The content of this study discusses the kinetic issues of hydrogen evolution on metallic surfaces. For this purpose, the electrochemical deposition of Ni, Co, and Co-Ni alloy coatings from chloride baths on chromium-nickel steel (304) substrates was conducted. The deposited materials were then used as the cathode for electrolytic hydrogen evolution. Due to differences in electrochemical reaction mechanisms, the studies were carried out in acidic (0.5 M H₂SO₄) and alkaline (1 M NaOH) environments. Using different polarization rates (0.05; 0.1; 0.2; 0.5; 1; 2 V/s), cyclic voltammetry (CV) curves were recorded, showing the current intensity as a function of potential. Based on the experimental H₂ evolution curves and the ESTYM_PDE program, a mathematical model was developed to determine the parameters of the hydrogen evolution reaction (HER) on the metal and alloy coatings.

In this study, the phenomenon of mixing power increase when emptying tanks with an operating propeller impeller was examined. The tests were carried out for impellers with wide and narrow blades in two geometrically similar tanks with diameters T = 545 mm and T = 300 mm equipped with four standard baffles. The varied mixing power during tank emptying was examined on a larger scale, and on a scale of T = 300 mm the distribution of axial and radial velocities in the vertical r - z plane was determined using the PIV system. A very large increase in mixing power was found when the liquid-free surface being lowered was close to the upper surface of the blades. In the limit case, as much as a three-fold increase in mixing power was observed compared to the mixing power in a tank completely filled. It was found that the increase in mixing power was caused by a change in the mode of liquid circulation in the mixing tank when the liquid surface approached the impeller area. Correlation equations determining the values of the mixing power increase factor φ depending on the geometric parameters of the impeller and the Froude number are given. The φ values for propeller impellers were compared with similar values obtained for other types of impellers.

The work concerned the preparation of catalytically active copper oxides by electrochemical oxidation. The obtained catalysts were tested for the oxidation of methane with a concentration below 1% vol. in the air.

Dry reforming of methane is one of the stages of producing dimethyl ether, an interesting alternative to diesel fuel. The main problem in dry reforming of methane is the deposition of carbon on the catalyst. This process blocks the catalyst and thus leads to the need for its regeneration or replacement. Therefore, mathematical modelling to determine the conditions of reforming is a key issue that helps to determine the appropriate conditions for the process. In this work, two issues were focused on. The first issue concerned determining the conditions of the reactor wall temperature T_wall and the total pressure P_total at which the reaction is carried out on the degrees of methane and carbon dioxide conversion. The second issue concerned the influence of T_wall and P_total on the total mass of carbon deposited on the catalyst. Another goal of this article was to determine the reactor operating conditions in which the deposition of carbon is significantly lower.

This work presents a method for the preparation of zirconia-silica monoliths with improved porosity and their application in a continuous-flow system for cascade deacetalization and Knoevenagel condensation reactions carried out in two microreactors connected in series. The post-synthesis treatment of pristine micro/macroporous zirconiasilica monoliths, obtained by one step method, with the use of ammonia and sulfuric acid solutions resulted in mesoporous materials and improved macroporosity. They showed high activity in the deacetalization reaction of benzaldehyde dimethyl acetal, despite a relatively low zirconium content, ca. 0.3 wt.%, probably due to the formation of small quantities of the zirconium sulphate superacid. The Knoevenagel condensation reaction of benzaldehyde with ethyl cyanoacetate was performed in an amine-functionalised microreactor. The cascade process resulted in an 80% yield of ethyl cyanocinnamate and a very high selectivity that reached 99%. The flow resistance and residence time distribution were determined for both reactors.

