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Open Access
The effect of water activity and temperature on the growth and lipolytic activity of Penicillium chrysogenum (Thom) and Eurotium herbariorum (Wigg.) strains
(Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2016) Janda, Katarzyna; Markowska-Szczupak, Agata; Ulfig, Krzysztof; Department of Biochemistry and Human Nutrition, Pomeranian Medical University in Szczecin; Institute of Inorganic Technology and Environment Engineering, West Pomeranian University of Technology, Szczecin; School of Public Health, Medical University of Silesia, Bytom
The aim of the study was to determine the effect of water activity (aw) and temperature on the growth and tributyrin hydrolysis of Penicillium chrysogenum and Eurotium herbariorum strains isolated from rape, soya-bean and sunflower seeds. The study demonstrated differences in daily growth rates, tributyrin hydrolysis zones and tributyrin hydrolysis indices in different strains of the same species; depending on the seeds they had been isolated from. E. herbariorum strains, unlike P. chrysogenum strains, did not grow on tributyrin at 15°C and 0.850 aw. No hydrolysis zones of oil substrate were found under these conditions. E. herbariorum and P. chrysogenum showed marked differences in their tributyrin hydrolysis indices. For P. chrysogenum strains somewhat higher values were recorded for cultures at 15°C. However, the highest indices of tributyrin hydrolysis at 15°C and 25°C were recorded at the lowest level of aw 0.850.
Open Access
Influence of distillation apparatus and distillation time on the yield and chemical composition of winter savory essential oil
(Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2017) Wesołowska, Aneta; Grzeszczuk, Monika; Jadczak, Dorota; Department of Organic and Physical Chemistry, West Pomeranian University of Technology, Szczecin; Department of Horticulture, West Pomeranian University of Technology, Szczecin; Department of Horticulture, West Pomeranian University of Technology, Szczecin
The aim of the studies conducted in 2014–2015 was to determine the influence of distillation apparatus as well as distillation time on the yield and chemical composition of winter savory (Satureja montana L.) essential oil. Isolation of the essential oil from S. montana herb, collected during flowering period, was carried out using two different distillation apparatuses: Deryng and Clevenger. Moreover, different distillation times (2, 3 and 4 hours) were also applied. The obtained essential oils were analyzed by gas chromatography-mass spectrometry (GC-MS). GC-MS analysis resulted in the identification of 47 compounds in the essential oils obtained in Deryng and Clevenger apparatus, respectively. Carvacrol (54.44–68.53%) was the major constituent of all S. montana oil samples. Other important compounds were: γ-terpinene (5.21–8.67%), p-cymene (4.40–9.53%), α-terpinene (1.20–2.04%) and β-caryophyllene (4.58–5.77%). On the basis of the obtained data it was proved that the time of distillation of S. montana herb in Deryng apparatus had no significant effect on its content. However, the amount of volatile oil obtained in Clevenger apparatus was significantly influenced by distillation time. Moreover, there was no significant effect of the distillation time on the amount of the main essential oil constituents obtained with both types of apparatuses. However, there was a significant interaction found between the constituent and the distillation time.
