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Transition metal ion doped nanoanatase for photocatalytic and adsorption application
No full textTitanium(IV) oxide exists in three crystalline modifications: tetragonal anatase (I41/amd) and rutile (P42/mnm), and orthorhombic brookite (Pbca). TiO2 is a well-known material with extraordinary properties, which can be improved by doping. This work aimed to obtain transition metal ion doped TiO2 with better adsorption and photocatalytic properties compared to the undoped one. The hydrothermal treatment at 120 °C for 12 h was used to synthesize the undoped TiO2 from titanium(IV) isopropoxide. To obtain doped TiO2 samples with 5 at.% of the dopant (TiO2-Mn, TiO2-Cu, TiO2-V) the suitable precursor was added to the titanium(IV) isopropoxide: manganese(II) nitrate, copper(II) nitrate, and vanadium(V) oxytriisopropoxide. Hydrothermally obtained powders were calcined at 400 °C for 1 h (400-TiO2, 400-TiO2-Mn,400-TiO2-V, 400-TiO2-Cu). The final phase composition, crystallite sizes, and unit cell parameters were determined using the XRD data. Photocatalytic and adsorption properties were estimated toward removing azo dye Reactive Orange 16.
Nanoanatase, having distinctly small crystallites (7–12 nm), was formed in all samples, while in the case of Mn- and Cu-doped TiO2, the traces of brookite were present. The unit cell parameters of anatase are changed upon doping (a=(3.7799(2)–3.7934(2)) Å, c=(9.4936(7)–9.5157(6)) Å), pointing out that the dopants were incorporated in the structure. This is even more pronounced in the case of calcined samples (a = (3.7772(2)–3.8092(3)) Å, c = (9.4623(7)–9.5420(8)) Å). Regarding the ionic radius of dopants and the analysis of the lattice parameters, we assume that in the samples TiO2-Mn, 400-TiO2-Mn, and 400-TiO2-V, the Mn(II) (r = 0.670 Å) probably was oxidized to Mn(IV) (r=0.530 Å) during the hydrothermal treatment, while the V(V) (r = 0.540 Å) was reduced to V(III) (r = 0.640 Å) during the calcination.
The 400-TiO2 sample demonstrated the best photocatalytic activity by degrading 98 % of the dye after 120 min under simulated solar light, while the TiO2-Cu sample showed the best adsorption capacity, adsorbing even 71 % of the dye.Tитан(IV)-оксид се јавља у три кристалне модификације: тертрагоналнoм анатасу (I41/amd) и рутилу (P42/mnm) и ромбичном брукиту (Pbca). TiO2 је добро познат материјал изузетних својстава која се могу побољшати допирањем. Циљ овог истраживања било је добијање TiO2 допираног јонима прелазних метала са бољим адсорпционим и фотокаталитичким својствима у односу на недопиран TiO2. Недопирани TiO2 синтетисан је хидротермалним третманом на 120 °C током 12 h суспензије добијене хидролизом титан(IV)-изопропоксида. Узорци TiO2 са 5 at.% допанта (TiO2-Mn, TiO2-Cu, TiO2-V) добијени су под истим условима, уз додатак одговарајућег прекурсора титан(IV)-изопропоксиду: манган(II)-нитрата, бакар(II)-нитрата и ванадијум(V)-окситриизопропоксида. Хидротермално добијени прахови су калцинисани на 400 °C током 1 h (400-TiO2, 400-TiO2-Mn, 400-TiO2-V, 400-TiO2-Cu). Фазни састав, величина кристалита и параметри јединичне ћелије узорака су одређени на основу података прикупљених рендгенском дифракцијом. Фотокаталитичка и адсорпциона својства испитана су кроз уклањање азо боје реактивно наранџасте 16.
