Publikační činnost Katedry chemie a fyzikálně-chemických procesů / Publications of Department of Chemistry and Physico-Chemical Processes (651)

Permanent URI for this collectionhttp://hdl.handle.net/10084/146157

Kolekce obsahuje bibliografické záznamy publikační činnosti akademických pracovníků Katedry chemie a fyzikálně-chemických procesů (651) v časopisech registrovaných ve Web of Science od roku 2022.
Do kolekce jsou zařazeny:
a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská-Technická univerzita Ostrava (VŠB-TUO),
b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

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Now showing 1 - 20 out of 57 results

Ex situ Raman mapping of LiMn2O4 electrodes cycled in lithium-ion batteries
(American Chemical Society, 2024) Buchberger, Dominika A.; Hamankiewicz, Bartosz; Michalska, Monika; Głaszczka, Alicja; Czerwiński, Andrzej
In this study, we focus on the large-scale ex situ Raman mapping of LiMn2O4 (LMO) electrodes maintained at varying states of charge. A comprehensive statistical analysis has been conducted at an area of ca. 3660 mu m(2) on more than 3100 collected spectra for each LMO electrode sample. High-definition ex situ Raman maps provide profound insight into the lithiation process, offering an additional perspective on the mechanism of LMO intercalation. These maps clearly depict the coexistence of two phases, with evident phase transitions and state-of-charge gradients. The set of spectra with various state-of-charge has been successfully deconvoluted taking into account the two-phase character of the ongoing reaction. In addition, we performed the study on the samples operated for 50 cycles at the high C-rates and tracked their delithiation state and impurity formation. This technique serves as a complementary visualization and analytical tool alongside other bulk-type methods employed in battery diagnostics. Importantly, this ex situ Raman mapping approach is applicable to any electrode material exhibiting a Raman response.
Removing 65 years of approximation in rotating ring disk electrode theory with physics-informed neural networks
(American Chemical Society, 2024) Chen, Haotian; Smetana, Bedřich; Novák, Vlastimil; Zhang, Yuanmin; Sokolov, Stanislav V.; Kätelhön, Enno; Luo, Zhiyao; Zhu, Mingcheng; Compton, Richard G.
The rotating Ring Disk Electrode (RRDE), since its introduction in 1959 by Frumkin and Nekrasov, has become indispensable with diverse applications in electrochemistry, catalysis, and material science. The collection efficiency (N) is an important parameter extracted from the ring and disk currents of the RRDE, providing valuable information about reaction mechanism, kinetics, and pathways. The theoretical prediction of N is a challenging task: requiring solution of the complete convective diffusion mass transport equation with complex velocity profiles. Previous efforts, including by Albery and Bruckenstein who developed the most widely used analytical equations, heavily relied on approximations by removing radial diffusion and using approximate velocity profiles. 65 years after the introduction of RRDE, we employ a physics-informed neural network to solve the complete convective diffusion mass transport equation, to reveal the formerly neglected edge effects and velocity corrections on N, and to provide a guideline where conventional approximation is applicable.
Comparative study of photocatalysis with bulk and nanosheet graphitic carbon nitrides enhanced with silver
(Springer Nature, 2024) Michalska, Monika; Pavlovský, Jiří; Simha Martynková, Gražyna; Kratošová, Gabriela; Hornok, Viktória; Nagy, Peter B.; Novák, Vlastimil; Szabó, Tamás
The main goal of this research is to investigate the effectiveness of graphitic carbon nitride (g-C3N4, g-CN) in both bulk and nanosheet forms, which have been surface-modified with silver nanoparticles (Ag NPs), as photocatalysts for the degradation of acid orange 7 (AO7), a model dye. The photodegradation of AO7 dye molecules in water was used to test the potential photocatalytic properties of these powder materials under two different lamps with wavelengths of 368 nm (UV light) and 420 nm (VIS light). To produce Ag NPs (Ag content 0.5, 1.5, and 3 wt%) on the g-CN materials, a new synthesis route based on a wet and low-temperature method was proposed, eliminating the need for reducing agents. The photodegradation activity of the samples increased with increasing silver content, with the best photocatalytic performances achieved for bulk g-CN samples and nanosheet silver-modified samples (with the highest content of 3 wt% Ag) under UV light, i.e., more than 75% and 78%, respectively. The VIS-induced photocatalytic activity of both examined series was higher than that of UV. The highest activities of 92% and 98% were achieved for the 1.5% Ag-modified g-CN bulk and nanosheet materials. This research presents an innovative, affordable, and environmentally friendly chemical approach to synthesizing photocatalysts that can be used for degrading organic pollutants in wastewater treatment.
