Papers by Keyword: Coprecipitation Method

Abstract: An experimental study to determine the effect of Cu doping on structural properties of ZnO nanoparticle has been conducted. Zn_1-xCu_xO (CZO) were prepared by co-precipitation method by varying Cu concentration with x = 0.00, 0.10, 0.11 and 0.12. The structural properties of the CZO sample were characterized by X-Ray diffraction (XRD) and X-ray Absorption Spectroscopy (XAS), which consist of XANES (X-ray Absorption Near-Edge Spectroscopy) and EXAFS (Extended X-ray Absorption Fine Structure). XAS measurements were performed in the energy of Cu K-edge and Zn K-edge using synchrotron radiation at SLRI (Synchrotron Light Research Institute) in Thailand. Both Cu K-edge and Zn K-edge XANES spectra indicate that the oxidation states of Cu and Zn ions are 2+. Analysis of XRD data with refinement method using Rietica software confirms the presence of Cu as doping in ZnO host lattice with the crystallite size ranging between 26 and 44 nm. Moreover, it shows that the obtained CZO samples are polycrystalline with (002) predominant reflection and exhibit a hexagonal wurtzite structure.

Abstract: In this work, the synthesis of magnetite/PEG nanoparticles combined with curcumin was conducted by using a simple coprecipitation method. The samples obtained were characterized using XRD, FTIR, and VSM for their structural and magnetic properties. Meanwhile, investigation of the potential as drug delivery agents was done through the drug release test using doxorubicin. The diffraction data analysis presented the addition of curcumin slightly decreased the diffraction peak of magnetite compared to without curcumin. The crystallite sizes of the magnetite/PEG and magnetite/PEG/curcumin were 13.9 nm and 13.7 nm, respectively. The functional group of the magnetite/PEG showed the presence of Fe-O bonds at a wavenumber of 587 cm^-1 and 421 cm^-1 originating from magnetite. Meanwhile, C-O-C and C-H bonds were observed at wavenumbers of 1108 cm^-1 and 2883 cm^-1 arising from PEG. Despite Fe-O, C-O-C, and C-H bonds, in magnetite/PEG/curcumin, it was also detected C=O bond at a wavenumber of 1621 cm^-1, indicating the presence of the curcumin. Regarding the magnetic properties, the saturation magnetization value of the magnetite/PEG nanoparticles decreased after adding curcumin. Interestingly, the results of the doxorubicin drug release of the magnetite/PEG and magnetite/PEG/curcumin nanoparticles showed excellent performance as drug delivery agents.

Abstract: Low thermal expansion ceramics have been widely applied in multiple fields. In this paper, a series of low thermal expansion ceramics SrZr_4-xTi_x(PO₄)₆ was prepared and characterized. The SrZr_4-xTi_x(PO₄)₆ ceramics could be well sintered in the temperature range of 1400~1500 °C. The effect of the addition of Ti substituting Zr and the sintering temperature was studied. The Ceramic with x =0.1 sintered at 1450 °C, the SrZr_4-xTi_x(PO₄)₆ had a high relative density. The thermal expansion coefficients were about 3.301×10^-6 °C^-1. It was demonstrated that the microstructure of the SrZr_4-xTi_x(PO₄)₆ could be altered by adding varying amount of Ti to tailor the thermophysical properties of the material.

Abstract: Ceramics with the formula Ca_1-xSr_xZr₄(PO₄)₆ (x=0.4, 0.45, 0.5, 0.55) have been synthesized by coprecipitation method, an. their structures, phase transitions, thermal expansion properties have been studied by differential sanning calorimetry, scanning electron microscope, X-ray diffraction and dilatometer. The results show that Ca_1-xSr_xZr₄(PO₄)₆ ceramics sintered at 1400°C had good sintering condition. Unit cell volume basically had no change with substitution of Ca by Sr. The coprecipitation method saved energy and time. It was introduced to increase the relative density of Ca_0.5Sr_0.5Zr₄(PO₄)₆ ceramic. The coefficient of thermal expansion was about 1.447×10^-6/°C.

Abstract: Metal oxide nanocomposite (ZnO-CuO) was successfully synthesized by one step homogeneous coprecipitation method and further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), X-ray diffraction analysis (XRD) and UV-visible diffuse reflectance spectra. XRD analysis exhibited presence of pure copper oxide and zinc oxide within the nanocomposite. SEM analysis indicated that the ZnO-CuO nanocomposite was consisted of flower shaped ZnO along with leaf shaped CuO. Photocatalytic activity of nanocomposite was evaluated in terms of degradation of methylene blue (MB) dye solution under ultra-violet radiation. Results showed that the photocatalytic efficiency of ZnO-CuO nanocomposite was higher than its individual pure oxides (ZnO or CuO).