The catalytic oxidation of arabinose to arabinonic acid was investigated in a recycled packed bed reactor to address pH control issues in continuous processes. Packed bed reactors are pivotal in the valorization of biomass, making the shift from batch to continuous systems critical for industrial applications. The setup used 2.1% Au/γ-alumina catalyst extrudates and incorporated a tandem reactor system with a liquid recycling loop to maintain a controlled pH of 8, ensuring optimal reaction conditions. Experiments were conducted at a reactor temperature of 70 °C, with liquid flow rates of 40 and 70 mL/min. The results demonstrated that the liquid flow rate significantly influences the arabinonic acid production, particularly during the initial stages, where the overall reaction rate is flow rate dependent. The higher flow rate (70 mL/min) resulted in faster arabinonic acid formation, attributed to increased reactant-catalyst contact and improved mass transfer, which also mitigated potential catalyst deactivation. These findings highlight the importance of flow rate optimization for enhanced sugar acid yields in continuous reactor systems and underscore the need for further research to optimize the reactor design and operation.

The production of biohydrogen from food waste (FW) by dark fermentation (DF) is a promising technology for commercialisation, as it is both a clean fuel and a suitable means of sustainable waste management. The described experiments compared the biohydrogen production yields obtained after the use of inoculum from two different sources: digested sludge from the wastewater treatment plant (WWTP) in Lodz and sludge from the anaerobic treatment of dairy industry wastewater (DIW) (unconcentrated and double-concentrated). In addition, the effect of different temperatures (70, 90 and 121°C) of inoculum pretreatment on the biohydrogen production in DF was tested. The process was carried out batchwise at 37°C. The highest yield of hydrogen production was obtained after the inoculum pretreatment at 70°C. In addition, a higher amount of hydrogen could be obtained by using sludge from the WWTP as the inoculum (96 cm3 H2/gTVSFW) than unthickened sludge from the DIW (85 cm ³ H ₂/g _TVSFW). However, after thickening the sludge from the dairy industry, and at the same time balancing the dry matter of both sludges, the hydrogen production potential was comparable for bothsludges (for the WWTP sludge – 96 and for the DIW sludge – 93 cm ³ H ₂/g _TVSFW). The kinetics of hydrogen production was described by modified Gompertz equation, which showed a good fit (determination coefficient R2 between 0.909 and 0.999) to the experimental data.

The large diversity of chemical substances present in air, water, or soil makes it necessary tostudy their mutual impact on the effectiveness of microbiological decomposition ofcontaminants. This publication presents the results of the studies aimed at evaluating the effect of two biogenic heavy metals - zinc and copper - on the phenol biodegradation by the Stenotrophomonas maltophilia KB2 strain. The tests were carried out for concentrations ofmetals significantly exceeding the legally permitted wastewater values: for zinc up to13.3 g·m ^-3, and copper up to 3.33 g·m ^-3. In the tested metal concentration range, phenol biodegradation by the S. maltophilia KB2 strain was not significantly influenced by theintroduced dose of zinc. While the presence of copper inhibited both biomass growth andsubstrate degradation. Kinetic data of metal and phenol mixtures were analyzed and very goodcorrelations were obtained for the proposed equations. An equation consistents with the Hanand Levenspiel model was proposed for the system S. maltophilia KB2-phenol-copper, whilean equation consistents with the Kai model for the system St. maltophilia KB2-phenol-zinc. The simultaneous presence of Zn and Cu ions in the culture resulted in a stronger inhibition ofphenol biodegradation.

Various types of events and emergency situations have a significant impact on the safety of people and the environment. This especially refers to the incidents involving the emission of pollutants, such as ammonia, into the atmosphere. The article presents the concept of combining unmanned aerial vehicles with contamination plume modelling. Such a solution allows for mapping negative effects of ammonia release caused by the damage to a tank (with set parameters) during its transport as well as by the point leakage (such as unsealing in the installation). Simulation based on the ALOHA model makes it possible to indicate the direction of pollution spread and constitutes the basis for taking action. And, the use of a drone allows to control contamination in real time and verify the probability of a threat occurring in a given area.

