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•The highest total VFAs concentration at RT=5days was achieved at acidic environment.•Alkaline environment was favorable at long RT due to WAS disintegration.•Acetate dominated all of ...the VFAs most likely due to WAS disintegration.•Caproate concentration doubled with prolonging RT from 5 to 15days.
Mixed culture fermentation consists of stable microbial population hence waste could be potentially used as a substrates. The aim of the work was to investigate the impact of pH and retention time on the anaerobic mixed culture fermentation. Trials at different pH (4–12) in unbuffered systems were conducted for 5, 10 and 15days. The highest VFAs concentration was achieved after 15days at pH 10 (0.62g/gVSadded), promising results were also achieved for pH 11 (0.54g/gVSadded). For pH 4 and short retention time propionic acid was the major product instead of acetic acid. For batches run at 15days (besides pH 6) caproic acid presence was noticed whereas at pH 11 occurrence of succinic was quantified. Significant correlation between operational factors and fermentation’s effluents was proved. Throughout changing simple operating parameters one could design process to produce desirable concentration and composition of VFAs.
Fluoroquinolones can be oxidized with some agents, in this study selected fluoroquinolones (levofloxacin, ofloxacin, ciprofloxacin, norfloxacin, pefloxacin and enrofloxacin) were oxidized with ...potassium bromate in the presence of terbium (III) ions. According to the kinetic and spectral analysis of chemiluminescence emitted by the above systems, the terbium (III) ions were the only emitter. The excitation of the lanthanide ion was a result of the process of energy transfer from the products of fluoroquinolones oxidation to Tb(III) ions. The highest intensity of chemiluminescence was obtained for levofloxacin and ofloxacin containing an alkoxy substituent at C‐8 in the quinoline ring. The chemiluminescence intensity was correlated linearly (r = 0.9994) with the concentration of ofloxacin (or levofloxacin) in the range 1 × 10−6 to 4 × 10−5 mol L−1; the detection limit was 3 × 10−7 mol L−1 for both fluoroquinolones. In the optimized conditions, the chemiluminescence of the levofloxacin (or ofloxacin)–Tb(III)–KBrO3–H2SO4 systems was used to determine these compounds in a mixture of fluoroquinolones and in pharmaceuticals.
● Terbium (III) ions as sensitizers of fluoroquinolone oxidation.● Chemiluminescence method for determination of levofloxacin and ofloxacin in pharmaceutical preparations and in a mixture of different fluoroquinolones.
Chemiluminescence (CL) generated in the process of oxidation of fluoroquinolones (FQ) in the reaction systems Fe(II)/(III)-H2O2 and KNO2-H2O2 in acidic environment, as the sources of reactive oxygen ...species, was studied. For all studied systems containing FQ (levofloxacin or enrofloxacin or pefloxacin) the kinetic curves of chemiluminescence decay were recorded and the emission obtained was subjected to spectral and kinetic analyses. Terbium(III) ions were used as sensitizers. A linear relation was found between the integral intensity of chemiluminescence (the area under the CL kinetic curve) and FQ concentration. The limits of detection for enrofloxacin, pefloxacin and levofloxacin were calculated to be 6 × 10−8 molL−1, 1.2 × 10−7 molL−1 and 9.4 × 10−7 molL−1, in the system FQ-Tb(III)-Fe(II)/(III)-H2O2 and 1.4 × 10−7 molL−1, 2.4 × 10−7 molL−1 and 1.4 × 10−6 molL−1, in the system FQ-Tb(III)-KNO2-H2O2. The recoveries were 96.7–102.5% for commercial formulations and urine samples and RSD was below 2.5%.
•Oxidation of fluoroquinolones in the systems generating reactive oxygen species.•Terbium(III) ions as sensitizers of fluoroquinolones oxidation.•Analytical application of the emission of FQ-Tb(III)-Fe(II)/(III)-H2O2 system.•Analytical application of the emission of FQ-Tb(III)-KNO2-H2O2 system.
A series of SiO2-La2O2CO3 and SiO2-La2O3 mixed oxide/carbonate systems with La/Si molar ratios of 0.05, 0.1, 0.25, 0.5 and 1.0 have been obtained by the sol–gel technique from tetraethyl ...orthosilicate (TEOS) and metallic lanthanum powder. For the low lanthanum loading systems (La/Si 0.05 to 0.25) the lanthanum carboxy phase is easily transformed to oxide phase during thermal treatment in the presence of silica. The most important advantage of the proposed method is the possibility of obtaining a mixed oxide/carbonate phase and not directly an oxide phase as in the case of other methods. Depending on the calcination temperature and time, the proposed method can be used for obtaining compositions containing dioxycarbonate, oxide or mixed lanthanum phase.
