Hydrogen storage properties of MgH2-Ni system

The effect of pure Ni addition (5 wt.%) in MgH2 powder was investigated mechanochemically for short milling times (15, 30, and 45 min). Obtained MgH2-Ni system was characterized by XRD, SEM-EDS, PSD, DSC, and TPD. Compared to pure MgH2, uniform distribution of nickel reduces the temperature of H2 desorption by more than 100 °C. It is shown that influence of two important processes, grinding and catalysis, may be followed separately. We can conclude that the catalysis of H2 desorption by Ni particles on MgH2 matrix is the dominant effect for the investigated short milling times.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Effect of metalic and metal-oxide catalysts on LiAlH4 decomposition

Metal and complex light hydrides are the best fitted materials for hydrogen storage within the concept of hydrogen based economy [1]. They meet the basic application requirements: low-cost, safety and they are environmentally friendly. Beside their benefits, as relatively stable compounds, these materials exhibit also some undesirable properties like sluggish kinetics and high temperature of hydrogen desorption. LiAlH4 has emerged as a potential material for solid-state hydrogen storage because of its high hydrogen gravimetric capacity (10.5 wt%). It decomposes in three steps, according to the reactions [2]: 3LiAlH4 → Li3AlH6 + 2Al + H2 (R1) Li3AlH6 → 3LiH + Al + 3/2H2 (R2) 3LiH+3Al → 3LiAl + 3/2H2 (R3) The temperature of the first reaction is between 150-175°C, of the second between 180-220°C and the third between 400420°C. The first two reactions (R1 and R2) are very important from the hydrogen storage point of view: (i) both take place at a reasonable low temperatures and (ii) overall sum of theirs gravimetric hydrogen capacity is 7.8 wt.%, so the reactions (R1) and (R2) are accessible for practical hydrogen storage. However, the slow dehydrogenation kinetics and irreversibility under moderate condition hinder its imminent application. Particle refinement and catalyst or additive introduction by mechanical milling led to the significant improvement of LiAlH4 hydrogen storage properties [2]. However, during the milling process, the temperature in the milling chamber can significantly increase reaching the temperature of R1 or even R2 leading to the degradation of hydride, change in the hydrogen desorption mechanism (figure 1) and decrease in the hydrogen storage capacity of material [3]. So, in this work the impact of metallic (V, Mn an Cr) and metal oxide (Fe2O3 and Nb2O5) additives on the LiAlH4 hydrogen desorption properties with the emphasis on the hydride degradation process during milling and a consequent hydrogen desorption reaction mechanism was studied. The aim was to improve the hydrogen desorption kinetics without hydrogen capacity deterioration.6th International Symposium on Materials for Energy Storage and Conversion : July 5-8, Bol, island of Brač, Croatia, 2022

Effect of different sodium butyrate levels in weaned pig diet on the antioxidant capacity of selected organs

The aim of this study was to evaluate the influence of different sodium butyrate levels on the antioxidant capacity of selected organs (liver and kidney) in pigs. The study was conducted on 48 weaned piglets (28 to 54 days old) fed one of three diets (group C had no added sodium butyrate, group E-I had 3 g and group E-II 5 g of sodium butyrate added per kg of diet). The guaiacol peroxidase and pyrogallol peroxidase activities in liver tissues of E-II pigs were significantly lower than those in E-I pigs, while the activities of these enzymes in kidney tissues were significantly lower than in control pigs for both butyrate levels. Glutathione peroxidase activity in liver tissues was not upregulated by either level of dietary sodium butyrate. Also, the contents of malondialdehyde, indicative of lipid peroxidation, were not significantly different among the pig dietary groups. No significant differences in the enzyme activities (catalase, superoxide dismutase, glutathione S-transferase or the oxidation product, reduced glutathione) of control pigs and of animals consuming 3 g or 5 g sodium butyrate per kg of diet was found. The results showed that oral administration of sodium butyrate had an impact only on guaiacol peroxidase and pyrogallol peroxidase enzyme activities

Mechanochemical activation of LiAlH4-Fe2O3 composites-a method to enhance kinetics of hydrogen desorption

