Comparative determination of lead concentrations in the air of the working environment by x-ray fluorescence spectroscopy and the spectrophotometric method

Za određivanje koncentracije olova u vazduhu u autoservisnoj radionici -Autovojvodina- u Novom Sadu primijenjene su metode rendgenske fluorescentne spektroskopije i spektrofotometrije. Rendgenski fluorescentni spektrometar baždaren je apliciranjem poznatih koncentracija Pb(N03)i na filter-papir. Vazduh je uzorkovan filtracijom poznatog volumena kroz filter-papir. Nađena koncentracija olova u vazduhu bila je ispod maksimalne dozvoljene koncentracije. U radu su izneseni i rezultati dobiveni spektrofotometrijskom metodom te su nađene razlike od 10 do 30% u odnosu na rezultate dobivene rendgenskom fluorescentnom spektroskopijom.The x-ray fluorescence spectroscopy and the spectrophotometric method were used to determine lead concentrations in the air of an auto repair shop. The calibration of the x-ray spectrometer was performed with known concentrations of water solutions of Pb(N03), on filter paper. Samples were prepared by filtration of measured volumes of air. The lead amounts determined were below the maximum permissible concentrations. The results obtained with the spectrophotometric method are also given showing discrepancies between 10 and 30 per cent if compared with the results of x-ray fluorescence spectroscopy

Optical amplification and stability of spiroquaterphenyl compounds and blends

In this contribution, we present a systematic investigation on a series of spiroquaterphenyl compounds optimised for solid state lasing in the near ultraviolet (UV). Amplified spontaneous emission (ASE) thresholds in the order of 1 μJ/cm^2 are obtained in neat (undiluted) films and blends, with emission peaks at 390±1 nm for unsubstituted and meta-substituted quaterphenyls and 400±4 nm for para-ether substituted quaterphenyls. Mixing with a transparent matrix retains a low threshold, shifts the emission to lower wavelengths and allows a better access to modes having their intensity maximum deeper in the film. Chemical design and blending allow an independent tuning of optical and processing properties such as the glass transition

A kinetic and thermodynamic investigation into the removal of methyl orange from wastewater utilizing fly ash in different process configurations

The removal of methyl orange using coal fly ash, which is a widely available low-cost adsorbent, has been investigated. Adsorption studies for dye removal were conducted using various configurations such as batch, column and heap adsorption at various temperatures and adsorbent dosages at neutral pH. The Langmuir, Freundlich and Tempkin isotherm models were used to describe the process. The Freundlich model best represented the adsorption. Kinetic studies show the adsorption followed pseudo-second-order kinetics. Thermodynamic studies show that the process is spontaneous, endothermic and random. Column configuration was found to be the most efficient with a dye removal percentage of 99.95%, followed by heap adsorption at 99.25% removal and lastly batch configuration with 96.68% removal. Economic analysis shows that column operation would be the most effective for practical implementation

Metal concentration and particle size distribution of stream and river water polluted from copper rolling mill industry

Concentrations of heavy metals, pH, and particle size distribution parameters were measured in Dragica stream and Djetinja River water receiving wastewaters from copper rolling mill industry, Sevojno. The concentrations of copper, zinc, lead, and mercury were determined for water samples collected in summer 2009. It was found that Copper Rolling Mill Sevojno was the significant source of water pollution with copper and zinc. Considering that copper rolling mill industry, one of the larger emitters of sulfur dioxide, pollutes the area, the water pH was surprisingly alkaline. The particle size analysis results showed that particles from oil-in-water emulsion evidently got into stream water in spite of the purification devices used. In order to assess the possible relations between the measured parameters, a correlation analysis was performed. The correlation analysis showed a significant positive correlation between the total metal concentrations of copper and zinc, as well as between particle size distribution parameters and the concentration of lead and copper

Optical amplification and stability of spiroquaterphenyl compounds and blends

Gefördert durch den Publikationsfonds der Universität Kasse