At the design stage of heat exchange installation used for gas conversion it is required to test the stability of the installation operation for the expected variable heat loads. For this purpose, a numerical model of the installation can be used. The paper presents an original concept of modelling the operation of heat exchange installations for randomly changing temperatures. Accumulation elements with lumped parameters were used in the model, which significantly facilitates the definition of model parameters and the calculation itself at the design stage. Due to the randomly changing temperatures supplying the accumulation element by the heating medium and the non-linear nature of the functions used in the calculation model, the iterative procedure was used for calculations. The process of validation of the proposed computational model of the accumulation element with lumped parameters was carried out for a water installation powered by a natural gas-fired boiler. The obtained results showed very good accuracy of the applied approach, the root mean square error for tested data has reached 1°C to 3°C, depending on the analysed case.

Hydrogen has been identified as an essential component of a decarbonized and sustainable energy system. The use of hydrogen is associated with the problem of its storage and distribution. Storing hydrogen in the gaseous state is energy-consuming, mainly due to the process of its compression. A much higher density of hydrogen can be obtained after its liquefaction. Hydrogen can also bond in chemical compounds, for example, in ammonia which contains 17.8% hydrogen by weight. The aim of the work was to examine the ammonia decomposition process in the plasma-catalytic system and to determine the effect of the process parameters on energy consumption. The applied catalysts allowed higher ammonia conversion than the homogeneous system. The lowest energy consumption, 593 kJ/molH2, was obtained for the 10% Fe/Al₂O₃ catalyst. The highest ammonia conversion (approx. 90%) was obtained using the 10% Co/Al₂O₃ catalyst.

The paper presents a novel, low-cost and simple route for synthesis of TiOF₂/CuO and F-TiO₂/CuO out of fluoride solutions. The obtained materials after calcination can be used in various photocatalytic applications, e.g. in water treatment. It was demonstrated that control of synthesis process parameters, such as pH, allowed for synthesis of particles with different phase composition and properties. Thus, pH≤4 environment had created conditions for formation of two structures of TiOF₂, hexagonal and cubic ones, as well as CuTiF₆(H₂O)₄. Increase of Cu content promoted increase of the cubic c-TiOF₂ phase. When the solutions exhibited pH>5, the synthesized particles consisted of (NH₄)₂TiF₆·2H₂O, (NH₄)₃TiF₇, and (NH₄)₂СuF₄·4H₂O. Calcination above 300 °С provided formation of TiOF₂/CuO particles, while elevated temperatures of 600 °С ensured appearance of F-TiO₂/CuO material. It was found that higher copper concentrations resulted with higher fluoride percentage after calcination at 600 °С. It was also demonstrated that F-TiO₂/CuO particles synthesized at рН≤4 exhibited energy band gap Eg of 3.3–3.25 eV, which decreased down to 2.85 eV for higher copper(II) oxide concentrations of 10 wt.%. Notably, the particles F-TiO₂/CuO synthesized at pH>5 exhibited band gap Eg of 3.4–3.5 eV, which decreased down to 2.9 eV for higher CuO concentrations.

This work aims at investigating the influence of the initial concentrations of carbon (glucose) and organic nitrogen (yeast extract) sources on Streptomyces rimosus ATCC10970 secondary metabolism in the stirred tank bioreactors. Additionally, glucose utilisation, biomass formation, pH, redox potential and dissolved oxygen levels, and the morphological development of S. rimosus pseudomycelium were studied. Eighteen secondary metabolites were detected by mass spectrometry and identified with the use of the authentic standard, or putatively with the use of literature and database of secondary metabolites. Varied initial yeast extract concentration acted much stronger on the formation of secondary metabolites than glucose did. For example, oxytetracycline was not biosynthesised at high yeast extract concentration while the formation of three other metabolites was enhanced under these conditions. In the case of glucose its increasing initial concentration led to higher secondary metabolite levels with the exception of an unnamed angucycline. High initial yeast extract concentration also drastically changed S. rimosus pseudomycelial morphology from the pelleted to the dispersed one. Ultimately, the cultivation media with the varied initial levels of carbon and nitrogen sources were proved to have the marked effect on S. rimosus secondary metabolism and to be the simplest way to either induce or block the formation of the selected secondary metabolites.

