Alapi, Tünde

Farkas, Luca

Varga, Virág

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 II                              INTERNATIONAL CONFERENCE ON ENERGY, ENVIRONMENT AND STORAGE OF ENERGY ICEESEN 2020 Conference Proceedings 19th – 21th of November 2020 Kayseri, Turkey  Editor in Cheif Prof. Dr. Selahaddin Orhan Akansu  Co-Editor Prof. Dr. Sebahattin Unalan  Proceedings of ICEESEN2020, 19-21 November 2020, Kayseri-Turkey 351  THE COMPARISON OF THE EFFICIENCY OF LOW-PRESSURE MERCURY VAPOUR LAMP AND XENON EXCIMER LAMP IN THE VUV PHOTOLYSIS OF SULFONAMIDE ANTIBIOTICS Luca Farkas, Virág Varga and Tünde Alapi 1. University of Szeged, Faculty of Science and Informatics, Department of Inorganic and Analytical Chemistry, Szeged, Dóm square 7.  Abstract VUV radiation (   200 nm) generates reactive HO• and H• directly from the water without addition of any oxidizing agents. Two VUV light source was investigated and compared for the removal of sulfonamide antibiotics, as hazardous substances, from aqueous solution. The low-pressure mercury vapour lamp, emits 254 nm UV and 185 nm VUV light, is a commonly used to produce high-purity water. The other light source was a Xenon excimer lamp, which emits 172 nm VUV light. Although the photon flux of 172 nm VUV light was about five times higher than that of 185 nm VUV light, the formation rate of H2O2 in pure water was 40 times higher in the case of Xe excimer lamp. Transformation rate of antibiotics (sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfadimethoxine) were investigated and compared in the case of their four-components solutions. The effect of three different matrices (tap water, purified industrial wastewater and biologically treated domestic wastewater) were examined on the transformation rate of organic substances. The higher photon flux of 172 nm light did not cause much better efficiency, and proved to be more sensitive for the matrix parameters than UV/VUV185nm radiation. It can be explained by the extreme inhomogeneity of 172 nm radiated solution. Keywords: VUV photolysis, Sulfonamide, AOP 1 INTRODUCTION Advanced Oxidation processes (AOPs) applied to oxidize harmful organic substances, which are difficult to degrade by traditional biological water treatment methods. VUV photolysis, one of the AOPs, is based on high-energy (wavelength <200 nm) radiation, which is able to cause the dissociation of water molecules and produce HO• and H•. During VUV photolysis, the reactive species are formed directly from the photolysis of water without any addition of oxidizing agents.  The molar absorbance of water highly depends on the wavelength: 185 nm photons are absorbed within 11 mm thin water layer, while 172 nm VUV photons are absorbed within 0.04 mm. This extreme inhomogeneity has several consequences. 2 EXPERIMENTAL For the 172 nm radiation (VUV172nm) Xe2* excimer light source was used. The lamp (Radium XeradexTM, 130 mm long, 46 mm diameter, 20 W) was centred in a high purity silica quartz envelope. For the UV/VUV185nm (254 nm/185 nm) radiation a low-pressure mercury vapour (LP) lamp (227 mm arc length, produced by LightTech) was used. This lamp’s envelope was made of synthetic quartz. Separation of the aromatic components in the treated solutions was performed by Agilent 1100 type HPLC equipped with diode array detector (DAD). For the sulfonamides (sulfamethazine (SMT), sulfamethoxypyridazine (SMP), sulfachloropyridazine (SCP), sulfadimethoxine (SDM)) analysis, Lichrospher 100, RP-18; 5 μm column was used, thermostated at 30 °C, with 1.0 mL min-1 flow rate of eluent, and 20 μL sample was injected. 