Open Access
The effects nano-silver on contamination of spring barley ‘Eunova’ in vitro
(Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2017) Krupa-Małkiewicz, Marcelina; Ochmian, Ireneusz; Mijowska, Kamila; Cendrowski, Krzysztof; Department of Plant Genetics, Breeding and Biotechnology, West Pomerania University of Technology, Szczecin; Department of Horticulture, West Pomerania University of Technology, Szczecin,; Department of Horticulture, West Pomerania University of Technology, Szczecin,; Nanomaterials Physicochemistry Department, West Pomeranian University of Technology, Szczecin
One of the available methods to control in vitro contaminations is nano-silver. Nanosilver is a non-toxic material which shows high capabilities in eliminating microorganisms, e.g., bacteria, viruses or fungus. The aim of the current study was to evaluate the potential of nano- -silver particles on decontamination, growth parameters (plant length, root length) and leaves colour of spring barley ‘Eunova’ in in vitro culture. Plant material consisted of embryos of barley which were placed on MS medium supplemented with 4.0 and 6.0 0 mg ・ dm–3 of nano-silver or submerged in 50 or 100 0 mg ・ dm–3 of nano-silver for 2 or 4 h. The control consisted of embryos treated with 70% alcohol. After 28 days it was observed, that both of the disinfection methods, operating time as well as concentrations of nano-silver, had an influence on a number of contaminations, shoot and root length and colour of the barley leaves. The smallest efficiency (100% contaminations) was found after embryos submerged in 50 mg dm-3 of nano-silver for 2 h. On the other hand, the best disinfection efficiency (0% infection) was obtained when 4.0 0 mg ・ dm–3 nano-silver was added to MS medium. Barley embryos soaked in 100 mg ・ dm–3 in nano-silver solution and grown on MS media with addition of nano-silver independent of their concentration showed similar disinfection effectiveness.
Open Access
Synthesis and Selected Properties of Ester Elastomer Containing Sorbitol
(MDPI, 2020-02-29) Piątek-Hnat, Marta; Bomba, Kuba; Pęksiński, Jakub; West Pomeranian University of Technology in Szczecin. Faculty of Chemical Technology and Engineering; West Pomeranian University of Technology in Szczecin. Faculty of Chemical Technology and Engineering; West Pomeranian University of Technology in Szczecin. Faculty of Electrical Engineering
The aim of this work was synthesizing ester elastomers, using sorbitol as a monomer obtainable from renewable sources. Three polymers were synthesized, utilizing three di erent polycondensation times. Their mechanical and thermal properties were examined and compared. Poly(sorbitol sebacate-co-butylene sebacate) elastomers were synthesized as a result of polycondensation reaction, using sebacic acid, butylene glycol and sorbitol as monomers. Resulting materials had good mechanical properties and a cross-linked structure. Such elastomers are susceptible to hydrolytic degradation which has been confirmed in earlier studies. This paper shows that the material synthesized utilizing a 3.5 h polycondensation time has the most desirable mechanical and thermal properties, and the reaction is characterized by the highest degree of conversion of substrates.
Open Access
The influence of of cross-linking process on the physicochemical properties of new copolyesters containing xylitol
(Elsevier, 2020-03-01) Piątek-Hnat, Marta; Bomba, Kuba; West Pomeranian University of Technology, Faculty of Chemical Technology and Engineering, Department of Polymer and Biomaterials Science; West Pomeranian University of Technology, Faculty of Chemical Technology and Engineering, Department of Polymer and Biomaterials Science
The goal of this research was developing biodegradable and biocompatibile xylitol-based copolymers with im proved mechanical properties, and investigating the change in their thermal and chemical properties with progress of the cross-linking process. Using a raw material of natural origin such as xylitol, a prepolymer was obtained by esterification and polycondensation. Then, at subsequent stages of the crosslinking process in a vacuum dryer, samples of materials were taken to determine the progress of the process using Fourier transform infrared spectroscopy. The method of differential scanning calorimetry also defined changes in the ranges of phase changes occurring at each stage of the crosslinking process. After the crosslinking process, ester materials based on sebacic and succinic acid were characterized in terms of mechanical and surface properties.
Open Access
Structure and Properties of Biodegradable Poly (Xylitol Sebacate-Co-Butylene Sebacate) Copolyester
(MDPI, 2020-03-28) Piątek-Hnat, Marta; Bomba, Kuba; Pęksiński, Jakub; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin
In this work, a bio-based copolyester with good mechanical properties was synthesized and characterized in terms of structure, main properties and biodegradability Determining the chemical structure of such materials is important to understand their behavior and properties. Performing an extraction of insoluble cross-linked polymer using di erent solvents allowed us to analyze how the polymer behaves when subjected to di erent chemical environments, and to obtain soluble samples suitable for more in-depth analysis. Chemical structure of poly (xylitol sebacate-co-butylene sebacate) was determined by a 1H NMR and FTIR analysis of both prepolymer gel sample and samples obtained by extraction of cross-linked polymer using di erent solvents. Block structure of the copolymer was confirmed by both NMR and DSC. Gel fraction, swelling value, water contact angle, and mechanical properties were also analyzed. Biodegradability of this material was confirmed by performing enzymatic and hydrolytic degradation. Synthesizing sugar-alcohol based copolyester using three monomers leads to obtaining a material with interesting chemical structure and desirable mechanical properties comparable to conventional elastomers.
