Gyuri Sági
Hungarian Academy of Sciences
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Gyuri Sági.
Journal of Pharmaceutical and Biomedical Analysis | 2015
Gyuri Sági; Tamás Csay; László Szabó; György Pátzay; Emil Csonka; Erzsébet Takács; László Wojnárovits
By combining a large variety of analytical techniques this study aimed at elaborating methods to follow up the degradation of sulfonamides in an advanced oxidation process (AOP): irradiation with ionizing radiation in dilute aqueous solution. In this process, besides other radicals, hydroxyl radicals are produced. As pulse radiolysis experiments show the basic initial reaction is hydroxyl radical addition to the benzene ring, forming cyclohexadienyl radical intermediates. In aerated solutions these radicals transform to peroxy radicals. Among the first formed products aromatic molecules hydroxylated in the benzene rings or in some cases in the heterocyclic rings were observed by LC-MS/MS. Chemical oxygen demand (COD) measurements indicate that at the early reaction period of degradation one hydroxyl radical induces incorporation of 1.5 O atoms into the products. Comparison of the COD and TOC (total organic carbon content) results shows gradual oxidation. Simultaneously with hydroxylation ring opening also takes place. The kinetics of inorganic SO4(2-) and NH4(+) formation, analyzed by ion chromatography, is similar to the kinetics of ring degradation (UV spectroscopy), however, there is a delayed formation of NO3(-). The latter ions may be produced in oxidative degradation of smaller N containing fragments. The S atoms of the sulfonamides remain in the solution (ICP-MS measurements) after degradation, whereas some part of the N atoms leaves the solution probably in the form of N2 (total nitrogen content (TN) measurements). Degradation is accompanied by a high pH drop due to formation of SO4(2-), NO3(-) and smaller organic acids. The degradation goes through many simultaneous and consecutive reactions, and with the applied methods the different stages of degradation can be characterized.
Science of The Total Environment | 2018
Gyuri Sági; Anikó Bezsenyi; Krisztina Kovács; Szandra Klátyik; Béla Darvas; András Székács; Csilla Mohácsi-Farkas; Erzsébet Takács; László Wojnárovits
Numerous studies have been published on the radiolysis of sulfonamide antibiotic solutions but little effort has been made to monitor the biological properties of degradation products. A complex approach should also clarify the changes in antibacterial activity and biodegradability, besides the usual screening of toxicity. To fill this gap, the ionizing radiation induced degradation of four sulfonamide antibiotics was investigated in dilute aqueous solutions, with emphasis on the biological assessment of decomposition products. Complete removal of sulfonamides was achieved by a low absorbed dose (1.5kGy). 2-2.5kGy dose was needed to transform the persistent initial molecules to substances biodegradable in both river water and activated sludge. The ratio of the biological and chemical oxygen demand increased from <0.21 to at least 0.59, but values as high as 0.80 were also measured. It was demonstrated that antibacterial activity is due to the initial molecules, as it disappeared when the sulfamethoxazole concentration decreased below the minimal inhibitory concentration (30 μM). This means that the products have no antibacterial activity. Toxicity testing performed on test organisms from three different trophic levels and activated sludge evidenced that the toxicity depends both on the test organism and on the sulfonamide used. The degradation of initial molecules is not always enough to eliminate the environmental risk due to the toxic products formed e.g. inhibitory effects to Vibrio fischeri increased by 34% at 2.5kGy. For this reason, complex biological assessment of treated solutions has to play an important role in development and optimization of advanced treatment techniques.
Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering | 2018
Gyuri Sági; K. Szabacsi; László Szabó; Renáta Homlok; Krisztina Kovács; Csilla Mohácsi-Farkas; Shiv Pillai; Erzsébet Takács; László Wojnárovits
ABSTRACT The response of the antimicrobial compounds sulfamethoxazole (SMX) and trimethoprim (TMP) – individually and in mixtures – to ionizing radiation was investigated using laboratory prepared mixtures and a commercial pharmaceutical formulation. The residual antibacterial activity of the solutions was monitored using Staphylococcus aureus and Escherichia coli test strains. Based on antibacterial activity, SMX was more susceptible to ionizing radiation as compared to TMP. The antibacterial activity of SMX and TMP was completely eliminated at 0.2 kGy and 0.8 kGy, respectively. However, when SMX and TMP were in a mixture, the dose required to eliminate the antibacterial activity was 10 kGy, implying a synergistic antibacterial activity when these are present in mixtures. Only when the antibiotic concentration was below the Minimum Inhibitory Concentration of TMP (i.e., 2 µmol dm–3) did the antibacterial activity of the SMX and TMP mixture disappear. These results imply that the synergistic antimicrobial activity of antimicrobial compounds in pharmaceutical waste streams is a strong possibility. Therefore, antimicrobial activity assays should be included when evaluating the use of ionizing radiation technology for the remediation of pharmaceutical or municipal waste streams.
Radiation Physics and Chemistry | 2016
Gyuri Sági; Krisztina Kovács; Anikó Bezsenyi; Tamás Csay; Erzsébet Takács; László Wojnárovits
Journal of Radioanalytical and Nuclear Chemistry | 2014
Gyuri Sági; Tamás Csay; György Pátzay; Emil Csonka; László Wojnárovits; Erzsébet Takács
Journal of Industrial and Engineering Chemistry | 2017
Erika Szabados; Gyuri Sági; Ferenc Somodi; Boglárka Maróti; Dávid Srankó; Antal Tungler
Radiation Physics and Chemistry | 2018
Gyuri Sági; Anikó Bezsenyi; Krisztina Kovács; Szandra Klátyik; Béla Darvas; András Székács; László Wojnárovits; Erzsébet Takács
Radiation Physics and Chemistry | 2017
Erzsébet Illés; Anna Tegze; Krisztina Kovács; Gyuri Sági; Zoltán Papp; Erzsébet Takács; László Wojnárovits
Radiation Physics and Chemistry | 2017
Krisztina Kovács; Gyuri Sági; Erzsébet Takács; László Wojnárovits
Reaction Kinetics, Mechanisms and Catalysis | 2015
Erika Szabados; Gyuri Sági; András Kovács; Erzsébet Takács; László Wojnárovits; Antal Tungler