3 RESULTS AND DISCUSSION During the VUV172nm photolysis of Milli-Q water, HO• and H• are formed as primary species. Without organic substances, the recombination of HO• radicals result in the formation of H2O2. In the presence of dissolved O2, another way is the recombination of less reactive HO2• and O2•¬ (Figure 1.) In 172 nm radiated water about 40 times more H2O2 formed than in UV/VUV185 nm radiated one, despite, that the ratio of photon fluxes is around 5 (VUV172 nm: 3×10-6 molphoton s−1; VUV185 nm: 5-7×10-7 molphoton s−1). In O2-free solution, H2O2 is formed in significant concentration only in the case of VUV photolysis, its value is almost a quarter of the value measured in O2-saturated solution.     Proceedings of ICEESEN2020, 19-21 November 2020, Kayseri-Turkey 352            Figure 1. The concentration of H2O2 versus the time of irradiation in the case of UV/VUV185nm and VUV172nm photolysis            Figure 2. The transformation rates of one-component (2.0×10-5 M) containing solutions and four-component (2.0×10-5 M of each sulfonamide) solutions  As Figure 2. shows, UV photolysis has significant contribution to the transformation in UV/VUV185nm radiated solutions. In the case of four-component mixtures, the transformation rate of each sulfonamide was reduced to 40–25% (Figure 2.), which can be explained by competition for HO  radicals. Despite the significantly higher photon flux, similar transformation rates were measured in solutions radiated with 172 nm light and in those radiated with 254/185 nm light. The volume of the treated solutions was the same (500 mL). AOPs are generally used as post-treatment method in water treatment, thus it is important to investigate the effect of different type of water matrix on the transformation of harmful substances. Three different type of matrices were investigated in this study: tap water having high ionic content (conductivity: 627 S cm-1) and low organic content (COD: 0.79 mg L-1), RO purified industrial wastewater (COD: 0.11 mg L-1) and biologically treated domestic wastewater (conductivity: 1258 S cm-1 COD: 6.9 mg L-1) (Figure 3.).              Figure 3. The effect of matrices UV/VUV (a) and VUV (b) photolysis  During UV/VUV photolysis, tap water had a positive effect in the case of SMT, while it has a negative effect in the case of SCP and SDM). In the case of VUV photolysis its effect is negligible. The RO-treated industrial water has no effect in the case of VUV172nm photolysis, while biologically treated one strongly decreased the transformation rates. This is mainly due to the higher COD value and relative high HCO3- (103.4 mg L-1) concentration.  Electrical Energy per Order (EEO) were calculated and compared in each case. When biologically treated domestic water was used as matrix, the EEO values were significantly higher for Xenon-excimer lamp. The higher photon flux of 172 nm light did not resulted in much better efficiency, and proved to be more sensitive for the matrix parameters than UV/VUV185nm radiation. It can be explained by the extreme inhomogeneity of 172 nm radiated solution.  ACKNOWLEDGEMENTS This publication was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, and new national excellence program of the Ministry for Innovation and Technology (ÚNKP-20-3-SZTE-459 and ÚNKP-20-5-SZTE-639). The authors thanks the financial support from the project Hungarian Scientific Research Fund (NKFI contract number FK132742) 0.02.04.06.08.010.00.02.04.06.08.010.00 30 60 90c (H2 O2 ) (×10-6M)c (H2O2) (×10-5M)t (min)VUV, O2VUV, N2UV/VUV, O2UV/VUV, N20.00.51.01.52.02.53.0SMT SP SCP SDMr 0(×10-8M/s)MQ tap waterRO wastewater biol. wastewater0.00.51.01.52.02.53.03.5SMT SP SCP SDMr 0(×10-8M/s)MQ tap waterRO wastewater biol. Wastewatera                                   b 0.02.04.06.08.010.0SMT SMP SCP SDMr 0(×10-8M s-1 )VUV VUV mixUV/VUV UV/VUV mixUV

The comparison of the efficiency of low-pressure mercury vapour lamp and xenon excimer lamp in the VUV photolysis of sulfonamide antibiotics

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The comparison of the efficiency of low-pressure mercury vapour lamp and xenon excimer lamp in the VUV photolysis of sulfonamide antibiotics

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