Improvement of life quality, food production and sustainability requires search for better, efficient natural resources extracting methods, while minimizing environmental impact, which is determined by carbon and water footprint calculation. In order to counter global phenomena, it is necessary for food-producing chain to work together to take conscious action on environment. Restoring balance demands action to reduce greenhouse gas emissions and rational water use, by reducing energy intensive processes or increasing efficiency of wastewater treatment methods. This requires a thorough understanding of all phenomena that determine a given process. Viscous fingering occurs during such processes as enhanced oil recovery, metal crystallization in batteries, sugar refining, groundwater purification and many others. Research to improve knowledge of this phenomenon and ability to predict its effects is crucial in development of basic industrial processes. This paper presents an experimental study of tracking immiscible viscous fingering in modified Hele-Shaw cells filled with a granular bed of known parameters. The influence of bed parameters and flow conditions on the observed phenomenon was investigated. During the tests, beds with the following grain diameter ranges were used: 200–300, 300–400 and 400–600 μm; the liquid was injected at three different flow rates in the range of 100–400 ml/h. On the basis of carried out work, a model of the studied phenomenon was proposed, which made it possible to determine the extent and the fingering scale.

The demand of energy and the search for alternative energy sources are the reason why scientists are interested in starch hydrolysis. The aim of the work was to experimental study of the hydrolysis of starch by α–amylase from porcine pancreas with α–amylase deactivation. Based on the experiments data, the parameters of starch hydrolysis by α– amylase with deactivation of enzyme was estimated. A mathematical model of temperature impact on the activity of α–amylase from porcine pancreas was used. It has been estimated that the activation energy E_a and the deactivation energy E_d were equal to 66 ± 4 kJ/mol and 161 ± 12 kJ/mol, respectively. Additionally, specific constant of starch hydrolysis k ₀ and specific constant of α–amylase deactivation k _d0 were calculated. The optimum temperature T_opt equal to 318 ± 0.5 K was obtained from mathematical model. The obtained values of E_a, E_d, k ₀ and k _d0 parameters were used to the model starch hydrolysis by α–amylase from porcine pancreas at 310 K and 333 K.

This study focuses on intensifying photocatalytic hydrogen generation from glycerol under natural sunlight, examining the effects of cocatalysts and solar applicability. Cocatalysts are commonly employed to enhance the separation of photo-generated charges, while sacrificial agents suppress electron-hole recombination. Utilizing crude glycerol and solar light for photocatalytic hydrogen generation presents a promising avenue. The main objective was to enhance H2 production from a glycerol-containing solution by selecting parameters and scaling up the process using various reactor types and research systems. The study investigated the applicability of natural sunlight for photocatalytic H2 production and examined the influence of organic impurities on H2 production from synthetic and real crude glycerol. Scaling up the process intensified the rate of hydrogen generation, with the highest production achieved using TiO2 loaded with 0.5% Pt under visible light irradiation. It was concluded that H2 can be generated by reducing protons from both water and glycerol, the sacrificial agent. Glycerol and water, in the presence of photodeposited Pt or Pd on TiO2 and light, are converted to H2 through photocatalytic water-splitting and light-induced oxidation of glycerol. The successful application of photocatalysts under natural sunlight for hydrogen production was confirmed, highlighting the potential for sustainable and scalable green hydrogen generation.

