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A modified solution combustion approach was applied in the synthesis of nanosize SrFeO3-δ (SFO) using single as well as mixture of citric acid, oxalic acid, and glycine as fuels with corresponding metal nitrates as precursors. The synthesized and calcined powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis and derivative thermogravimetric analysis (TG-DTG), scanning electron microscopy, transmission electron microscopy, N2 physisorption methods, and acidic strength by n-butyl amine titration methods. The FT-IR spectra show the lower-frequency band at 599 cm-1 corresponds to metal-oxygen bond (possible Fe-O stretching frequencies) vibrations for the perovskite-structure compound. TG-DTG confirms the formation temperature of SFO ranging between 850-900 °C. XRD results reveal that the use of mixture of fuels in the preparation has effect on the crystallite size of the resultant compound. The average particle size of the samples prepared from single fuels as determined from XRD was ~50-35 nm, whereas for samples obtained from mixture of fuels, particles with a size of 30-25 nm were obtained. Specifically, the combination of mixture of fuels for the synthesis of SFO catalysts prevents agglomeration of the particles, which in turn leads to decrease in crystallite size and increase in the surface area of the catalysts. It was also observed that the present approach also impacted the catalytic activity of the SFO in the catalytic reduction of nitrobenzene to azoxybenzene. [ABSTRACT FROM AUTHOR]

For the purpose of water purification,novel and low-cost adsorbentswhich are promising replacements for activated carbon are being activelypursued. However, a single-phase material that adsorbs both cationicand anionic species remains elusive. Hence, a low-cost, multiphaseadsorbent bed that purifies water containing both anionic and cationicpollutants is a desirable alternative. We choose anionic (Congo red,Orange G) and cationic (methylene blue, malachite green) dyes as modelpollutants. These dyes are chosen since they are widely found in effluentsfrom textile, leather, fishery, and pharmaceutical industries, andtheir carcinogenic, mutagenic, genotoxic, and cytotoxic impact onmammalian cells is well-established. We show that ZnO, (Zn0.24Cu0.76)O and cobalt ferrite based multiphase fixed adsorbentbed efficiently adsorbs model anionic (Congo red, Orange G) and cationic(methylene blue and malachite green) pollutants, and their complexmixtures. All adsorbent phases are synthesized using room-temperature,high-yield (∼96–100%), green chemical processes. Thenanoadsorbents are characterized by using X-ray powder diffraction(XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller(BET) surface area analysis, and ζ potential measurements. Theconstituent nanophases are deliberately chosen to be beyond 50 nm,in order to avoid the nanotoxic size regime of oxides. Adsorptioncharacteristics of each of the phases are examined. Isotherm basedanalysis shows that adsorption is both spontaneous and highly favorable.ζ potential measurements indicate that electrostatic interactionsare the primary driving force for the observed adsorption behavior.The isotherms obtained are best described using a composite Langmuir–Freundlichmodel. Pseudo-first-order, rapid kinetics is observed (with adsorptionrate constants as high as 0.1–0.2 min–1insome cases). Film diffusion is shown to be the primary mechanism ofadsorption. [ABSTRACT FROM AUTHOR]

A modified solution combustion approach was applied in the synthesis of nanosize SrFeO(3-δ) (SFO) using single as well as mixture of citric acid, oxalic acid, and glycine as fuels with corresponding metal nitrates as precursors. The synthesized and calcined powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis and derivative thermogravimetric analysis (TG-DTG), scanning electron microscopy, transmission electron microscopy, N2 physisorption methods, and acidic strength by n-butyl amine titration methods. The FT-IR spectra show the lower-frequency band at 599 cm(-1) corresponds to metal-oxygen bond (possible Fe-O stretching frequencies) vibrations for the perovskite-structure compound. TG-DTG confirms the formation temperature of SFO ranging between 850-900 °C. XRD results reveal that the use of mixture of fuels in the preparation has effect on the crystallite size of the resultant compound. The average particle size of the samples prepared from single fuels as determined from XRD was ∼50-35 nm, whereas for samples obtained from mixture of fuels, particles with a size of 30-25 nm were obtained. Specifically, the combination of mixture of fuels for the synthesis of SFO catalysts prevents agglomeration of the particles, which in turn leads to decrease in crystallite size and increase in the surface area of the catalysts. It was also observed that the present approach also impacted the catalytic activity of the SFO in the catalytic reduction of nitrobenzene to azoxybenzene.