Open Access
Effect of E-Beam Irradiation on Thermal and Mechanical Properties of Ester Elastomers Containing Multifunctional Alcohols
(MDPI, 2020-05-02) Piątek-Hnat, Marta; Bomba, Kuba; Pęksiński, Jakub; Kozłowska Agnieszka; Sośnicki, Jacek G.; Idzik, Tomasz J.; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin
The aim of this work was to investigate the thermal and mechanical properties of novel, electron beam-modified ester elastomers containing multifunctional alcohols. Polymers tested in this work consist of two blocks: sebacic acid–butylene glycol block and sebacic acid–sugar alcohol block. Di erent sugar alcohols were utilized in the polymer synthesis: glycerol, sorbitol, xylitol, erythritol, and mannitol. The polymers have undergone an irradiation procedure. The materials were irradiated with doses of 50 kGy, 100 kGy, and 150 kGy. The expected e ect of using ionizing radiation was crosslinking process and improvement of the mechanical properties. Additionally, a beneficial side e ect of the irradiation process is sterilization of the a ected materials. It is also worth noting that the materials described in this paper do not require either sensitizers or cross-linking agent in order to perform radiation modification. Radiation-modified poly(polyol sebacate-co-butylene sebacate) elastomers have been characterized in respect to the mechanical properties (quasi-static tensile tests), cross-link density, thermal properties (Di erential Scanning Calorimetry (DSC)), chemical properties: Fourier transform infrared spectroscopy (FTIR), and wettability (water contact angle). Poly(polyol sebacate-co-butylene sebacate) preopolymers were characterized with nuclear magnetic resonance spectroscopy (1HNMRand 13C NMR) and gel permeation chromatography (GPC). Thermal stability of cross-linked materials (directly after synthesis process) was tested with thermogravimetric analysis (TGA).
Open Access
Tailoring the Physico-chemical Properties of Poly(xylitol-dicarboxylate-co-butylene dicarboxylate) Polyesters by Adjusting the Cross-Linking Time
(MDPI, 2020-07-03) Piątek-Hnat, Marta; Sładkiewicz, Paulina; Bomba, Kuba; Pęksiński, Jakub; Kozłowska, Agnieszka; Sośnicki, Jacek G.; Idzik, Tomasz J.; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin
Determining the cross-linking time resulting in the best achievable properties in elastomers is a very important factor when considering their mass production. In this paper, five biodegradable polymers were synthesized—poly(xylitol-dicarboxylate-co-butylene dicarboxylate) polymers, based on xylitol obtained from renewable sources. Five di erent dicarboxylic acids with even numbers of carbon atoms in the aliphatic chain were used: succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid. Samples were taken directly after polycondensation (prepolymer samples) and at di erent stages of the cross-linking process. Physiochemical properties were determined by a gel fraction test, di erential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), quasi-static tensile tests, nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), and an in vitro biodegradation test. The best cross-linking time was determined to be 288h. Properties and degradation time can be tailored for specific applications by adjusting the dicarboxylic acid chain length.
