ORALS

SESSION: PhysicalSatPM2-R10	Vayenas International Symposium on Physical Chemistry and its applications for sustainable development
Sat Oct, 26 2019 / Room: Aphrodite B (100/Gr. F)
Session Chairs: Renat Sultanov; Libor Kvitek; Session Monitor: TBA

17:10: [PhysicalSatPM212]
Hydrogenation of Carbon Dioxide on the Iron Based Nanocatalyst
Libor Kvitek¹ ; Martina Kubikova¹ ; Robert Prucek² ; Ales Panacek² ; Manoj B. Gawande¹ ; ¹Palacky University in Olomouc, Olomouc, Czech Republic; ²Palacky University, Olomouc, Czech Republic;
Paper Id: 274 [Abstract]

Global warming triggered by growing of the greenhouse gases concentration in the atmosphere actually represents the biggest world ecology problem. Carbon dioxide is one of the most important greenhouse gases because it is the main reason for global warming [1] Therefore, effective solutions to the global warming problem should be connected with the lowering of the carbon dioxide concentration in the atmosphere. One of the feasible protocols is to employ carbon dioxide as starting material and to convert it to the valuable compounds in various industrial processes which are very important. [2] For this purpose, iron-based materials act as a one of the most effective catalytic materials for carbon dioxide hydrogenation to methane, methanol and other simple important hydrocarbons. [3] Heterogeneous catalysis is connected with the active surface of catalysts. Therefore, the subject of the presented study is to investigate the influence of the catalyst’s physical state on its activity in hydrogenation of CO₂. Four types of iron oxide catalysts were prepared by high temperature decomposition of Iron (II) oxalate in the air. Afterword, its catalytic performance was studied at low pressure (1 bar) and low temperature (325°C) in the microreactor, Microactivity Effi, connected with a gas chromatograph for the detection of the reaction products. Depending on the order and rate of reaction, components mixing four different samples of the nanostructured iron oxide catalyst were prepared. After high temperature decomposition the composition of the prepared catalyst was determined by XRD and only hematite and magnetite in a various ratio between 90:10 down to 40:60 (hematite: magnetite) was observed in the emerging catalysts. Bigger differences between these catalysts were observed during reduction of the iron oxide in the hydrogen atmosphere by the XRD technique. Part of the samples produced zero valent iron but the second parts of the samples were reduced only to the form of pure magnetite. Also, observed catalytic activity of the prepared catalysts was different. The highest reaction rate, but also the lowest stability, was observed for catalysts which were reduced in the hydrogen atmosphere to zero valent irons, whereas catalysts which were reduced only to magnetite were substantially stable in selectivity of the production of methane in comparison with carbon monooxide. Unfortunately, total reaction rate was, in this case, slower. On the other hand, microstructured commercial Iron(II) oxide used as reference did not produce hydrocarbons (mainly methane), only carbon monoxide was observed as a carbon based product with this catalyst.

References:
References:\n[1] M. Aresta, A. Dibenedetto, Dalton Trans. 28 (2007) 2975-2992.\n[2] A. Rafiee, R. Khalilpour, D. Milani, M. Panahi, J. Environ. Chem. Eng. 6 (2018) 5771-5794.\n[3] C.-S.T. Chih-Hung Huang, T. Chung-Sung, Aerosol Air Qual. Res. 14 (2014) 480-499.

SESSION: AdvancedMaterialsSatAM-R2	5th Intl. Symp. on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development
Sat Oct, 26 2019 / Room: Leda (99/Mezz. F)
Session Chairs: Monika Janowicz; Agnieszka Ciurzyńska; Session Monitor: TBA

11:20: [AdvancedMaterialsSatAM01] Invited
Silver Nanoparticles as Potential Antibacterial Agent: how Silver can overcome Antibiotic Resistance and how Bacteria can Resist Silver
Ales Panacek¹ ; Libor Kvitek² ; Milan Kolar¹ ; Renata Vecerova¹ ; ¹Palacky University, Olomouc, Czech Republic; ²Palacky University in Olomouc, Olomouc, Czech Republic;
Paper Id: 270 [Abstract]

Silver nanoparticles (NPs) exhibit significant antimicrobial activity against a broad range of bacteria and fungi at concentrations ranging from a few ppm to tens of ppm that are not cytotoxic to human cells [1,2]. Silver NPs also strongly enhance antibacterial activity against multiresistant, beta-lactamase and carbapenemase-producing Enterobacteriaceae when combined with antibiotics such as cefotaxime, ceftazidime, meropenem, ciprofloxacin and gentamicin [3]. All the antibiotics, when combined with silver NPs, showed enhanced antibacterial activity at concentrations far below the minimum inhibitory concentrations (tenths to hundredths of one ppm) of individual antibiotics and silver NPs. As a result, silver NPs have already been successfully applied in various biomedical and antimicrobial technologies and products used in every-day life as an alternative to conventional antimicrobials. While bacterial resistance to antibiotics has been discussed extensively in the literature, the possible development of resistance to silver NPs after repeated long-term exposure has not been fully explored. We report that the Gram-negative bacteria can develop resistance to silver NPs after prolonged exposure. The observed resistance stems from the production of the adhesive flagellum protein flagellin, which triggers the aggregation of silver NPs and eliminates their antibacterial effects. The resistance mechanism cannot be overcome by stabilization of silver NPs, by polymers or by surfactants. It is possible, however, to suppress it by inhibiting flagellin production with pomegranate rind extract [4].

References:
[1] Panacek A., Kvitek L., Prucek R. et al., J. Phys. Chem. B 110, 33 (2006) 16248-16253.\n[2] Panacek A., Kolar M., Vecerova R. et al., Biomaterials 30, 31 (2009) 6333-6340.\n[3] Panacek A., Smekalova M., Vecerova R., et al., Colloids Surf., B 142 (2016) 392-399.\n[4] Panacek A., Kvitek L., Smekalova M. et al., Nature Nat. 13, (2018) 65-72.