The systems were characterized by X-ray diffraction, low temperature nitrogen adsorption, transmission and scanning electron microscopy (TEM, SEM and SEM/EDS), thermogravimetric analysis (TGA), and FT-IR spectra.
•A new synthesis method of mixed oxide-carbonate SiO2-La2O3 and SiO2-La2O2CO3•Easy introduction of metal oxide precursors•One-pot synthesis
A series of mixed oxide‑carbonate Al2O3-La2O2CO3 systems with the La/Al molar ratios of 0.05, 0.1, 0.25, 0.5 and 1.0 have been synthesized by the sol–gel technique from aluminum isopropoxide and ...metallic lanthanum powder. During the synthesis of Al2O3- La2O2CO3 system, metallic lanthanum acts both as a precursor of lanthanum oxide and as secondary pH modifier of the gel solution. The traditional sol-gel method was modified to provide a better control over the final product surface parameters and structure. The obtained systems were amorphous and highly homogenic. The rate of the metal reaction was used as a limiting factor to control the gel formation. The obtained oxide systems are intended as a support for metallic phase catalysts. Calcination in air at 600°C did not produce systems containing only oxides and the lanthanum (dioxy)carbonate phase was still present. This observation can be explained by the multi stage decomposition process of lanthanum acetate forming during the gel synthesis.
The systems were characterized by X-ray powder diffraction, low temperature nitrogen adsorption, transmission and scanning electron microscopy (TEM, SEM and SEM/EDS), thermogravimetric analysis (TGA), and FTIR spectra.
•a new synthesis method of mixed oxide‑carbonate Al2O3-La2O2CO3 systems has been proposed•easy introduction of metal oxide precursors•one-pot synthesis – an improvement of sol-gel method
The aim of this work is to evaluate analytical tools for fast assessment of the catalysts’ ability to conduct a catalytic cracking process with the use of vegetable oils. The practical context of the ...presented concept relates to the use of cracking reaction products as valuable chemical raw materials. The proposed analytical tools allow for quick assessment of reaction products, indication of the molecular weight range, or the presence of specific functional groups. We want to emphasize that vegetable oils can not only be raw products for biofuels but also an alternative to petrochemicals. The study was undertaken to determine the influence of acid–base properties of catalysts on the rapeseed oil conversion process at 500°C. The effect of these properties on the character of the process and quality of the products obtained was shown to be very high. Basic correlations between the formation of coke, gaseous products and dehydrogenation products, and acid–base parameters of the individual catalysts have been observed. The use of spectroscopic methods (FTIR ‐ Fourier Transform Infrared Spectroscopy, 1H NMR ‐ Nuclear Magnetic Resonance) for fast qualitative analysis of the products is described.
A series of binary oxide systems with Ca/Si molar ratios of 0.05, 0.1, 0.25, 0.5 and 1.0 have been synthesized by the sol-gel technique from tetraethyl orthosilicate (TEOS) and metallic calcium ...powder. Upon calcination, a side effect of wollastonite formation as a result of the reaction between the components of the material has been observed in the two calcium-richest systems. The increase in calcium content produces an effect of porosity promotion. At high calcium contents, the homogeneity of the systems is limited by the ability of silica to disperse the calcium component. The properties of these systems are determined by the silica surface coverage with a large amount of the scattered CaCO3 fine microcrystallites (calcite), resulting from the phase segregation. The gels were characterized by X-ray powder diffraction, low temperature nitrogen adsorption, transmission and scanning electron microscopy (TEM, SEM and SEM/EDS), thermogravimetric analysis (TGA), and FT-IR spectra, to describe the parameters important from the point of view of their application as a support for metal-based catalysts.
A series of binary Al
2
O
3
–CaO and Al
2
O
3
–CaO–CaCO
3
systems with Ca/Al molar ratios of 0.05, 0.1, 0.25, 0.5 and 1.0 have been synthesised by the sol–gel technique from aluminium isopropoxide ...and metallic calcium powder. The rate of the metal reaction is used as a limiting factor to control the binary gel formation. The proposed modification of the traditional sol–gel method was used to examine the influence the effect of the metallic form of the second component as an oxide precursor on the form of the final product. By applying acetic acid instead of mineral acid, calcium acetate is formed and then decomposed to calcium carbonate upon thermal processing. During the synthesis of the binary systems, metallic calcium acts both as a precursor of calcium acetate and as a secondary pH modifier of the gel system. Calcination in air at 600 °C did not produce systems containing only oxides and the calcium carbonate phase was still present. Due to particle size reduction, the CaCO
3
to CaO decomposition temperature was lowered. The systems were characterised by X-ray powder diffraction, low-temperature nitrogen adsorption, transmission and scanning electron microscopy (TEM, SEM and SEM/EDS), thermogravimetric analysis (TGA) and FTIR spectra.
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