Open Access
Influence of e-beam irradiation on the physicochemical properties of poly(polyol succinate-co-butylene succinate) ester elastomers
(2020-07-17) Piątek-Hnat, Marta; Bomba, Kuba; Pęksiński, Jakub; Kozłowska, Agnieszka; Sośnicki, Jacek G.; Idzik, Tomasz J.; Piwowarska, Danuta; Janik, Jolanta; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin
The purpose of this research was synthesis and electron beam modification of novel ester elastomers consisting of sugar alcohol–succinic acid block and butylene glycol–succinic acid block. Four di erent alditols were used in the synthesis—sorbitol, erythritol, xylitol, and glycerol. The materials were irradiated with doses of 50, 100, and 150 kGy in order to determine which dose is the most beneficial. As expected, irradiation of the materials has led to the cross-link density becoming higher and improvement of the mechanical properties. Additionally, the materials were also sterilized in the process. The great advantage of elastomers described in the paper is the fact that they do not need chemical cross-linking agents or sensitizers in order to undergo radiation modification. The following tests were performed on cross-linked poly(polyol succinate-co-butylene succinate) elastomers: quasi-static tensile test, determination of cross-link density, di erential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMTA), wettability (water contact angle), and Fourier transform infrared spectroscopy (FTIR). In order to confirm successful synthesis, prepolymers were analyzed by nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR).
Embargo
Effect of microwave assisted solvothermal process parameters on carbon dioxide adsorption properties of microporous carbon materials
(Elsevier, 2020-08-02) Staciwa, Piotr; Sibera, Daniel; Pełech, Iwona; Narkiewicz, Urszula; Lojkowski, Witold; Dąbrowska, Sylwia; Cormia, Robert; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Instytut Wysokich Ciśnień Polskiej Akademii Nauk; Institute of High Pressure Physics, Polish Academy of Science; Politechnika Warszawska. Wydział Inżynierii Materiałowej; Faculty of Materials Science and Engineering, Warsaw University of Technology; Chemistry Faculty, Chemistry Department, Foothill College
In this work, production and characterization of carbon spheres from resorcinol and formaldehyde, using a microwave assisted solvothermal reactor, is presented. The influence of different experimental conditions, e.g., reaction time, pressure, and power, on the structure of the obtained materials, and carbon dioxide adsorption properties, was studied. Using the method described in this work, it is possible to significantly reduce the reaction time, to as low as 10 min, compared with widely described processes carried out in autoclaves, requiring several hours. Simultaneously, it was discovered that the application of higher reactor pressures, over 3 MPa, resulted in the destruction of spherical shape and the formation of graphitic layers. The importance of micropores below 0.4 nm, for adsorption of carbon dioxide, was also shown in this work. Microporous carbon spheres with efficient CO2 adsorption properties (nearly 7 mmol/g at 1 bar and 0 ◦C) were synthesized using this process.
Open Access
Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption
(MDPI, 2020-10-13) Pełech, Iwona; Sibera, Daniel; Staciwa, Piotr; Narkiewicz, Urszula; Cormia, Robert; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej; Department of Chemical and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Chemistry Faculty, Chemistry Department, Foothill College
In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the e ect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly di erent from those obtained at higher pressures. In addition, CO2 uptake was not a ected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more e ect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 C, but had no e ect on it at 0 C.
Open Access
Magnetic moment centers in titanium dioxide photocatalysts loaded on reduced graphene oxide flakes
(De Gruyter, 2021-01) Guskos, Nikos; Zolnierkiewicz, Grzegorz; Guskos, Aleksander; Aidinis, Konstantinos; Wanag, Agnieszka; Kusiak-Nejman, Ewelina; Narkiewicz, Urszula; Morawski, Antoni W.; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie
A whole series of titania nanocomposites modified with reduced graphene oxide (rGO) was prepared using solvothermal method followed by calcination. Modification of titania with rGO has been found to lead to better photocatalytic properties. The highest photocatalytic performance was obtained at calcination temperature of 600 degrees C. Electron paramagnetic resonance/ferromagnetic resonance measurements showed oxygen defects and ferromagnetic ordering systems. The linewidth of resonance line of oxygen defects decreased linearly with calcination temperature increasing up to 600 degrees C and an accompanying growth of mean crystallite size of anatase phase. The integrated resonance line intensity of oxygen defects depended on the calcination temperature and caused a very large increase in the intensity of resonance lines originating from oxygen defects, because inert atmosphere of calcination was enhanced by graphene presence. The occurrence of magnetic ordering system significantly influenced the performance of photocatalytic processes by changing the amount of oxygen defects.