Наноанатас изразито малих кристалита (7–12 nm) добијен је у свим узорцима, док је код узорака допираних манганом и бакром брукит био присутан у траговима. С обзиром на уочену промену параметара јединичне ћелије анатаса код некалцинисаних узорака (a = (3,7799(2)–3,7934(2)) Å, c = (9,4936(7)–9,5157(6)) Å) у поређењу са недопираним TiO2, закључили смо да су се допанти уградили у структуру. Промена параметара јединичне ћелије је још уочљивија код узорака калцинисаних на 400 °C (a = (3,7772(2)–3,8092(3)) Å, c = (9,4623(7)–9,5420(8)) Å). Очекивано је да запремина јединичне ћелије анатаса зависи од величине допанта. Међутим, у нашем случају изузеци су TiO2-Mn, 400-TiO2-Mn и 400-TiO2-V што указује да се Mn(II) (r = 0,670 Å) вероватно оксидовао до Mn(IV) (r = 0,530 Å) током хидротермалног третмана, док се V(V) (r = 0,540 Å) редуковао до V(III) (r = 0,640 Å) током калцинације.
Најбољу фотокаталитичку активност показао је узорак 400-TiO2, разградивши 98 % боје након 120 min у присуству симулиране сунчеве светлости, док је TiO2-Cu демонстрирао најбољу адсорпциону моћ уклонивши чак 71 % боје
Risk analysis of investing in greenhouse vegetable production
No full textThis research aimed to investigate the risk analysis of investing in greenhouse vegetable
production, for the three most commonly cultivated species (tomato, cucumber, and pepper)
in the region of Bijeljina (Bosnia and Herzegovina). Data were collected from 35 family
farms using a face-to-face questionnaire (structure of production, type and area of protected
environment, and method of production with inputs and outputs). Results showed positive
financial results highlighting the tomato production to be more adaptable to changes in the
yield, variable and total cost considering the threshold of the economy obtained by the break-
even analysis. By using the Monte Carlo method, we analyzed the risk of the investment in
the covered systems with an equal share of tomato and cucumber in production under the
following assumptions: an investment in a protected area without additional heating of 4,000
m2, financed with credit from a bank with an interest rate of 4% per year, while incomes and
expenses arise at the end of the year. During the 10-year exploitation period, net cash flow
was positive and the net present value of the investment was 73,436.51 EUR, which indicates
that the investment is economically justified if the projected values of the net cash flow are
achieved. According to the Monte Carlo method, we found that the expected net present value
of investments was 57,649.89 and with 90% certainty, it can be concluded that the net present
value will be in the interval from 30,438.62 to 81,860.70 EUR
CRYSTALLOGRAPHIC AND QUANTUM CHEMICAL STUDIES OF 2,2’-DIPYRIDYLAMINE–DIETHYLBARBITURIC ACID CO-CRYSTAL
No full textThe diethyl derivative of barbituric acid (H2debarb) belongs to a class of drugs that have a wide
range of uses as sedatives, anticonvulsants, and anaesthetics. It is a strong hydrogen bond donor
via two –NH groups and a weak acceptor via three carbonyl O atoms.
2,2′-Dipyridylamine (dipya) is a charge-transferring organic base that can exist in a variety of
protonation states, adopting one of nine coordination modes. A co-crystal (H2debarb)(dipya)2,
was prepared by solvent evaporation method from the H2O/EtOH reaction mixture containing
Na(Hdebarb) and dipya in molar ratio 1:1. Single crystal X-ray analysis revealed that the
asymmetric unit of the co-crystal consists of one H2debarb and two dipya moieties linked by
strong N/C–H···O/N interactions. The main structural feature is a supramolecular tape formed by
N/C–H···O/N interactions, while weak π···π stacking interactions were observed between the
tapes. The calculation of the molecular electrostatic potential surfaces revealed the most
electrophilic and nucleophilic parts, while the Hirshfeld surfaces and 2D fingerprint plots
allowed the analysis of the intermolecular interactions and quantification of the contribution of
different intermolecular contacts present in the crystal structure of co-crystal.
Crystallographic data: C28H30N8O3, triclinic, P–1, a = 11.4015(5), b = 12.1485(4),
c = 12.1839(5) Å, α = 70.012(3), β = 64.655(4), γ = 64.500(4) °, V = 1350.68(11) Å3, Z = 2,
R1 = 0.0412, wR2 = 0.1012 for 352 parameters and 3835 observed reflections
SYNTHESIS AND CHARACTERIZATION OF LiTiO2 ADSORBENT
No full textTiO2-based nanomaterials, such as layered titanates, have attracted much attention due to their
potential applications in lithium batteries, photocatalysis, adsorption, and humidity sensors. To
obtain LiTiO2, nanoanatase powder was hydrothermally treated in 3 M LiOH at 120 ºC for
18 h. The sample was characterized by XRPD, TG/DTA, SEM, and UV-VIS analysis.