Mechanical milling of pure lithium alanate (LiAlH4) was done with addition of 5 weigh percent of Fe2O3 using different milling time ranging from 1 to 15 minutes [1]. Mechanical milling of composites causes destabilization of LiAlH4 structure as it observed by XRD measurements. Particle size distribution results reveals that composite particle size decrease with milling time up to 3 minutes, and then increase almost to the original size, for 15 min sample. Mechanical mailing cause phase transformation from AlH4- to AlH63-. As a consequence of structural and chemical changes, desorption properties of composites are change kinetic of desorption is improved in comparison to unmilled LiAlH4. The shifting of hydrogen desorption temperature to lower temperatures is observed together with change from multi-step desorption to one-step hydrogen desorption is also observed. This caused decrease in activation energy of composites from Ea = 665 kJ/mol for unmilled LiAlH4, Ea = 279 kJ/mol for 3 min milled composite.Solid-State Science & Research ; 10-11th June 2021, Onlin

Efficacy of diatomaceous earth in controlling major store product pests: Plodia interpunctella, Tribolium confusum and Acanthosclides obtectus

Diatomaceous earth (DE) is a dust formed from fossilized skeletal remains of single-celled algae – diatoms. Diatoms have a fine skeleton made of amorphous silicon dioxide (SiO2), as a major constituent of DE, which additionally contains minor amounts of minerals (aluminium, iron oxide, calcium hydroxide, magnesium and sodium). Insecticidal activity of DE is a result of desiccation that occurs after the particles of DE absorb the waterproof lipids from the arthropod cuticle (destroy epicuticular lipid layers) leading to high rate of water loss. Efficacy of DE depends on chemical composition, particle size and geographic origin. This work aimed to assess the efficacy of DE originating from Kolubara open-pit mine, Serbia, in comparison to commercially available preparation SilicoSec®. Efficacy was assessed in contact toxicity test, against indian meal moth (Plodia interpunctella) larvae and confused beetle (Tribolium confusum) and bean weevil (Acanthoscelides obtectus) adults. DEs were applied at rates: 5, 10, 15 and 20 mg-2 and mortality was recorded after 24, 48, 72 h and seven days

Knowledge, attitudes and dietary practices of pharmacy students regarding the importance of nuts consumption

Nuts are nutrient-dense foods with complex matrices rich in unsaturated fatty acids and other bioactive compounds. Numerous reported health benefits of nuts may be attributed to their unique nutrient profiles and synergistic interaction of their constituents, including macronutrients, micronutrients and phytochemicals. The objective of this study was to explore pharmacy students’ nuts consumption practice, as well as their attitudes and knowledge concerning nuts nutritional and health properties. A cross-sectional survey based on the online self-administered questionnaire, was conducted in September 2020. Among respondents (n=136, 90.4% female and 9.6% male, mean age 23.7±2.0 years), more than half agreed or strongly agreed that regular consumption of nuts might have beneficial effects on health, including reducing the risk of cardiovascular disease. Furthermore, the majority of participants perceived nuts as healthy sources of proteins and monounsaturated and polyunsaturated fats. The most common reason cited by respondents for eating nuts were taste (80.2%), followed by health effects (53.1%) and nutrient profiles (45.0%). The most commonly consumed nuts among pharmacy students were almonds (35.2%) and peanuts (28.4%), followed by hazelnuts (19.1%) and walnuts (15.6%). Based on self-reported data, students predominantly consume raw nuts (54.0%) as a snack between meals (78.5%). Nutrition-related courses within the faculty curriculum were the main sources of acquiring information regarding the beneficial effects nuts exert on health outcomes. Although certain gaps in knowledge were determined, in most senior students, the attitudes and dietary practices regarding the consumption of nuts were at an adequate level. Nevertheless, expanded efforts and additional educational programs may be useful in strengthening the capacities of these future health professionals for providing adequate nutrition advice and proactive advocacy of nuts health benefits.UNIFood2021 Conference, 24th-25th September 2021 University of Belgrade, 2nd International UNIfood Conferenc