Open Access
Physical Effects of Radiation Modification of Biodegradable Xylitol-Based Materials Synthesized Using a Combination of Different Monomers
(MDPI, 2021-03-26) Piątek-Hnat, Marta; Bomba, Kuba; Kowalski-Stankiewicz, Janusz P.; Pęksiński, Jakub; Kozłowska, Agnieszka; Sośnicki, Jacek G.; Idzik, Tomasz J.; Schmidt, Beata; Kowalczyk, Krzysztof; Walo, Marta; Kochmańska, Agnieszka; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; Pomeranian Medical University in Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; Institute of Nuclear Chemistry and Technology,Warszawa; West Pomeranian University of Technology, Szczecin
There is a possibility of obtaining xylitol-based elastomers sharing common characteristics of biodegradability, thermal stability, and elastomeric behavior by using monomers with different chain-lengths. Therefore, we have synthesized eight elastomers using a combination of four different diols (ethanediol, 1.3-propanediol, 1.4-buanediol, and 1.5-pentanediol) and two different dicarboxylic acids (succinic acid and adipic acid). The obtained materials were further modified by performing e-beam treatment with a dose of 100 kGy. Materials both before and after radiation modification were tested by DSC, DMTA, TGA, tensile tests, gel fraction determination, hydrolytic and enzymatic degradation tests, 1H NMR and 13C NMR and FTIR.
Open Access
E-Beam Effects on Poly(Xylitol Dicarboxylate-co-diol Dicarboxylate) Elastomers Tailored by Adjusting Monomer Chain Length
(MDPI, 2021-04-02) Piątek-Hnat, Marta; Bomba, Kuba; Kowalski-Stankiewicz, Janusz P.; Pęksiński, Jakub; Kozłowska, Agnieszka; Sośnicki, Jacek G.; Idzik, Tomasz J.; Schmidt, Beata; Kowalczyk, Krzysztof; Walo, Marta; Mikołajczak, Grzegorz; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; Pomeranian Medical University in Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin; Institute of Nuclear Chemistry and Technology,Warszawa; West Pomeranian University of Technology, Szczecin; West Pomeranian University of Technology, Szczecin
Poly(xylitol dicarboxylate-co-diol dicarboxylate) elastomers can by synthesized using wide variety of monomers with different chain lengths. Obtained materials are all biodegradable, thermally stable elastomers, but their specific properties like glass transition temperature, degradation susceptibility, and mechanical moduli can be tailored for a specific application. Therefore, we synthesized eight elastomers using a combination of two dicarboxylic acids, namely suberic and sebacic acid, and four different diols, namely ethanediol, 1,3-propanediol, 1,4-buanediol, and 1,5- pentanediol. Materials were further modified by e-beam treatment with a dose of 100 kGy. Materials both before and after radiation modification were tested using tensile tests, gel fraction determination, 1H NMR, and 13C NMR. Thermal properties were tested by Differential Scanning Calorimetry (DSC), Dynamic Thermomechanical Analysis (DMTA) and Thermogravimetric Analysis (TGA). Degradation susceptibility to both enzymatic and hydrolytic degradation was also determined.
