Biomedical subjects

Natalija Koprivanac

Publications and source records attributed to Natalija Koprivanac.

6 recordsLinked to original sources

PubMed2006

Fe-exchanged zeolite as the effective heterogeneous Fenton-type catalyst for the organic pollutant minimization: UV irradiation assistance.

The issue of investigations in this study was an application of heterogeneous Fenton-type catalyst, Fe-exchanged zeolite FeZSM5, for the minimization of phenol and overall organic content in the model wastewater. Applied treatment systems included variation of heterogeneous and homogeneous Fenton-type catalyst with and without the assistance of UV irradiation, FeZSM5/H2O2, Fe2+/H2O2/NH4ZSM5, Fe3+/H2O2/NH4ZSM5, UV/FeZSM5/H2O2, UV/Fe2+/H2O2/NH4ZSM5 and UV/Fe3+/H2O2/NH4ZSM5. Processes efficiency was evaluated on the basis of phenol removal, mineralization extent, H2O2 consumption and concentration of iron ions in the bulk after the treatment. By all applied systems, complete phenol removal was achieved in less than 30 min of treatment time. Systems including heterogeneous Fenton-type catalyst showed somewhat lower mineralization efficiency in comparison to the corresponding systems applying homogeneous Fenton-type catalysts and the addition of synthetic zeolite NH4ZSM5. Significantly lower concentration of iron ions in the bulk after the treatment could give these systems, particularly UV/FeZSM5/H2O2, a great advantage over the homogeneous Fenton-type systems.

Catalysis↗

PubMed2006

Photo-assisted Fenton type processes for the degradation of phenol: a kinetic study.

In this study the application of advanced oxidation processes (AOPs), dark Fenton and photo-assisted Fenton type processes; Fe(2+)/H(2)O(2), Fe(3+)/H(2)O(2), Fe(0)/H(2)O(2), UV/Fe(2+)/H(2)O(2), UV/Fe(3+)/H(2)O(2) and UV/Fe(0)/H(2)O(2), for degradation of phenol as a model organic pollutant in the wastewater was investigated. A detail kinetic modeling which describes the degradation of phenol was performed. Mathematical models which predict phenol decomposition and formation of primary oxidation by-products: catechol, hydroquinone and benzoquinone, by applied processes were developed. The study also consist the modeling of mineralization kinetic of the phenol solution by applied AOPs. This part, besides well known reactions of Fenton and photo-Fenton chemistry, involves additional reactions which describe removal of iron from catalytic cycle through formation of ferric complexes and its regeneration induced by UV radiation. Phenol decomposition kinetic was monitored by HPLC analysis and total organic carbon content measurements (TOC). Complete phenol removal was obtained by all applied processes. Residual TOC by applied Fenton type processes ranged between 60.2 and 44.7%, while the efficiency of those processes was significantly enhanced in the presence of UV light, where residual TOC ranged between 15.2 and 2.4%.

Algorithms↗

PubMed2006

UV-based processes for reactive azo dye mineralization.

In the present study, advanced oxidation processes, UV/H2O2, UV/O3, and UV/H2O2/O3 have been applied to bleach and degrade organic dye C.I. Reactive Red 45 in water solution. Influence of pH and hydrogen peroxide dosage on process efficiency was investigated. The rate of color removal was studied by measuring the absorbance at the characteristic wavelength while mineralization rates were obtained on the basis of total organic carbon (TOC) and adsorbable organic halides (AOX) measurements. Complete bleaching was achieved by all applied processes after 60 min while the maximal mineralization extent depended on the reaction conditions for each of the processes. It has been found that UV/H2O2/O3 process was the most efficient with 61.1% TOC removal and 72.0% AOX removal, respectively, achieved after a 1-h treatment. Time required for complete mineralization of RR45 by UV/H2O2 and UV/H2O2/O3 processes was determined as well.

Azo Compounds↗

PubMed2006

Advanced oxidation processes in azo dye wastewater treatment.

The chemical degradation of synthetic azo dyes color index (C.I.) Acid Orange 7, C.I. Direct Orange 39, and C.I. Mordant Yellow 10 has been studied by the following advanced oxidation processes: Fenton, Fenton-like, ozonation, peroxone without or with addition of solid particles, zeolites HY, and NH4ZSM5. Spectrophotometric (UV/visible light spectrum) and total organic carbon measurements were used for determination of process efficiency and reaction kinetics. The degradation rates are evaluated by determining their rate constants. The different hydroxyl radical generation processes were comparatively studied, and the most efficient experimental conditions for the degradation of organic azo dyes solutions were determined.

Azo Compounds↗

PubMed2005

Decomposition of phenol by hybrid gas/liquid electrical discharge reactors with zeolite catalysts.

Application of hybrid gas/liquid electrical discharge reactors and a liquid phase direct electrical discharge reactor for degradation of phenol in the presence and absence of zeolites have been investigated. Hybrid gas/liquid electrical discharges involve simultaneous high voltage electrical discharges in water and in the gas phase above the water surface leading to the additional OH radicals in the liquid phase and ozone formation in the gas phase with subsequent dissolution into the liquid. The role of applied zeolites, namely NH4ZSM5, FeZSM5 and HY, were also studied. Phenol degradation and production of primary phenol by-products, catechol and hydroquinone, during the treatment were monitored by HPLC measurements. The highest phenol removal results, 89.4-93.6%, were achieved by electrical discharge in combination with FeZSM5 in all three configurations of corona reactors. These results indicate that the Fenton reaction has significant influence on overall phenol removal efficiency in the electrical discharge/FeZSM5 system due to the additional OH radical formation from hydrogen peroxide generated by the water phase discharge.

Catalysis↗

PubMed2005

Influence of iron on degradation of organic dyes in corona.

In this work application of AOPs such as Fenton process, aqueous phase high voltage electrical discharge (corona) and their combination have been studied for colored wastewater treatment. Experiments were conducted on water solutions of four different organic dyes, two azo dyes C.I. Mordant Yellow 10 (MY10) and C.I. Direct Orange 39 (DO39), and two reactive of azo type C.I. Reactive Red 45 (RR45) and C.I. Reactive Blue 137 (RB137). The efficiency of studied AOPs has been estimated on the bases of UV-vis spectrophotometric and TOC measurements. The rate constants in the kinetic model have been determined. Experimental data have been compared with the developed mathematical model.

Coloring Agents↗