Szkoła doktorska

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https://oa.zut.edu.pl/handle/20.500.12539/14

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Przeglądaj Szkoła doktorska wg Autor "Rakoczy, Rafał"

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  • Miniatura
    PozycjaOpen Access
    A new magnetic-hybrid photoreactor for photocatalytic water disinfection
    (Polska Akademia Nauk, 2023-07-14) Paszkiewicz, Oliwia; Wang, Kunlei; Kordas, Marian; Rakoczy, Rafał; Kowalska, Ewa; Markowska-Szczupak, Agata; West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, Piastow 42, 71-065 Szczecin, Poland; Hokkaido University, Institute for Catalysis (ICAT), N21, W9, 001-0021 Sapporo, Japan; West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, Piastow 42, 71-065 Szczecin, Poland; West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, Piastow 42, 71-065 Szczecin, Poland; Hokkaido University, Institute for Catalysis (ICAT), N21, W9, 001-0021 Sapporo, Japan; Jagiellonian University, Faculty of Chemistry, Gronostajowa 2, 30-387 Krakow, Poland; West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, Piastow 42, 71-065 Szczecin, Poland
    In this research, the removal of model gram-negative bacteria Escherichia coli and gram-positive Staphylococcus epidermidis bacteria from aqueous solutions using copper-modified titania 0.5Cu@HomoP25, 2.0Cu @HomoP25, 5.0Cu@HomoP25 in new hybrid photoreactor assisted with rotating magnetic field (RMF) was evaluated. Therefore, the analysis of variance (ANOVA) test was employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as copper concentration [% w/w], time [h] and frequency of RMF [Hz] were studied. Results: Analysis of variance (ANOVA), revealed a good agreement between experimental data and the proposed quadratic polynomial model (R2=0.86 for E. coli and R2=0.69 for S. epidermidis). Experimental results showed that with increasing copper concentration, time, and decreasing frequency of RMF removal efficiency was increased. Accordingly, the water disinfection efficiency of 100% in the regression method of the independent variables: for E. coli bacteria: c = 5 %; t = 3 h; f = 50 Hz, and for S. epidermidis c = 2.5 %; t = 1.3 h; f = 26.6 Hz were optimized. This study showed that the nonlinear regression method is a useful tool for optimizing the operating parameters for the photocatalytic disinfection process.
  • Miniatura
    PozycjaOpen Access
    Antimicrobial properties of pristine and Pt-modified titania P25 in rotating magnetic field conditions
    (Elsevier B.V., 2022-08-01) Paszkiewicz, Oliwia; Wang, Kunlei; Rakoczy, Rafał; Kordas, Marian; Leniec, Grzegorz; Kowalska, Ewa; Markowska-Szczupak, Agata; Department of Chemical and Process Engineering, West Pomeranian University of Technology in Szczecin, Piastow 42, Szczecin 71-065, Poland; Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan; Institute of Physics, Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, al. Piastow 48, Szczecin 70-311, Poland; Department of Chemical and Process Engineering, West Pomeranian University of Technology in Szczecin, Piastow 42, Szczecin 71-065, Poland; Institute of Physics, Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, al. Piastow 48, Szczecin 70-311, Poland; Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan; Department of Chemical and Process Engineering, West Pomeranian University of Technology in Szczecin, Piastow 42, Szczecin 71-065, Poland
    Effective and cheap water purification is one of the most important tasks facing humanity. Among various methods of water treatment, heterogeneous photocatalysis is probably most recommended. However, the application of artificial sources of irradiation results in high investment and operating costs. Accordingly, either vis-responsive photocatalysts or different ways of photocatalyst activation should be developed. In the present study, rotating magnetic field (RMF) has been tested to inactivate gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria in the presence of pristine and Pt-modified titania P25 photocatalyst. Liquid cultures of the bacteria have been exposed to the titania and RMF (RMF frequency of 1–50 Hz, RMF magnetic induction of ca. 19.92 mT, 180 min exposure time, temperature of incubation at 37 °C). It has been found that highly active titania photocatalyst might also work in the absence of photoirradiation but under RMF. Moreover, its modification with platinum besides highly improved photocatalytic activity (tested for two model reactions of oxidative decomposition of acetic acid and anaerobic dehydrogenation of methanol under UV/vis irradiation) results in significant enhancement of antimicrobial effect under RMF. Additionally, photocatalysts with larger content of oxidized forms of platinum show higher antimicrobial activity, and thus it is proposed that platinum oxides are more active than zero-valent platinum under RMF. This study provides evidence of antimicrobial effect of titania without photoirradiation, indicating that RMF might efficiently activate photocatalyst.