Open Access
Influence of the calcination of TiO2-reduced graphite hybrid for the photocatalytic reduction of carbon dioxide
(Elsevier, 2021-06-09) Morawski, Antoni Waldemar; Kusiak-Nejman, Ewelina; Wanag, Agnieszka; Narkiewicz, Urszula; Edelmannova, Miroslava; Reli, Martin; Koci, Kamila; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej. Katedra Technologii Chemicznej Nieorganicznej i Inżynierii Środowiska; Technical University of Ostrava. Institute of Environmental Technology; West Pomeranian University of Technology in Szczecin. Faculty of Chemical Technology and Engineering. Department of Inorganic Chemical Technology and Environment Engineering
In this work, a conversion of carbon dioxide (CO2) into methane, carbon monoxide, as well as hydrogen was investigated. The TiO2/rGO photocatalysts were prepared by two steps: solvothermal method and calcination at 500, 800, and 1000 ◦C in an argon atmosphere. The obtained samples were characterized by X-ray diffraction (XRD), UV–vis diffuse reflection spectroscopy (UV–vis/DRS), N2 adsorption-desorption and analysis of carbon content. The activity of photocatalysts was evaluated in the photocatalytic reduction of CO2. The TiO2/rGO-10 without calcination showed the highest activity toward CO2 conversion. It was found that all samples after rGO modification exhibited good activity toward H2 generation with high selectivity. The enhanced photocatalytic performance was attributed mainly to the presence of graphene due to its excellent electron transport/collection ability.
Open Access
DC magnetization of titania supported on reduced graphene oxide flakes
(De Gruyter, 2021-10-19) Guskos, Nikos; Żołnierkiewicz, Grzegorz; Guskos, Aleksander; Aidinis, Konstantinos; Glenis, Spiros; Wanag, Agnieszka; Kusiak-Nejman, Ewelina; Narkiewicz, Urszula; Morawski, Antoni W.; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie
DC magnetization of a series of titania nano-composites modified with reduced graphene oxide (rGO) has been investigated. Hysteresis loops observed at room temperature disappeared at low temperatures. At a temperature of about 100 K, a phase transition to the super-ferromagnetic order state was observed, probably due to the linear expansion and self-reorientation of the magnetic moments. Processes associated with magnetic moment reorientation can cause a hysteresis loop to disappear at low temperatures as well as superferromagnetic ordering. It was suggested that the isolated nanoparticle in the nanopore could be used to create a "compass" at a nanometer-sized level that would be many times more sensitive than the conventional one. Measurements of the zero-field cooling and field cooling modes do not exclude the possibility of the coexistence of a superparamagnetic state.
Open Access
ZnO/Carbon Spheres with Excellent Regenerability for Post-Combustion CO2 Capture
(MDPI, 2021-10-28) Pełech, Iwona; Sibera, Daniel; Staciwa, Piotr; Kusiak-Nejman, Ewelina; Kapica-Kozar, Joanna; Wanag, Agnieszka; Narkiewicz, Urszula; Morawski, Antoni W.; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Technologii i Inżynierii Chemicznej. Katedra Technologii Chemicznej Nieorganicznej i Inżynierii Środowiska; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydział Budownictwa i Inżynierii Środowiska. Katedra Budownictwa Ogólnego; West Pomeranian University of Technology in Szczecin. Faculty of Chemical Technology and Engineering. Department of Inorganic Chemical Technology and Environment Engineering; West Pomeranian University of Technology in Szczecin. Faculty of Civil and Environmental Engineering. Department of General Civil Engineering
This paper examines the synthesis of the ZnO/carbon spheres composites using resorcinol—formaldehyde resin as a carbon source and zinc nitrate as a zinc oxide source in a solvothermal reactor heated with microwaves. The influence of activation with potassium oxalate and modification with zinc nitrate on the physicochemical properties of the obtained materials and CO2 adsorption capacity was investigated. It was found that in the case of nonactivated material as well as activated materials, the presence of zinc oxide in the carbon matrix had no effect or slightly increased the values of CO2 adsorption capacity. Only for the material where the weight ratio of carbon:zinc was 2:1, the decrease of CO2 adsorption capacity was reported. Additionally, CO2 adsorption experiments on nonactivated carbon spheres and those activated with potassium oxalate with different amounts of zinc nitrate were carried out at 40 °C using thermobalance. The highest CO2 adsorption capacity at temperature 40 °C (2.08 mmol/g adsorbent) was achieved for the material after activation with potassium oxalate with the highest zinc nitrate content as ZnO precursor. Moreover, repeated adsorption/desorption cycle experiments revealed that the as-prepared carbon spheres were very good CO2 adsorbents, exhibiting excellent cyclic stability with a performance decay of less than 10% over up to 25 adsorption-desorption cycles.
