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RISS 인기검색어
- 검색키워드
- 저자 : Nemat Tahmasebi (검색결과 5 건)
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Nemat Tahmasebi,Marzieh Khalildashti 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3
MoO3 and reduced molybdenum oxides (MoOx, x=2.87 and 2) were successfully synthesized through a onepot hydrothermal method without and with adding polymeric surfactants (PVP or PVA) as capping and reducing agents into the reaction solution. The synthesized nanostructures were characterized by different techniques. Adding polymeric surfactants into hydrothermal reaction solution had significant effect on the structural, optical and morphological properties of products. Orthorhombic phase of MoO3 nanorods, monoclinic phase of MoO2.87 nanoparticles and monoclinic phase of MoO2 nanoparticles were obtained in the absence and in the presence of PVP and PVA, respectively. The specific surface area of MoO3, MoO2.87 and MoO2 samples calculated by the BET method was found to be 15.64, 5.94 and 87.62m2g1, respectively. The dye adsorption capability of products was investigated for removal of RhB molecules from water. The experimental results indicated that the RhB adsorption on MoO2 is much faster and higher than that of MoO3 and MoO2.87, which can be attributed to the larger specific surface area. Furthermore, the kinetic models and isotherm models were studied to determine the adsorption rate and mechanism of RhB adsorption onto the products.
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Leila Derikvand,Nemat Tahmasebi 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1
The present study examined the effects of adding bismuth oxyhalides, BiOCl, BiOBr and BiOI, on the photocatalytic properties of Bi2WO6. The samples were synthesized using a simple one-stage hydrothermal method. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance spectroscopy (DRS) and the nitrogen absorption/desorption technique. The activity of the products on the photocatalytic degradation of an aqueous Rhodamine B (RhB) solution was then investigated under visible light irradiation. The results showed the higher photocatalytic efficiency of the hybrid Bi2WO6/BiOBr sample compared to that of other compounds, as approximately 97% of RhB molecules were degraded after 80minutes of irradiation in the presence of this sample. Under the same conditions, pure Bi2WO6 and hybrid samples of Bi2WO6/BiOCl and Bi2WO6/BiOI, respectively, degraded 40%, 60% and 20% of dye molecules in the solution. The better performance of this sample compared to that of the others can be explained by its larger effective surface area and the strong interaction between Bi2WO6 and BiOBr. Furthermore, a test conducted to determine active species in photocatalytic reactions showed that superoxide radicals played the main role in the degradation of RhB molecules by hybrid Bi2WO6/BiOBr photocatalyst.
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Azadeh Khane,Nemat Tahmasebi,Hesam Seyed Kaboli 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.5
This study pioneered the synthesis of BiOCl/Bi2Mo3O12 as a composite photocatalyst using a simple onestephydrothermal method with polyvinylpyrrolidone (PVP) as a structure-directing agent. Characterizing the synthesizedsamples using different physical and chemical techniques indicated the presence of PVP in reaction solution isbeneficial to growth Bi2Mo3O12 phase. In addition, the synthesized samples in the presence of PVP display a red-shift inthe bandgap, which improves light absorption in the visible region. The photocatalytic performance of the samples wasinvestigated in terms of the decolorization of rhodamine B (RhB) under visible light irradiation. Comparing the photocatalyticperformance of synthesized samples using different PVP amounts (0-0.5 g) showed their optimal performancein the presence of 0.1 g of PVP. Results indicated that nearly 98% of RhB was degraded within 60min undervisible light irradiation. The pH effect of the RhB solution and catalyst amount on photocatalytic performance werealso investigated, and active species trapping determined the main species participating in photocatalytic reactions.
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Shafaati Saideh,Hakimyfard Alireza,Tahmasebi Nemat,Kafi-Ahmadi Leila,Khademinia Shahin 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
Solid state synthesis of some new Mx-CuSb2O6-CuSb2O4 (Mx=None, Fe, Ni, Ce and Yb) nanocomposites was introduced in the present research study. The physicoelectrochemical properties of synthesized nanocomposites were investigated by different techniques, such as XRPDT, Rietveld, FTIR, FESEM, UV-Vis, VSM, CV and EIS. Rietveld analysis data revealed that all of the synthesized samples display the monoclinic crystal phase with the space group of P21/n. The estimated direct band gap energy of the obtained nanocomposites was in the range of 2.0 to 2.7 eV, which confirms that are active in ultraviolet-visible region. The VSM data indicated that the maximum magnetic behavior was found for Ni doped — Cu−Sb−O nanocomposite. Also, the catalytic performance of nanocomposites to synthesis 2-amino-4H-benzochromenes under ultrasonic and microwave was investigated. The considered parameters, such as solvent type, catalyst amount and reaction time, influencing the yield of the 4H-benzochromene reaction were studied. The maximum yield for the synthesizing of the 4H-benzochromene compounds was obtained when EtOH was used as the reaction solvent. The catalyst amount and reaction time were 15 mol% and 8 min, respectively, under ultrasonic conditions, while benzaldehyde was used as an aldehyde derivative.
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Mirzazadeh Amene,Hakimyfard Alireza,Tahmasebi Nemat,Kafi-Ahmadi Leila,Khademinia Shahin 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5
This paper presented the synthesis of Mx-ZnBi2O4–Bi2O3 (Mx = Fe, Co, Ni, Eu, and Ho) nanomaterials by a one-pot facile solid-state method at 650 ˚C for 10 h. Rietveld analysis data displayed the formation of ZnBi2O4–Bi2O3 composite in which ZnBi2O4 was crystallized as a main phase in orthorhombic crystal system with Pmmm space group. The investigation of optical properties indicated that doping the metal ions into the ZnBi2O4–Bi2O3 nanocomposite decreased the band-gap energy amount. Results indicated that the synthesized samples displayed paramagnetic behavior without any preferred magnetization direction. However, the data indicated that Co3+-doped ZnBi2O4 showed highest magnetization value. In addition, cyclic voltammetry (CV) data and low EIS values revealed a pseudocapacitor behavior of the synthesized samples. Biginelli reaction to synthesize heterocyclic DHPMs compounds was applied to evaluate the catalytic performance of the samples. Results indicated that the synthesis yields of DHPMs at optimum condition were 92% and 96% for undoped and Eu-doped ZnBi2O4–Bi2O3, respectively.
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