The article presents a novel solution based on dairy wastewater sorption on a biochar substrate obtained through thermal decomposition of Chlorella sp. algae biomass. The algal biomass obtained in the culture medium containing wastewater from dairy production was separated from the culture medium through sedimentation and centrifugation and then freeze-dried. After freeze-drying, the dry biomass was pyrolysed at 600 °C in a CO ₂ atmosphere.The EDS analysis showed that the oxygen-tocarbon (O/C) and nitrogen-to-carbon (N/C) ratios in the obtained material averaged 0.24 and 0.54 respectively. The arrangement and structure of the obtained biochar was evaluated using Raman spectroscopy. The observed spectra revealed the presence of D bands located at 1346–1354 cm ^-1 and corresponding to disordered carbon structures, as well as G bands located at 1585–1594 cm ^-1 and corresponding to tensile vibrations. The D/G intensity ratio was determined at 0.28. The next phase of the research involved sorption of dairy wastewater from cleaning processes containing 1 g of the obtained biochar using solid phase extraction. The study results confirmed high sorption efficiency of the obtained algal biochar. Turbidity was reduced by 93%, suspension by 88%, sulphates by 61%, chlorides by 80%, and organic carbon by 17%. The research confirmed the possibility of using wastewater from dairy production as a natural culture medium for Chlorella sp. algae cultivation to manufacture valuable biochar, which could be used as a sorption bed in the treatment of dairy wastewater from cleaning processes.

The deacetylation process of chitin or chitosan is carried out on industrial scale by chemical reaction with concentrated NaOH or KOH solution, but an enzymatic process is also possible. Enzymatic deacetylation with chitin deacetylase (EC 3.5.1.41) is non-destructive for polymer chains, and that is why recently it has been investigated more intensively. The structure of the enzyme is important information as it helps to better understand the enzyme action. Chitin deacetylase's primary and secondary structures were presented in literature and were the basis for the mathematical modelling of the 3D tertiary structure. However, the mathematical model for the activity centre has never been confirmed experimentally. This paper presents the experimental confirmation of a computer modelling of the catalytic residues in the activity centre of extracellular chitin deacetylase from Absidia coerulea vel orchidis. Based on kinetic studies, amino acids responsible for enzyme activity were determined experimentally as aspartic acid and glutamic acid or as two aspartic acid residues.

The paper focused on the co-production of high-value-added product thermostable C-phycocyanin (C-PC) and biomass, further utilized in pyrolysis. The photobiosynthesis of CPC was carried out by the thermophilic cyanobacteria Synechococcus PCC6715 cultivated in the helical and flat panel photobioreactors (PBR). Despite the application of different inorganic carbon sources, both PBRs were characterized by the same growth efficiency and similar C-PC concentration in biomass. To release the intracellular C-PC the biomass was concentrated and disintegrated by the freeze-thaw method. The crude C-PC was then further purified by foam fractionation (FF), aqueous two-phase extraction (ATPE), membrane techniques (UF) and fast protein liquid chromatography (FPLC). Each of the tested methods can be used separately; however, from a practical and economic point of view, a three-stage purification system (FF, FPLC and UF) was proposed. The purity ratio of the final C-PC was about 3.9, which allows it to be classified as a reactive grade. To improve the profitability of 3G biorefinery, the solid biomass residue was used as a substrate to pyrolysis process, which leads to production of additional chemicals in the form of oils, gas (containing e.g. H ₂) and biochar.

These studies were carried out within the framework of the European FuelSOME Project (No. 101069828), which focuses on establishing a multi-fuel energy generation system based on utilization of Solid Oxide Fuel Cells (SOFC) and is dedicated mainly to the long-distance maritime shipping. For the SOFC stacks, the removal of sulphur contaminations from fuels is crucial as the content of sulphur compounds is strictly limited, even to dozens of mol ppb. The modelling and calculations were performed for a selected testing system of deep adsorptive purification of methanol to remove dibenzothiophene (DBT) on activated carbon (AC), where DBT was taken as a representative of compounds contaminating sulphur. An appropriate model of the adsorption column packed with activated carbon pellets was elaborated as a basis for process simulations and further techno-economic considerations. The research focused on modelling sulphur removal to achieve the required purity of methanol, then on cost analysis to optimize the proposed purification process. At the current stage, the aim of the performed studies was a preliminary check of a possibility of successfully performing deep adsorptive desulphurisation of methanol and an estimation of purification costs.

