reactions without the need of further processing which is needed in the case of colloidal form of the catalyst. Moreover, the CMC-Ni-BC catalyst was also tested in the complex situation using the binary solution of 2-NP and MB for their simultaneous reductions. As high as 7.89 min −1 of reaction rate constant was calculated for the reduction of cationic MB by anionic polysaccharide stabilized Ni nanoparticles-coated BC.
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