Nanoanatase showed high reactivity towards Li+
cations by forming the LiTiO2, which was
revealed by XRPD. The stability of the compound was confirmed by TG/DTA. The adsorption
capacity of the obtained LiTiO2 nanopowder towards the harmful industrial dye Ethyl Violet
(EV) was tested and compared with that of the activated carbon (AC), the most commonly used
adsorbent for the wastewater treatment. LiTiO2 showed even thirteen times more intensive
adsorption than the commercial AC by completely removing EV within 5 minutes, which opens
the chance for practical application of LiTiO2 in wastewater treatment
Hydroxyl radical scavenging activity of Dictamnus albus and Asplenium ceterach assessed by EPR spectroscopy
No full textOxidative stress plays a crucial role in the development of various diseases, and natural antioxidants are gaining attention for their potential therapeutic applications. In this study, we investigated the hydroxyl radical (•OH) scavenging activities of Dictamnus albus and Asplenium ceterach, two plants known for their traditional medicinal use and adaptation to harsh, dry environments. Hydroxyl radicals were generated via the Fenton reaction, and their scavenging by plant extracts was assessed using electron paramagnetic resonance (EPR) spectroscopy. The spin trap technique with DEPMPO as spin trap allowed for accurate detection of hydroxyl radicals and the quantification of their reduction by the plant extracts.
The EPR analysis revealed that Dictamnus albus was more effective in eliminating hydroxyl radicals, with a scavenging activity of 60.49%. Asplenium ceterach demonstrated moderate activity, eliminating 43.71% of the radicals. These findings suggest that Dictamnus albus and Asplenium ceterach possess significant antioxidant potential, which may contribute to their traditional medicinal use. Future work will focus on isolating and characterizing the active compounds responsible for these effects, as well as evaluating their efficacy in biological systems
Evaluation of 3D porous electrodes in a zero-gap cell for alkaline water electrolysis
No full textIn modern AWE systems, a zero-gap cell architecture is used where electrodes are directly pressed on the membrane to reduce the ohmic losses related to the electrolyte. This technology requires perforated plates or novel porous 3D electrodes. Additionally, at high H₂-production rates, the enormous gas evolution leads to losses which are related to the blocking effect of adherent gas bubbles and/or the increased electrolyte resistance [1]. In this regard, optimized porous structure is required which enables enhanced removal of gas bubbles and a direct flow to the backside of the electrodes resulting in high cell efficiency.
In this contribution, powder metallurgy route in combination with a space holder method [2,3] were used to produce novel porous 3D electrodes so called porous metal foil and porous sintered metal papers. Additionally, powder metallurgic modified porous metal foams were investigated. This approach allows to adjust the porosity, the thickness as well as the pore size of the catalytic material. Consequently, the accessible surface area of the electrode can be enhanced and the flow of gas bubbles through the porous structure can be optimized. The implementation of the porous electrodes in a zero-gap single cell were investigated with respect to the cell resistance, cell voltage and the pressure distribution on the separator. Here, the porous electrodes were used as anode, whereas electrodeposited Ni-Sn electrodes [4] or Raney-Ni electrodes [5] were utilized as cathode. Single cell measurements indicates that the efficiency at high current densities (up to 1 A cm³) is mainly related to the efficient gas bubble removal. Cell voltage of 1.83 V at 1 A cm³ was determined if an anode with an optimized pore structure is utilized.
