Authors:Xie Hongqin, Wu Duilin, Jiao Zhe, Li Xiaowei, Zhang Shouwei, Lan Yan, and Cheng Cheng
A novel composite adsorbent, magnetite/hydroxyapatite (Fe3O4/HAP) composites, was prepared by biowaste chicken eggshell for the purpose of removing radiocobalt from aqueous solutions.
It highlighted that more than 92% Co(II) could be removed by using the developed composites under the experimental conditions.
The maximum sorption capacity of Co(II) on Fe3O4/HAP composites was 6.9 × 10−4 mol/g. The coexisted foreign ions, e.g., ClO4−, NO3−, Cl−, Na+ and K+, did not interfere the elimination of Co(II) from aqueous solutions, while Mg2+ did. The sorption process was found to be controlled well by pseudo-second-order and intra-particle diffusion models, and
the equilibrium data were simulated by Langmuir model very well with high correlation coefficients. The thermodynamic parameters
confirmed the spontaneity and endothermic nature of Co(II) sorption processes. After sorption, the Fe3O4/HAP composites could be effectively and fleetly separated from aqueous solutions by magnetic separation technique in large
scale. The Fe3O4/HAP composites are suitable materials in the preconcentration of Co(II) from large volumes of aqueous solutions.
Authors:S. Hosseini, A. Mohamad, A. Kadhum, and W. Wan Daud
A study concerned to thermogravimetric analysis is performed in cesium dihydrogen phosphate (CsH2PO4) that was synthesized, using cetyltrimethylammonium-bromide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and mixture of
(F-68:CTAB) with two mole ratio 0.06 and 0.12 as surfactant. The dehydration behavior of particles was studied using thermal
gravimetric analysis and differential scanning calorimetric. Subsequently, the experimental results indicated that the first
dehydration temperature in the range of 237–239 °C upon heating, the second peaks occur at temperature range 290–295 °C and
overlapping in the thermogravimetric events is observed. The mass loss values are obtained in the range of 6.62–6.97 wt% that
is less than reported theoretical value 7.8 wt%. These values show well compatibility of reaction CsH2PO4 to Cs2H2P2O7 with 3.92 wt% whereas mass loss value of CsH2PO4 to CsPO3 is less than theoretical value 7.8 wt%. The activation energy of two steps dehydration are calculated using Kissinger equation
for the samples synthesized via CTAB and (F-68) with minimum value mass loss 6.62% and maximum value mass loss 6.97%, respectively.
The calculation results reveal that the reaction rate in the first step (CsH2PO4 → Cs2H2P2O7) is faster than the second step (CsH2PO4 → CsPO3). The weight loss values of the samples demonstrate that existence of CTAB can be considered as effective factor which prevents
more weight loss during the dehydration process.
Authors:P. Pulišová, J. Boháček, J. Šubrt, L. Szatmáry, P. Bezdička, E. Večerníková, and V. Balek
Thermogravimetry-differential thermal analysis, emanation thermal analysis, mass spectrometry detection, Fourier transform
infrared and XRD were used to characterize thermal behaviour of titanium dioxide photocatalyst precursors prepared by precipitation
at various conditions from peroxotitanic acid sols. The transmission electron microscopy HRTEM technique was used to characterize
the surface microstructure. The sols contained TiO2 anatase particles of approximately 10 nm in diameter. During heating of the air dried samples, their chemical degradation
took place giving rise to anatase. On further heating, the crystallization of anatase and formation of rutile phase was observed.
To test the photocatalytic activity of the samples, the decomposition of 4-chlorophenol (4-CP) under ultraviolet and visible
irradiation was monitored. It was shown that photocatalytic activities of the samples are comparable to the Degussa P25 photocatalyst
Authors:José Delben, Odair Pimentel, Marlene Coelho, Pollyanna Candelorio, Leonardo Furini, Fábio Alencar dos Santos, Fábio de Vicente, and Angela Delben
Calcium phosphate bioactive glasses (BG) and some ceramics are candidates for implantation due to their excellent bonding
to bone. Silver is a bactericidal element and can be easily introduced in glasses and ceramics. In this work, nanometer-sized
bioactive glass particles doped with silver were produced and characterized by Thermal Gravimetric analysis (TG), Fourier
Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD). Water hygroscopy
was reduced with increasing silver content. The increase in the amount of silver caused an increase in quartz and metallic
silver crystallization while reducing the BG transformation into hydroxyapatite. It was observed the silver reduction leading
to metallic silver formation for bioactive glasses containing high amount of silver.
Al2CoO4–PbCrO4 and Al2CoO4–Pb2CrO5 crystalline powders in different proportions were obtained by the polymeric precursor method. Differential scanning calorimetry
(DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during
synthesis. The TG and DSC results revealed a series of overlapping decomposition reactions due to different exothermal events,
which were identified as H2O and NOx elimination and polymer pyrolysis. The X-ray diffraction patterns of the xAl2CoO4–(1 − x)PbCrO4 and xAl2CoO4–(1 − x)Pb2CrO5 mixed compounds, with x = 1, 0.75, 0.5, 0.25 and 0, were obtained in the crystalline form with their respective phases, and proved consistent with
the nominal compositions. The synthesis of these two systems yielded nine different colors and shades.
Authors:Lidija Ćurković, Davor Ljubas, and Hrvoje Juretić
The efficiency of color removal from aqueous Congo Red dye (CR) solution has been investigated in TiO2 suspensions irradiated with artificial UV light. Batch photocatalytic tests were carried out by varying the amount of TiO2 and the irradiation time using the same initial CR concentration. The experimental results indicated that the decolorization
rate follows pseudo first-order kinetics with respect to CR concentration. The doses of TiO2 were 0.25, 0.5 and 1.0 g L−1 and the wavelength of incident ultraviolet light was predominantly 254 nm. CR adsorption on the surface of TiO2 is also investigated and described.
Authors:P. Thomas, K. Dwarakanath, K. Varma, and T. Kutty
A complex oxalate precursor, CaCu3(TiO)4(C2O4)8·9H2O, (CCT-OX), was synthesized and the precipitate that obtained was confirmed to be monophasic by the wet chemical analyses,
X-ray diffraction, FTIR absorption and TG/DTA analyses. The thermal decomposition of this oxalate precursor led to the formation
of phase-pure calcium copper titanate, CaCu3Ti4O12, (CCTO) at ≥680°C. The bright-field TEM micrographs revealed that the size of the as synthesized crystallites to be in the
30–80 nm range. The powders so obtained had excellent sinterability resulting in high density ceramics which exhibited giant
dielectric constants upto 40000 (1 kHz) at 25°C, accompanied by low dielectric losses, <0.07.
Metal carboxylato-hydrazinates are very good precursors for the synthesis of metal as well as mixed metal oxides as these
decompose to nanosized oxides with high surface area most of the times at comparatively lower temperatures. In the present
study one such novel precursor nickel manganese fumarato-hydrazinate (NiMn2(C4H2O4)3·6N2H4) has been prepared and characterized by XRD, FTIR and chemical analysis. The thermal decomposition of the precursor has also
been studied by isothermal, differential thermal and thermogravimetric analysis. The precursor shows two-step dehydrazination
followed by decarboxylation to form NiMn2O4. The infrared spectra show N-N stretching frequency at 965 cm−1, which confirm the bidentate bridging hydrazine. XRD confirms the formation of single phase NiMn2O4.