Plastics have become indispensable in everyday life due to their properties. For this reason, the accumulation of polymer waste in the natural environment is becoming a serious global problem. The aim of the research was to isolate microorganisms capable of biodegrading plastics. The studies focused on the biodegradation of low-density polyethylene as the most common polymer. Seven and five bacterial strains were isolated from the landfill and compost, respectively. The morphological and biochemical characteristics of the isolates were determined. These isolates were able to survive in an environment where the only carbon source was LDPE, but no increase in biomass was obtained. However, analysis of the spectra obtained by the ATR-FTIR method showed the formation of chemical changes on the polymer surface. Bacterial biofilm formation was visualized by scanning electron microscopy. The toxicity of plastic biodegradation products in a liquid environment was tested and their safety for plants was confirmed. However, these biodegradation products have acute lethal toxicity for the Daphnia magna.
LDPE films were pre-treated with H ₂O ₂, HNO ₃, or heat. The biodegradation of HNO ₃-treated LDPE by isolated bacteria was the most significant. The weight loss was approximately 8%, and 6%, for landfill and compost-isolated bacterial strains, respectively.

The effects of leachates from newly-synthesized bioplastics on the early stages of higher plant growth were studied together with the putative identification of the chemicals in the given microbioplastic leachates. Three polylactide-based bioplastics and pure polylactide (PLA) were subjected to the phytotoxicity tests (1) to determine the intrinsic effects of chemicals on the germination and early growth of plants without prior incorporation of the chemicals into a soil and (2) to find the impact of the chemicals introduced into a soil on the germination and plant growth. Plants Sorghum saccharatum, Lepidium sativum and Sinapis alba were used. For two out of four microbioplastics the total ion chromatograms revealed the presence of chemicals in the leachates. Out of 20 individual m/z values, 6 were putatively attributed to the known compounds. Microbioplastic leachates did not affect seed germination and contributed rather to the stimulation than inhibition of the early plant growth. In the soil tests the inhibition of root and shoot growth of dicotyledons occurred more frequently than in the liquid phase tests. It indicates the potential interactions between the chemicals in the leachates and soil matrix. Dicotyledons were more sensitive than monocotyledons in the evaluation of phytotoxicity of microbioplastic leachates.

This paper presents the development of a multiphase aerodynamic reactor designed for multi-component systems, focusing on precise catalyst dosing in the combustion chamber. The study aims to underscore the significance of this work by emphasizing the critical role of optimized operational conditions in enhancing the transportation of the modifier for combustion processes. Through comprehensive numerical simulations and experimental tests, this research explores the impact of parameters such as flow rates of the dosed substance and air, dosing nozzle outlet diameter, and conduit diameter on the flow rate and trajectory of the transported modifier. The findings highlight the importance of a minimum droplet diameter of 30 μm, preferably 50 μm, for proper delivery to the combustion chamber. This study not only identifies key differences between analyzed structures but also emphasizes the crucial role of these operational parameters in achieving optimal conditions for modifier transport.

Electrospun carbon nanofibers (CNFs) are an excellent material which can possess a wide range of properties through controlling the parameters of the electrospinning process, as well as through thermal treatment. At the same time, CNFs are an excellent substrate for carrying out modifications, both volumetric, at the stage of precursor preparation, and surface modifications. Different methods of introducing various silicon carbide (SiC) precursors into the spinning solution enables the formation of needleshaped SiC nanostructures on the CNF surface. This work presents an attempt to obtain nanofibrous carbon materials modified in volume and on the surface with SiC precursors, along with their characteristics. The most promising method of creating needle-like SiC nanostructures on the surface of CNFs is the use of volume modification with polysiloxane and silanization of the surface of the CNFs in a organosilicon sol solution.