Abstract: Y-Mg-Al-LDO is successfully prepared by coprecipitation method and heat treatment. The catalytic performance of Y-Mg-Al-LDO is evaluated in the preparation of isophorone by condensation of acetone. The results shows that the Y-Mg-Al-LDO catalyst has higher activity under the reactive conditions of 300 °C and 6 mL·h^-1 charging air speed so as to the conversion of acetone improved 17.8 % and the selectivity of isophorone increased 11.0 %. The products were characterized by XRD, FT-IR, CO₂-TPD and BET. The results indicated that the basicity, the number of strong base center and pore volume and pore size of Y-Mg-Al-LDO were increased. Large ion Y³⁺ softened hydrotalcite porous structure, but did not change its layered crystal structure. The crystallinity of hydrotalcite was affected due to the amount of doped Y³⁺. Y₂O₃ was highly dispersed when small amount of Y³⁺ was doped, and laminates were distorted because of some of Y³⁺ was risen out of the scope of Mg²⁺ in the lattice when a large amount of Y³⁺ was doped.

Abstract: A series of CeO₂-SiO₂ composite nanoparticles with different cerium and silica (Ce/Si) mole ratios were synthesized via a coprecipitation method using cerium nitrate, tetraethylorthosilicate and ammonia as raw materials. X-ray diffraction (XRD), fourier transform infrared spectrology (FT-IR), thermogravimetry-differential scanning calorimetry (TG/DSC), transmission electron microscopy (TEM) and energy dispersive analysis of X-ray (EDAX) were used to characterize the CeO₂-SiO₂ nanoparticles. With the increase of CeO₂ content, the crystal of CeO₂ grew up gradually and the average crystallite size of the CeO₂ decreased. There are Ce-O-Si bonds in the CeO₂-SiO₂ composite nanoparticles. The particle size of the CeO₂-SiO₂ composite nanoparticles with a Ce/Si mole ratio of 1 is about 20–30 nm. The dispersion stability of the CeO₂-SiO₂ composite nanoparticles with a Ce/Si mole ratio of 1 was studied. It was found that cationic and nonionic surfactant could obviously affect the dispersion stability of suspension, but not the anion surfactant. A suspension with CeO₂-SiO₂ composite nanoparticles at 0.1 wt% was added in 0.1 g/L cationic surfactant CTAB, and its pH value was adjusted within the range of 10-10.5. In this condition, the stable suspension without sedimentation time was successfully obtained.

Abstract: Synthesis of Zn doped Barium M-Hexaferrite (BaFe_12-xZn_xO₁₉) has been performed by co-precipitation method. The purified iron sand from Tulungagung is used as a precursor of Fe₃O₄. Synthesis of Zn doped Barium M-Hexaferrite (BaFe_12-xZn_xO₁₉) with variations of x = 0.3, 0.5, and 0.7 wt % has been calcined at temperatures of 1000°C for 5 hours. Ion Zn²⁺ (with 0 ≤ x ≤ 0.7 wt %) does not change the crystal structure of Barium M-Hexaferrite (BaM), but give a slight displacement of the peak position of the diffraction pattern. SEM figures showed that Zn doped Barium M-Hexaferrite (BaFe_12-xZn_xO₁₉) have a hexagonal structure, similar to BaM structure. Doping of Zn has changed the magnetic properties of Barium M-Hexaferrit (BaM), from hard magnetic become soft magnetic. Barium M-Hexaferrit (BaM) has a value of Coercivity Field (H_c) and Remanence Magnetization (M_r) is 0.03734 T and 8.334 emu/g. At variation x = 0.3, the Remanence Magnetization (M_r) reaches the highest value. At this point, a value of Coercivity Field (H_c) and Remanence Magnetization (M_r) is 0.0506 T and 14.782 emu/gram respectively.

Abstract: Bauxite waste sludge as a raw material, the use of reverse chemical coprecipitation synthesize Fe₃O₄. Researching temperature, precipitation concentration, aging time and Fe²⁺/Fe³⁺ molar ratio effect on the particle size, morphology. Optimal experimental conditions: temperature 70 °C, the precipitant NaOH mass ratio of 10%, aging time 3h, Fe²⁺/Fe³⁺ molar ratio of 2:3. Test methods using a laser particle size analyzer, XRD analysis of the products were characterized, the product is Fe₃O₄, the average particle size of 0.11mm.

Abstract: CeO₂-Fe₃O₄/TiO₂ and CeO₂/TiO₂ catalysts were prepared by coprecipitation method, and their activities for selective catalytic reduction of NO with NH₃ were investigated. As can be seen from the experimental results, the CeO₂-Fe₃O₄/TiO₂ catalyst prepared showed the best SCR activity and SO₂ resistance. Based on the characterization results of BET, XRD, NH₃-TPD and XPS the excellent performance of CeO₂-Fe₃O₄/TiO₂ catalyst should be resulted from its large surface area, high NH₃ adsorption capacity and high concentration of surface chemisorbed oxygen.