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Water pollution have become contentious among researchers. By increasing industrialization, the availability of clean water has been reduced. Industrial dyestuffs contribute to the escalation of environmental pollution and are the largest group of organic compounds. The aim of the present work is the synthesis of nanostructures that accelerate the removal of organic dyes from water. To reach this aim, first, ZnMn2O4 nanostructures were synthesized by hydrothermal and co-precipitation methods using maleic acid and phenylalanine as a capping agent. Second, the nanostructures were characterized. XRD analysis revealed the formation of ZnMn2O4 with diameters about 32.3 nm. SEM analysis showed the formation of the agglomerated spherical ZnMn2O4 nanostructures with diameters lower than 50 nm. EDX analysis confirmed the purity of the prepared samples with the presence of Zn, Mn, and O. FT-IR analysis confirmed the bonding between Mn and O at about 620 cm-1. ZnMn2O4 nanostructures showed antiferromagnetic behaviors due to the super-exchange interactions between manganese ions. Finally, the photocatalytic behavior of the nanostructures was investigated for degradation of the anionic and cationic dyes. The results of the photocatalytic tests of two as-prepared samples via different methods were similar. The results exhibit a promising photocatalytic activity in the presence of 0.03 g photocatalyst for degradation of a dye solution with 10 ppm concentration. We introduced these conditions as optimum conditions and achieved maximum decolorization (92.43 %) in the 10 ppm of MV solution after 90 min. Also, we repeated six consecutive reaction cycles and observed a little activity loss after six reactions. We related this result to the high stability of the photocatalyst. We performed scavenging experiments to evaluate the active species involved in the photocatalytic process and plausible mechanisms. The photocatalytic degradation of MV decreased in the presence of TBA and BQ, respectively. This decrease indicated that OH° and O2°- radicals are important active species in the MV degradation process.
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The present work reports the sonochemical synthesis of DBNO NC (dysprosium nickelate nanocomposite) using metal nitrates and core almond as a capping agent. In addition, the effects of the power of ultrasound irradiation were investigated. The BaDy2NiO5/Dy2O3 and BaDy2NiO5/NiO nanocomposites were synthesized with sonication powers of 50 and 30 W, respectively. The agglomerated nanoparticles were obtained using different sonication powers, including 15, 30, and 50 W. The results showed that upon increasing the sonication power, the particle size decreased. After characterization, the optical, electrical, magnetic, and photocatalytic properties of the NC were studied. The nanocomposites showed an antiferromagnetic behavior. In this study, the photocatalytic degradations of two dyes, AR14 and AB92, were investigated in the presence of DBNO NC. Furthermore, the effects of the amount of photocatalyst, the concentration of the dye solution, the type of organic dye, and light irradiation on the photocatalytic activity of the nanocomposite were studied. The results showed that with an increasing amount of catalyst and decreasing concentration of dye, the photocatalytic activity of the nanocomposite was increased. This activity for the degradation of AR14 is higher than that of AB92. Both AR14 and AB92 dyes show higher photocatalytic degradation under UV irradiation than under Vis irradiation.
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This review investigates hydrothermal synthesis of metal selenides and diselenides. Briefly, structures, applications and formation mechanisms are studied. The strategies for developing metal selenides, including NiSe, NiSe2, Ni3Se2, CdSe, FeSe2, MnSe2, CoSe, CuSe, Cu1.8Se, CuSe2, Cu3Se2 and ZnSe are discussed. More of 50 hydrothermal methods used for the synthesis of metal selenides are discussed. As well as the investigation of the photocatalytic activities of these metal selenides are followed by different synthesis methods and strategies employed for the synthesis of them.
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CdFe12O19 nanostructures and nanocomposites were synthesized via sol-gel auto-combustion method. The CdFe12O19/CdTiO3 nanocomposites were prepared at 850 °C after 1 h calcination, when molar ratio of Cd:Ti is 1:1. Effects of the molar ratio of Cd:Ti, type of precursor and calcination temperature were investigated. Both nanostructures and nanocomposites were ferromagnetic at room temperature, with saturation magnetizations (Ms) 2.561 and 11.269 emu g-1, and coercivities (Hc) 696.517 and 969.068 Oe, respectively. SEM, TEM, FTIR, EDS and XRD showed morphology, composition and particle size of the products. VSM, UV-vis and CV were used to investigate the magnetic, optical and electrochemical properties. The band gap values of the nanocomposites were larger than that in the nanostructures. Also photocatalytic properties of the nanocomposites were investigated. This is the first attempt on the study of photocatalytic performance of the cadmium hexaferrite nanostructures and nanocomposites. The effects of various factors including composition and particle size of the nanocomposites, the Ti:Cd molar ratio and also kind of organic dye on the photocatalytic behavior of the products were evaluated. The photocatalytic activity achieved a maximum when ratio of Ti:Cd was 1:1. Methyl orange, methylene blue and methylene violet decompositions were about 71.35, 55.08 and 62.27% by nanocomposites, respectively.
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GCMO NSs were synthesized by the reaction of metal nitrate salts in the presence of stabilizing agent and PG, by a Pechini method. Citric acid, maleic acid, succinic acid and 1,3,5-benzenetricarboxylic acid were used as stabilizing agents. The structure, morphology, optical, magnetic and photocatalytic properties of the GCMO NSs were investigated using various characterization techniques. Effects of type of stabilizing agent, the molar ratio of stabilizing agent:PG and also calcination temperature on particle size and morphology of the products were investigated. Also the influence of kind of pollutant on photocatalytic behavior of GCMO NSs was evaluated.
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The sol-gel auto-combustion technique is an effective method for the synthesis of the composites. In this research for the first time, CoTiO3/CoFe2O4 nanocomposites are successfully synthesized via a new sol-gel auto-combustion technique. The glucose, maltose and starch are used as fuel, capping and reducing agents, also the optimal reducing agent is chosen. The effects of quantity of reducing agent, molar ratio of Ti:Co, calcination temperature and time on the morphology, particle size, magnetic property, purity and phase of the nanocomposites are investigated. XRD patterns show formation of CoTiO3/CoFe2O4 spherical nanoparticles with nearly evenly distribution, when the molar ratio of Co/Ti is 1:1. EDS analysis confirm results of XRD. The magnetic behavior of the nanocomposites is studied by VSM. The nanocomposites exhibit a high coercivity at room temperature.
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The design of nanostructures with favored shape, particle size and structure is one of the most important fields of nanoscience. To reach this target hydrothermal method is one of the most applicable methods which allow us to obtain favored structures by changing some parameters. This review focuses on synthesis of some transition metal sulfides by hydrothermal method because of technological importance of this group of material. The common sulfides of Mn, Co, Ni, Cu, Zn, Ag and Cd are introduced and a mechanism proposed for their synthesis. The effects of temperature and time reaction, surfactant, reactants concentration, metal and sulfur sources and etc. on the morphology, particle size and some properties of the products are investigated. SEM and TEM images show the morphology and size of the as-synthesized samples. Chemical composition of the samples is characterized by XRD, EDS and etc. The magnetic, optical and thermoelectric properties of the metal sulfides are investigated.
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Mercury selenide (HgSe) nanostructures were synthesized via a sonochemical method based on the reaction between HgCl(2), SeCl(4) and hydrazine hydrate (N(2)H(4)·H(2)O) in water, in presence of various capping agents. The effects of preparation parameters such as: the kind of capping agent and its amount, ultrasonic power, reaction time and temperature were investigated. It was found that morphology, particle size and phase of the products could be greatly affected by these parameters. HgSe nanostructures were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL) and X-ray energy dispersive spectroscopy (EDS).