Open Access
CO2 Reduction to Valuable Chemicals on TiO2-Carbon Photocatalysts Deposited on Silica Cloth
(MDPI, 2021-12-28) Morawski, Antoni Waldemar; Ćmielewska, Katarzyna; Witkowski, Kordian; Kusiak-Nejman, Ewelina; Pełech, Iwona; Staciwa, Piotr; Ekiert, Ewa; Sibera, Daniel; Wanag, Agnieszka; Gano, Marcin; Narkiewicz, Urszula
A new photocatalyst for CO2 reduction has been presented. The photocatalyst was prepared from a combination of a commercial P25 with a mesopore structure and carbon spheres with a microporous structure with high CO2 adsorption capacity. Then, the obtained hybrid TiO2-carbon sphere photocatalysts were deposited on a glass fiber fabric. The combined TiO2-carbon spheres/silica cloth photocatalysts showed higher efficiency in the two-electron CO2 reduction towards CO than in the eight-electron reaction to methane. The 0.5 g graphitic carbon spheres combined with 1 g of TiO2 P25 resulted in almost 100% selectivity to CO. From a practical point of view, this is promising as it economically eliminates the need to separate CO from the gas mixture after the reaction, which also contains CH4 and H2.
Open Access
CO2 Reduction to Valuable Chemicals on TiO2-Carbon Photocatalysts Deposited on Silica Cloth
(MDPI, 2021-12-28) Morawski, Antoni W.; Cmielewska, Katarzyna; Witkowski, Kordian; Kusiak-Nejman, Ewelina; Pelech, Iwona; Staciwa, Piotr; Ekiert, Ewa; Sibera, Daniel; Wanag, Agnieszka; Gano, Marcin; Narkiewicz, Urszula; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie
A new photocatalyst for CO2 reduction has been presented. The photocatalyst was prepared from a combination of a commercial P25 with a mesopore structure and carbon spheres with a microporous structure with high CO2 adsorption capacity. Then, the obtained hybrid TiO2-carbon sphere photocatalysts were deposited on a glass fiber fabric. The combined TiO2-carbon spheres/silica cloth photocatalysts showed higher efficiency in the two-electron CO2 reduction towards CO than in the eight-electron reaction to methane. The 0.5 g graphitic carbon spheres combined with 1 g of TiO2 P25 resulted in almost 100% selectivity to CO. From a practical point of view, this is promising as it economically eliminates the need to separate CO from the gas mixture after the reaction, which also contains CH4 and H-2.
Open Access
The Effect of the Modification of Carbon Spheres with ZnCl2 on the Adsorption Properties towards CO2
(MDPI, 2022-02) Pełech, Iwona; Staciwa, Piotr; Sibera, Daniel; Kusiak-Nejman, Ewelina; Morawski, Antoni W.; Kapica-Kozar, Joanna; Narkiewicz, Urszula; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Department of General Civil Engineering, Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin; Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin
Zinc chloride and potassium oxalate are often applied as activating agents for carbon materials. In this work, we present the preparation of ZnO/carbon spheres composites using resorcinol-formaldehyde resin as a carbon source in a solvothermal reactor heated with microwaves. Zinc chloride as a zinc oxide source and potassium oxalate as an activating agent were applied. The effect of their addition and preparation conditions on the adsorption properties towards carbon dioxide at 0 degrees C and 25 degrees C were investigated. Additionally, for all tested sorbents, the CO2 sorption tests at 40 degrees C, carried out utilizing a thermobalance, confirmed the trend of sorption capacity measured at 0 and 25 degrees C. Furthermore, the sample activated using potassium oxalate and modified using zinc chloride (a carbon-to-zinc ratio equal to 10:1) displayed not only a high CO2 adsorption capacity (2.69 mmol CO2/g at 40 degrees C) but also exhibited a stable performance during the consecutive multicycle adsorption-desorption process.

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