1. The effects of ozone sterilization on the chemical and mechanical properties of 3D-printed biocompatible PMMAIvan Morosavljević, Dražan Kozak, Tihomir Kosor, Janko Morosavljević, Luka Ferlič, Nenad Gubeljak, 2024, original scientific article Abstract: Since ozone is highly corrosive, it can substantially affect the mechanical and chemical properties of the materials; consequently, it could affect the applicability of those materials in medical applications. The effect of ozone sterilization on the chemical and mechanical properties of additively manufactured specimens of biocompatible poly(methyl-methacrylate) was observed. FDM 3D-printed specimens of biocompatible PMMA in groups of five were exposed to high concentrations of ozone generated by corona discharge for different durations and at different ozone concentrations inside an enclosed chamber with embedded and calibrated ozone, temperature, and humidity sensors. A novel approach using laser-induced fluorescence (LIF) and spark-discharge optical emission spectrometry (SD-OES) was used to determine an eventual change in the chemical composition of specimens. Mechanical properties were determined by testing the tensile strength and Young’s modulus. A calibrated digital microscope was used to observe the eventual degradation of material on the surface of the specimens. SD-OES and LIF analysis results do not show any detectable sterilizationcaused chemical degradation, and no substantial difference in mechanical properties was detected. There was no detectable surface degradation observed under the digital microscope. The results obtained suggest that ozone sterilization appears to be a suitable technique for sterilizing PMMA medical devices.
Keywords: ozone sterilization, poly(methyl-methacrylate) (PMMA), polymer oxidation, personalized medical device, environmentally friendly, fused deposition modeling (FDM)
Published in DKUM: 30.07.2025; Views: 0; Downloads: 1
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2. Ozonation of amoxicillin and ciprofloxacin in model hospital wastewater to increase biotreatabilitySeverina Aleksić, Andreja Žgajnar Gotvajn, Katarina Premzl, Mitja Kolar, Sonja Šostar-Turk, 2021, original scientific article Abstract: Amoxicillin (AMX) and Ciprofloxacin (CIP) are antibiotics commonly used in human medicine with high environmental toxicity and poor biodegradability. They have been found in various hospital effluents and groundwater, and their environmental impact is still not fully understood. In this work, we investigated the possibility of treating model wastewaters containing the antibiotics AMX and CIP using ozonation, with the addition of H$_2$O$_2$ under various conditions, including different pH values, H$_2$O$_2$, and ozone dosages. The quantification of and treatment efficacy for antibiotic removal were determined via solid phase extraction followed by chromatographic separation by liquid chromatography coupled with tandem triple quadrupole mass spectrometry (LC/MS/MS). This analytical system is quite efficient for the detection of all major antibiotic classes, even if they are present at very low concentrations. The efficiency of ozonation was determined by measuring the TOC (Total Organic Carbon) changes after ozonation of the model wastewater and by measuring the concentration of the two antibiotics. In a sequential activated sludge process of ozone-treated model wastewater, almost complete TOC removal and an overwhelming decrease in antibiotic concentrations (up to 99%) were observed. Ozonation resulted in complete removal of AMX and CIP in less than 30 and 120 min, respectively. The results of this work indicate that ozonation could be a suitable pretreatment method to reduce the toxicity of contaminants (AMX and CIP) and improve the biodegradability of hospital wastewater.
Keywords: antibiotics, amoxicillin, AMX, ciprofloxacin, CIP, hospital wastewater, hydrogen peroxide, ozone, sludge, water treatment
Published in DKUM: 06.08.2024; Views: 75; Downloads: 16
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3. Depleting state of stratospheric ozone : a challenging conservation for global community with special reference to EritreaMohammad Afsar Alam, 2016, review article Abstract: Though the basic needs of the humans are prioritized first, health and quality of environment are also equally important. Environmental issues are based on many and different things. One of these is the depleting state of Stratospheric Ozone in the atmosphere. The ozone layer is vital to life on earth because it acts as a filter for UV radiation, which can have severe impacts on human health and the earth’s environment. As estimated, every one per cent decrease in the ozone layer results in the increase of ultraviolet light intensity at the earth's surface by two per cent. Known effects of ultraviolet exposure include greater incidence of skin cancer and eye cataracts among humans and diminished crop yields for foods such as peas, beans, and squash and soya beans. Phytoplankton, the tiny one celled Ocean plants that are staple food for squid, fish, seals, and whales also are vulnerable to Ultra violet radiations. Depletion of ozone layer is one of the main issues of the world today. Concerning to these issue two important meetings had been hold i.e. known by the Montreal Protocol and Vienna Convention. Most of the world countries are part of this Montreal Protocol and Vienna Convention. Eritrea is also part of Montreal Protocol and Vienna Convention. In the present paper basically an attempt has been made to show the world’s concern in general and the Eritrea’s in particular about the conservation measures taken on mitigation of Ozone layer. This research paper also emphasizes on the global problem of Ozone Depleting Substances (ODSs) releasing from different industries and specific sources. Besides, the study further includes the existence of naturally created Ozone hole on the Polar Regions.
Keywords: ozone layer, depletion, chlorofluorocarbons, CFCs, environment
Published in DKUM: 17.04.2018; Views: 1507; Downloads: 101
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4. Kinetic studies of catalytic ozonation of atrazineBrigita Tepuš, Marjana Simonič, 2008, original scientific article Abstract: The aim of our work was to degrade atrazine by the ozone treatment of both a model and the original drinking water samples, using Pt-catalyst, and to evaluate the performance of this catalyst. The rate constant for the reaction of atrazine with ozone was determined in the model water sample. The activation energies and the reaction orders of ozone decomposition were determined in both the model and the drinking water samples. Ozone treatment using Pt-catalyst has some influence on the loss of atrazine in the sources of drinking water. The concentration of some metabolites in the model and drinking water was observed during ozone treatment. The toxicity of atrazine to crustacean Daphnia magna in the original drinking water and in the ozone treated water samples was also assessed.
Keywords: ozone, Pt-catalyst, atrazine, water treatment, waste water, kinetics
Published in DKUM: 05.07.2017; Views: 1352; Downloads: 88
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5. Comparison of H2O2/UV, H2O2/O3 and H2O2/Fe2+ processes for the decolorisation of vinylsulphone reactive dyesTanja Kurbus, Alenka Majcen Le Marechal, Darinka Brodnjak-Vončina, 2003, original scientific article Abstract: Six vinylsulphone reactive dyes were decolorised using three oxidation processes (H2O2/UV, H2O2/O3 and H2O2/Fe2+). The efficiency of decolorisation was measured by decolorisation time, absorbance, COD and TOC and the three methods of decolorisation are compared.
Keywords: textile reactive dyes, vinylsulphone dyes, decolorisation, hydrogen peroxide, UV irradiation, ozone, Fenton's reagent, pollution parameters, experimental design
Published in DKUM: 01.06.2012; Views: 2182; Downloads: 107
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