Enhanced electrochemical properties of multiwalled carbon nanotubes modified with silver nanoparticles for energy storage application
(Elsevier, 2024) Jain, Amrita; Michalska, Monika
This work reports an easy, straightforward, and cost-effective method to synthesize a composite material using multiwalled carbon nanotubes (MWCNTs) and silver nanoparticles (Ag NPs) for application as an electrode in supercapacitors. The objective of this work was to enhance the charge transfer mechanism in supercapacitor cells by introducing the conductive particles in the MWCNT framework. The pivotal studies, like scanning (SEM), and transmission (TEM) electron microscopy, X-ray diffraction (XRD), Raman, and X-ray photoelectron (XPS) spectroscopy confirmed the formation of the composite as well as a successful deposition of Ag NPs on MWCNT. The surface area of the composite was evaluated by using the N2 adsorption-desorption studies and it was found to be of the order of 358 m2 g-1. Electrochemical studies were performed using a two-electrode system. Magnesium ion-based polymer gel electrolyte was used as an electrolyte material. The single electrode-specific capacitance was observed to be -31.9 F g-1 with power density and energy density values of -4.4 kW kg-1 and 1.2 Wh kg-1, respectively, at a current density of 0.46 A g-1. The cell was stable up to -5000 charge-discharge cycles with -96% of capacitance retention at the end of 5000 cycles.
Photoreforming for microplastics recycling: A critical review
(Elsevier, 2024) Praus, Petr
Microplastics in the environment are a serious global problem for our society and there is a strong need to develop technologies for their removal and recycling. Photoreforming based on photocatalysis is a novel approach to convert microplastics to useful chemical compounds. In this work, the literature related to the photoreforming of microplastics was reviewed. The main product of the photoreforming was hydrogen obtained from polyethylene terephthalate (PET) and polylactic acid (PLA) with the highest yields of 113 mmol g- 1 h-1 and 95.6 mmol g- 1 h-1, respectively. The hydrogen yields were processed by the non-parametric Mann-Whitney, Kolmogorov-Smirnov, Moods median, and Kruskal-Wallis tests. The pre-treatment of microplastics before the photoreforming was not found to be a critical factor for the photoreforming. In addition, the photoreforming of PET and PLA was statistically proved to provide similar hydrogen yields. The selection of suitable photocatalysts was identified as the most important factor in the photoreforming process due to the effective separation of photoinduced electrons and holes. The reaction conditions should be optimized, especially in terms of the concentration of photocatalysts in the reaction suspensions of highly concentrated KOH or NaOH. The advantages of the photoreforming, such as reactions at ambient temperature and pressure, and the use of visible (solar) irradiation, are a challenge for further research mainly concerning the hydrogen production. More experimental data are necessary to evaluate and optimize some key parameters of this photoreforming process.
Influence of Cu incorporation on activated carbon for CO2 adsorption and electrocatalytic hydrogen evolution reaction
(Elsevier, 2024) Chang, Lee-Lee; Hu, Chechia; Huang, Chun-Chieh; Matějka, Vlastimil; Tung, Kuo-Lun
Electrocatalytic hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) have emerged as promising approaches toward a sustainable and green society. In this study, potassium citrate-derived activated carbon (ACK) was synthesized and incorporated with copper (Cu) for electrocatalytic reduction under CO2 and N2 flows. The ACK sample exhibited high CO2 adsorption properties to generate different carbonate species and served as an electrocatalyst after Cu incorporation. To understand the competitive reactions of HER and CO2RR, different reaction conditions were applied. Under a CO2 flow, the Cu-ACK sample revealed a high and long-term current density of single bond0.9 V, and H2 (2.642 mmol) was determined as the major product, and CH3COOH, and C2H5OH as minor products. A reaction mechanism was proposed to elucidate the reaction path for the electrocatalytic CO2RR and HER.