Additionally, a single lab-electrolyzer was equipped with reference electrodes to get access to the half-cell potential with the objective to evaluate the cathode and anode in-operando [6]
CONCENTATION OF CYCLITOLS (POLYOLS) AND SUGARS IN ALFALFA
No full textCyclitols-polyols are plant metabolites that are usually neglected in animal nutrition because they do not contribute to the energy metabolism of animals. In recent years, several positive effects of these compounds on animals and humans have been demonstrated. D-pinitol is the most abundant cyclitol in alfalfa (Medicago sativa). To determine the content of D-pinitol in alfalfa, three alfalfa samples were taken at the beginning, middle and end of the growing season in the first three growing cycles. In almost all samples, the D-pinitol content was several times higher than the sugar content. The lowest D-pinitol content was 44.5 g/kg dry matter, while eight out of nine samples had a sugar content of less than 37 g/kg dry matter. The D-pinitol content found was significantly higher than reported in the literature. It was estimated that consumption of collected alfalfa samples by cows would result in an intake of a significantly higher dose of D-pinitol than the dose affecting blood glucose levels in laboratory rats. Further research is needed to determine whether the concentration of D-pinitol in alfalfa grown in Serbia is consistently high and how this concentration affects the health of the animals and their production results
Silicon differentially modifies leaf functional ionome and improves growth of oak seedlings subjected to combined biotic and abiotic stress
No full textSilicon (Si) has been extensively studied for its beneficial effects on plants under single-stress
conditions, yet its role in modifying plant response to simultaneous biotic and abiotic stress exposure, which is prevalent under natural conditions, remains underexplored. This study was conducted in the plant-pathogen-soil model system consisting of pedunculate oak (Quercus robur L.),
its root pathogenic oomycete Phytophthora plurivora, and limiting phosphorus (P) soil conditions.
We analysed the impact of Si supply on plant growth and leaf mineral nutrient element profile
(functional ionome) of oak seedlings subjected to biotic stress (P. plurivora root infection), abiotic
stress (low P), and their combination. The effect of Si on enhancing overall plant growth and root
health was most prominent under the most severe stress conditions (combined P deficiency and
root-pathogen infection), where it concomitantly influenced uptake and leaf accumulation of 10
out of 13 nutrients analyzed. Silicon treatment reversed the patterns of stress-induced changes for
the following nutrients: P, boron (B), and magnesium (Mg) under P deficiency; P, B, sulfur (S) under
pathogen attack, and nickel (Ni), and molybdenum (Mo) under the combined stress. Silicon also
affected some leaf nutrients that were not changed by a particular stress itself and decreased leaf
Mg levels under all the stresses. On the other hand, Si accumulation at adequate P supply was
increased by pathogen attack. This exploratory study indicates the complexity of nutrient crosstalk
in stressed plants, and opens more questions about genetic networks that control plant physiological responses under combined abiotic and biotic stresse
A conservative approach to 2SS modeling of KJc size effect in the transition region
No full textEnormous scatter of fracture toughness (KJc) experimental data in the ductile-to-brittle transition (DBT) region requires statistical methods for engineering design when using ferritic steels at sub-zero temperatures. The data-driven 2SS (two-step-scaling) method has been proposed recently to tackle the closely-related scatter and size effects in the DBT region. The present study introduces a further upgrade of the 2SS technique developed to include a predetermined level of conservatism tailored to specific applications. This controlled level of conservatism is incorporated in the 3-parameter Weibull 2SS procedure by prescribing a single multiplier χ ≤ 1. The practical application of this conservative version of 2SS technique is demonstrated using the EURO fracture toughness dataset for 22NiMoCr37 reactor steel. The KJc experimental data is utilized to assess the accuracy of predictions of the KJc cumulative distribution function achieved through extrapolation for the specified χ values
Immobilization of chemically modified glucose-oxidase by biomineralization in ZIF-8
No full textPrevious works showed that the characteristics of biomineralized enzymes can be improved by
periodate oxidation.1,2 Furthermore, functional groups such as histidine and aspartate that can interact
with zinc and 2-methylimidazole could significantly influence the process of biomineralization and
maybe increase the specific activity and stability of biocomposites. In this work, we have optimized
the reaction conditions, such as the concentration of zinc and 2-methylimidazole, and determined
that the best results are obtained with the lowest concentrations of zinc and 2-methylimidazole. Also,
we have shown that by introducing new functional groups within the enzyme molecule, especially
histidine vs aspartate, the specific activity of the biocomposite is twice as high compared to the
native enzyme due to the presence of coordinative bonds. The biocomposites synthesized in this way
also showed very high stability towards detergents like sodium dodecyl sulfate, which indicates that
the enzyme is immobilized inside ZIF-8