The Catalytic Effect of Vanadium on Sorption Properties of MgH2-Based Nanocomposites Obtained Using Low Milling Time

The effects of catalysis using vanadium as an additive (2 and 5 wt.%) in a high-energy ball mill on composite desorption properties were examined. The influence of microstructure on the dehydration temperature and hydrogen desorption kinetics was monitored. Morphological and microstructural studies of the synthesized sample were performed by X-ray diffraction (XRD), laser particle size distribution (PSD), and scanning electron microscopy (SEM) methods, while differential scanning calorimetry (DSC) determined thermal properties. To further access amorph species in the milling blend, the absorption spectra were obtained by FTIR-ATR analysis (Fourier transform infrared spectroscopy attenuated total reflection). The results show lower apparent activation energy (Eapp) and H2 desorption temperature are obtained for milling bland with 5 wt.% added vanadium. The best explanation of hydrogen desorption reaction shows the Avrami-Erofeev model for parameter n = 4. Since the obtained value of apparent activation energy is close to the Mg-H bond-breaking energy, one can conclude that breaking this bond would be the rate-limiting step of the process

Kinetic behavior of MgH2-transition metal composites: towards hydrogen storage

Hydrogen as an energy vector represents great potential, due to its high gravimetric density and low mass, as well as the fact that combustion does not emit harmful chemical byproducts. Hydrogen has the highest energy density per unit mass compared to any other fuel but a rather low energy density per unit volume. Further, hydrogen storage is a key technology for developing a hydrogen and fuel cell-based economy [1]. Metal hydrides as alternative hydrogen carriers have a wide range of performance parameters such as operating temperature, sorption kinetics, activation conditions, cyclic options, and equilibrium hydrogen pressure. These parameters can be improved or adjusted to meet the technical requirements of different applications. The most commonly used method for hydride destabilization is nanostructuring by mechanical milling which leads to a reduction in the particle and crystallite size of the MgH2 powder. Nanostructuring is often combined with catalyst addition and composite formation [2,3]. The most of research is focused on the morphological, structural, and thermodynamic effects typical for long milling times, while in this work we have followed the changes taking place under short milling times. The thermal stability of magnesium hydride is related to - changes in the crystallites and powder particle size. The analysis also considered the changes in activation energy. MgH2-M composites were prepared by mechanical milling of the as-received MgH2 powder (Alfa Aesar, 98% purity) with the addition of 2 and 5 wt.% of M (M= V, W, Mo). Mechanical milling was performed in s SPEX 5100 Mixer Mill using 8mm diameter milling ball. Samples were milled for 15-45 minutes under the inert atmosphere of argon and a ball-to-powder ratio 10:1 Figure 1. shows the kinetic curves obtained for composites with 5wt% of vanadium. To investigate the desorption process in detail, different models of solid-state kinetics were used as implemented in the code developed in our group. The ratelimiting step of the desorption reaction was determined using the iso-conversional kinetic method due to better accuracy of obtained apparent activation energies. As shown in Table 1 a decrease in apparent activation energies has been observed. It is obvious that the sorption kinetics is affected by material preparation because the reactivity of magnesium with hydrogen is strongly modified by changes in several surface parameters that govern the chemisorption, the dissociation of molecular hydrogen, and hydride nucleation7th MESC-IS 2023 : International Symposium on Materials for Energy Storage and Conversion : 11th INESS : International Conference on Nanomaterials & Adv. Energy Storage Systems : October 7-10, Baku, 2023

Hydrogen storage properties of MgH2-Ni system

The effect of pure Ni addition (5 wt.%) in MgH2 powder was investigated mechanochemically for short milling times (15, 30, and 45 min). Obtained MgH2-Ni system was characterized by XRD, SEM-EDS, PSD, DSC, and TPD. Compared to pure MgH2, uniform distribution of nickel reduces the temperature of H2 desorption by more than 100 °C. It is shown that influence of two important processes, grinding and catalysis, may be followed separately. We can conclude that the catalysis of H2 desorption by Ni particles on MgH2 matrix is the dominant effect for the investigated short milling times