Quality of zinc coating formed on structural steel by hot-dip galvanizing after surface contamination
(MDPI, 2024) Vontorová, Jiřina; Mohyla, Petr; Kreislová, Kateřina
This paper deals with the evaluation of the surface of structural steel whose samples were deliberately contaminated with transparent spray primer, adhesive label glue, and welding sprays prior to hot-dip galvanizing. The galvanized samples were studied by optical microscopy, GDOES, adhesion tests, and condensation humidity tests. The effect of surface contamination on the quality of the zinc coating was found to be significant. In some cases, the zinc coating is damaged (after contamination with welding sprays), in others, it is completely absent (after contamination with spray primer or adhesive label glue).
Metal-free hybrid nanocomposites of graphitic carbon nitride and char: Synthesis, characterisation and photocatalysis under visible irradiation
(Elsevier, 2024) Smýkalová, Aneta; Kinnertová, Eva; Slovák, Václav; Praus, Petr
Background The hybrid nanocomposites of graphitic carbon nitride (g-C3N4) and char were synthesised from melamine and hydroxyethyl cellulose/glucose to obtain metal-free photocatalysts active under visible irradiation. The nanocomposites were tested for the degradation of phenol and ofloxacin. Methods The nanocomposites were characterized by elemental and thermal analysis. Their electronic properties were studied by UV–Vis and photoluminescence spectroscopy. Texture and morphology were studied by physisorption of nitrogen, X-ray diffraction, infrared spectroscopy, X-ray photoelectron spectroscopy, and by transmission electron microscopy. The photocatalytic experiments were performed under the LED irradiation of 420 nm. Significant findings Hydroxyethyl cellulose and glucose formed char which was incorporated in the g-C3N4 structure. The char acted as an electron collector enabling the separation of photoinduced electrons and holes. In this way, the photocatalytic activity of g-C3N4 increased and 96% of ofloxacin was degraded during after 120 min. In addition, in this work the total combustion of graphitic carbon nitride up to 800 oC was investigated for the first time.
Carbon framework modification; an interesting strategy to improve the energy storage and dye adsorption
(Royal Society of Chemistry, 2024) Michalska, Monika; Pietrzyk-Thel, Paulina; Sobczak, Kamil; Janssen, Mathijs; Jain, Amrita
Porous carbons find various applications, including as adsorbents for clean water production and as electrode materials in energy storage devices such as supercapacitors. While supercapacitors reach higher power densities than batteries, they are less widely used, as their energy density is lower. We present a low-temperature wet ultrasonochemical synthesis technique to modify the surface of activated carbon with 1 wt% Cu nanoparticles. We analyzed the modified carbon using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy and confirmed the composite formation by N2 adsorption–desorption isotherms at 77 K. For comparison, we did the same tests on pristine carbon. We used the modified carbon as an electrode material in a home built supercapacitor filled with gel polymer electrolyte and as an absorbent of Malachite green dye. In both applications, the modified carbon performed substantially better than its pristine counterpart. The modified-carbon supercapacitor exhibited a single electrode-specific capacitance of approximately 68.9 F g 1. It also demonstrated an energy density of 9.8 W h kg 1 and a power density of 1.4 kW kg 1. These values represent improvements over the pristine-carbon supercapacitor, with increases of 25.7 F g 1 in capacitance, 3.8 W h kg 1 in energy density, and 0.5 kW kg 1 in power density. After 10000 charging–discharging cycles, the capacitance of the modified-carbon supercapacitor decreased by approximately 10%, indicating good durability of the material. We found that the modified carbon’s absorbance capacity for Malachite dye is more than that of the pristine carbon; the adsorption capacity value was B153.16 mg g 1 for modified carbon with pseudo-second kinetic order, in accordance with the Redlich–Peterson adsorption model.
Exploring the potential of microbial biomass and microbial extracted oils in tribology: a sustainable frontier for environmentally acceptable lubricants
(Taylor & Francis, 2024) Bernat, Szymon; Di Bartolomeo, Francesca; Armada, Sergio; Valaker, Emil; Bonturi, Nemailla; Koseto, Deni; Haugen, Tone; Kvernbråten, Ann-Karin; Stavárek, Petr; Večeř, Marek; Zelenka, Ladislav
Mineral oil-derived lubricants, extracted from fossil fuels, account for approximately 90% of the lubricant market. A large proportion of these lubricants end up in the environment through usage, spillage, and disposal, leading to contamination of aquatic systems, ecosystems, and agricultural lands. To address this, new regulations were released (e.g. Vessel General Permit 2013) to promote the use of Environmentally Acceptable Lubricants (EALs) over conventional, toxic, non-biodegradable mineral oils. Today, the range of EAL is limited, particularly affecting the maritime sector. Since 2013, the variety and effectiveness of EALs have improved, but further advancements and cost reductions are essential. This study focuses on developing sustainable bio-based additives from microbial processes to enhance EALs. These additives, sourced through fermentation, avoid using fossil fuels and do not require arable land, preserving water resources and food production areas. The research reveals that yeast, high in sulfur and phosphorus, and microbial oils, mainly carboxylic acids, effectively stabilize EAL formulations, reducing friction and wear in water-based lubricants. Microbial oils are superior in reducing friction, while yeast offers better wear protection. This study opens the possibility of incorporating various bio-based products into EALs, providing a sustainable, environmentally friendly option.
Pyrolysis of natural rubber-cellulose composites: isoconversional kinetic analysis based on thermogravimetric data
(Springer Nature, 2024) Dobrovská, Jana; Skalková, Petra; Drozdová, Ľubomíra; Labaj, Ivan; Zlá, Simona; Dubec, Andrej; Kawuloková, Monika
Despite the current growing interest in rubber composites with natural organic fillers, there is a lack of kinetic analyses that describe the decomposition of these materials during pyrolysis. For this reason, the main objective of this study was the kinetic analysis and determination of formal kinetic parameters for the pyrolytic decomposition of NR-CEL composites with different cellulose content (0, 30, 45, and 55 phr). Thermogravimetric measurements were made at heating rates of 2, 4, 6, 8, 10, and 20 degrees C min-1 in the temperature range of 20-600 degrees C. First, Friedman and KAS model-free methods were applied. Therefore, model-based methods and the model-fitting procedure were used to find the optimal multi-step kinetic model. The proposed final model consists of two parallel processes, which are kinetically independent: A -> B -> C and D -> E -> F. For each step, a kinetic triplet was calculated: the apparent activation energy, the pre-exponential factor, and the kinetic parameters of the extended empirical Prout-Tompkins model. The master plots method was used to determine the kinetic decomposition mechanism of the individual steps. It was found that step A -> B has the shape of an nth-order model, step B -> C mainly follows the diffusion model, the mechanism of step D -> E transfers from a random scission kinetics model to an nth-order model with an increasing amount of CEL, and step E -> F obeys the chain scission mechanism.
Discovering electrochemistry with an electrochemistry-informed neural network (ECINN)
(Wiley, 2024) Chen, Haotian; Yang, Minjun; Smetana, Bedřich; Novák, Vlastimil; Matějka, Vlastimil; Compton, Richard G.
Machine learning is increasingly integrated into chemistry research by guiding experimental procedures, correlating structure and function, interpreting large experimental datasets, to distill scientific insights that might be challenging with traditional methods. Such applications, however, largely focus on gaining insights via big data and/or big computation, while neglecting the valuable chemical prior knowledge dwelling in chemists' minds. In this paper, we introduce an Electrochemistry-Informed Neural Network (ECINN) by explicitly embedding electrochemistry priors including the Butler-Volmer (BV), Nernst and diffusion equations on the backbone of neural networks for multi-task discovery of electrochemistry parameters. We applied the ECINN to voltammetry experiments of Fe2+/Fe3+ ${{\rm F}{{\rm e}}<^>{2+}/{\rm F}{{\rm e}}<^>{3+}}$ and RuNH362+/RuNH363+ ${{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}<^>{2+{\rm \ }}/{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}<^>{3+{\rm \ }}}$ redox couples to discover electrode kinetics and mass transport parameters. Notably, ECINN seamlessly integrated mass transport with BV to analyze the entire voltammogram to infer transfer coefficients directly, so offering a new approach to Tafel analysis by outdating various mass transport correction methods. In addition, ECINN can help discover the nature of electron transfer and is shown to refute incorrect physics if imposed. This work encourages chemists to embed their domain knowledge into machine learning models to start a new paradigm of chemistry-informed machine learning for better accountability, interpretability, and generalization.
Variability in the distinctive features of silica sands in Central Europe
(MDPI, 2024) Bašistová, Martina; Vontorová, Jiřina; Zlá, Simona; Kawuloková, Monika; Lichý, Petr; Dvorský, Tomáš
Quality quartz sand is globally utilized in construction due to its availability and economic factors, especially in the production of composite cements. Despite its positive properties, quartz sand also has several disadvantages. The dilation of quartz sand can be technologically significant for certain high-temperature applications. This dilation has a non-continuous character with sharp volume change caused by the phase transformation from beta to alpha SiO2 at temperatures around 573 degrees C. The extent of dilation depends on various factors such as compaction, grain size, the quantity of sand, as well as the shape and character of the grain and chemical purity, particularly the SiO2 content. In this study, six types of quartz sand from different locations in Central Europe were examined, and the influence of chemical composition and grain shape was correlated with the final dilation of these samples. Evaluation methods included X-ray fluorescence spectroscopy (XRFS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), differential thermal analysis (DTA), and linear thermal expansion analysis. It was found that angular grains, despite their chemical purity, may exhibit minimal dilation. Conversely, the least suitable combination in terms of dilation appears to be a high SiO2 content and high roundness of grains with a smooth surface.
Synthesis of FeSi–FeAl composites from separately prepared FeSi and FeAl Alloys and their structure and properties
(MDPI, 2023) Novák, Pavel; Duda, Jiří; Průša, Filip; Skotnicová, Kateřina; Szurman, Ivo; Smetana, Bedřich
Composites consisting of iron aluminide and iron silicide phases were studied in this work. Powders of iron aluminide and iron silicide were prepared by mechanical alloying separately. Subsequently, they were blended in three different proportions and sintered by the SPS method under various conditions. After sintering, the composites are composed of FeAl and amounts of other silicides (Fe5Si3 and Fe3Si). Ternary Fe–Al–Si phases were not determined, even though their presence was predicted by DFT calculations. This disagreement was explained by steric factors, i.e., by differences in the space lattice of the present phases. Hardness and tribological properties were measured on composites with various weight ratios of iron aluminide and iron silicide. The results show that sintered silicides with the matrix composed of iron aluminide reach comparable hardness to tool steels. The composites with higher mass ratios of iron aluminide than silicide have higher hardness and better tribological properties.
Wetting of graphite and platinum substrate by oxide system with graded B2O3 content
(MDPI, 2023) Novák, Dalibor; Řeháčková, Lenka; Novák, Vlastimil; Matýsek, Dalibor; Peikertová, Pavlína
This work focuses on wetting two types of substrates (a platinum substrate and a polished graphite substrate) by molten polycomponent oxide system CaO–MgO–SiO2–Al2O3–B2O3 to test the level of interaction at high temperatures. The tested systems were subjected to high-temperature wetting tests in the temperature range from liquidus temperature to 1550 ◦C using the sessile drop method. A total of four oxide systems were tested with graded boron oxide contents ranging from 0 to 30 wt%. The experiments were conducted in a CLASIC high-temperature resistance observation furnace and an inert atmosphere of high-purity argon. Droplet silhouettes were obtained with a CANON EOS 550D high-resolution camera during heat treatment, with reactive and non-reactive wetting occurring depending on the substrate type. The dependence of the average wetting angles on temperature and time was evaluated, and it was found that boron oxide decreased the average wetting angles of molten oxide droplets. The analyses were accompanied by the SEM/EDX analysis of the substrate and FTIR analysis of the droplets after high-temperature experiments. The phase composition of the oxide systems was evaluated by XRD analysis.
2D/2D composites based on graphitic carbon nitride and MXenes for photocatalytic reactions: a critical review
(Springer Nature, 2023) Praus, Petr
The combination of the two-dimensional (2D) materials g-C3N4 and MXenes in photocatalysis offers several advantages. The g-C3N4 can serve as a visible light-absorbing material, while MXenes can enhance the charge separation and transfer processes leading to improved photocatalytic efficiency. A critical review of 77 already published articles in the field of photocatalytic reactions using g-C3N4 and MXenes, such as hydrogen evolution, the reduction of carbon dioxide, the degradation of organic compounds, the redox reactions of nitrogen, was conducted. For the purpose of greater objectivity, the published results were analysed by non-parametric Mann-Whitney, Kolmogorov-Smirnov, and Mood's median tests and visualised by box and whisker plots. It was found that MXenes can significantly improve the photocatalytic activity of g-C3N4. Adding other co-catalysts to the MXene/g-C3N4 composites does not bring a significant improvement in the photocatalytic performance. Promising results were obtained especially in the fields of hydrogen evolution and the reduction of carbon dioxide. Since the MXenes are relatively a new class of materials, there is still a big challenge for finding new photocatalytic applications and for the enhancement of existing photocatalytic systems based on g-C3N4, especially in terms of the MXenes and g-C3N4 surface and in the heterojunction engineering.
Graphitic carbon nitride/xylene soot metal-free nanocomposites for photocatalytic degradation of organic compounds
(Elsevier, 2023) Smýkalová, Aneta; Słowik, Grzegorz; Koštejn, Martin; Kawuloková, Monika; Foniok, Kryštof; Novák, Vlastimil; Praus, Petr
Graphitic carbon nitride and soot (g-C3N4/soot) metal-free nanocomposites were synthesized by a simple one-pot thermal synthesis from mixtures of dicyandiamide with different volumes of xylene. The soot nanoparticles of 17.7 ± 1.7 nm in size were observed on the g-C3N4 surface. The band gap energies of the synthesized nanocomposites decreased from 2.65 eV to 2.53 eV with the increasing content of soot nanoparticles. The photocatalytic activity of the g-C3N4/soot nanocomposites to degrade phenol, ofloxacin, and ampicillin under the LED irradiation of 420 nm was investigated. Time-resolved photoluminescence measurements, electrochemical impedance spectroscopy, and trapping experiments indicated that photoinduced electrons were accumulated in the soot particles, reacted with oxygen forming superoxide radicals, which decomposed the organic compounds. The degradation efficiency decreased in the sequence ofloxacin > ampicillin > phenol. The g-C3N4/soot nanocomposites were investigated for the photocatalytic degradation of organic compounds for the first time.
Maximizing the electrochemical performance of supercapacitor electrodes from plastic waste
(Elsevier, 2023) Dědek, Ivan; Bartusek, Stanislav; Dvořáček, Josef Jan; Nečas, Jan; Petruš, Josef; Jakubec, Petr; Kupka, Vojtěch; Otyepka, Michal
The management of the increasing volume of plastic waste has become a key challenge for society. A promising strategy now consists in the transformation of plastic waste into high-value materials that can be utilized in energy storage devices such as batteries and supercapacitors. In this study, we demonstrate a two-step procedure, involving pyrolysis, followed by chemical activation that will convert common plastic waste into activated carbons (ACs). This technique makes ACs suitable for supercapacitor electrode materials. Further, the electrochemical performance of ACs is outstanding in terms of capacitance, energy density, and cycling stability. Besides the well-established parameters, including a specific surface area and micropore volume, we found that other critical factors such as polymer glass transition temperature, polymer-activating agent miscibility, activating agent (K2CO3):AC ratio, and AC water dispersion stability also play a crucial role in determining the supercapacitors performance. Controlling these parameters, we obtained ACs as supercapacitor electrodes from a range of plastic waste materials with a competitive electrochemical performance. Specifically, the ACs exhibited a specific capacitance of 220 F g(-1) (at a current density of 1 A g(-1)), energy and power densities of 61.1 Wh kg(-1) and 36.9 kW kg(-1), respectively, and excellent cycling stability (95 % retention after 30,000 cycles). Our findings provide a pathway towards transforming plastic waste into valuable electrode materials for supercapacitors.
One-step synthesis of a sustainable carbon material for high performance supercapacitor and dye adsorption applications
(Elsevier, 2023) Manippady, Sai Rashmi; Michalska, Monika; Krajewski, Marcin; Bochenek, Kamil; Basista, Michał; Zaszczyńska, Angelika; Czeppe, Tomasz; Rogal, Łukasz; Jain, Amrita
The sustainable transformation of bio-waste into usable, material has gained great scientific interest. In this paper, we have presented preparation of an activated carbon material from a natural mushroom (Suillus boletus) and explor its properties for supercapacitor and dye adsorption applications. The produced cell exhibited a single electrode capacitance of-247 F g-1 with the energy and power density of-35 Wh kg-1 and 1.3 kW kg-1, respectively. The cell worked well for-20,000 cycles with-30% initial declination in capacitance. Three cells connected in series glowed a 2.0 V LED for-1.5 min. Moreover, ultrafast adsorption of methylene blue dye onto the prepared carbon as an adsorbent was recorded with-100% removal efficiency in an equilibrium time of three minutes. The performed tests indicate that the mushroom-derived activated carbon has the potential to become a high-performance electrode material for supercapacitors and an adsorbent for real-time wastewater treatment applications.
Adsorption and permeability of heavy metals (Fe, Cu, Pb, Zn, Cr, and Cd) onto the adaxial cuticle of Ficus elastica leaf
(Elsevier, 2023) Kovár, Filip; Smutná, Kateřina; Hruška, Adam; Koutník, Ivan; Vráblová, Martina
Air pollution represents a serious worldwide problem as atmospheric deposition of pollutants widely affects human and wildlife health. Heavy metals are significant pollutants with high toxicity, persistence, and bioaccumulation. In an environment polluted by industry and transportation, deposits of heavy metals on the leaves and their subsequent uptake by the plant occur. The leaf cuticle is the most important barrier between plant tissue and the atmosphere. To understand the processes of adsorption of heavy metals and their diffusion into the leaf, adaxial cuticles of Ficus elastica were enzymatically isolated and used in batch adsorption experiments and permeability measurements using diffusion chambers. A demonstration experiment with a whole leaf was also carried out, which pointed to the real uptake of metals by the leaf. Cuticles were subjected to characterization by methods of elemental analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. In the adsorption experiment, significant differences in the maximum adsorption capacity (Cd>Pb>Cr>Fe>Cu>Zn), and mechanism of adsorption (Langmuir model for Fe and Cr, Freundlich model for Zn, Cu, Pb, and Cd) were found. The permeability of intact adaxial cuticle for studied heavy metals did not differ significantly. The extent of foliar uptake differed between metals, with the relatively highest uptake of Fe and Zn. The transport of metals in the leaf was also observed. It seems that adsorption to the leaf surface more than the permeability of the cuticle is a limiting factor for foliar uptake of heavy metals from atmospheric deposits.

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