Determination Of Surface Area Research Articles

UoC‐2: A Fluorinated Derivative of the Robust Metal‐Organic Framework MFM‐300

By solvothermal reactions of fluoro substituted biphenyl‐3,3’,5,5’‐tetracarboxylic acids (H4BPTC) with the respective metal salts, four new MOFs with the MFM‐300 topology were synthesized, namely [MIII2(OH)2(L)] with MIII = Ga3+, In3+ and L = 4‐mF‐BPTC4‐ and 4,4’‐dF‐BPTC4‐. Three of them were refined from X‐ray single crystal diffraction data (I4122, Z = 4), [Ga2(OH)2(4,4’‐dF‐BPTC)] was confirmed by Le Bail fits based on synchrotron powder diffraction data. To the best of our knowledge, these four compounds represent the very first examples of MFM‐300 type MOFs with a substituted BPTC4‐ linker. With increasing fluorination of the linker, the thermal stability decreases, as the decarboxylation of the linker is facilitated. On the other hand, the gas uptake is enhanced significantly. E.g. the CO2 uptake (273 K, 1 bar) increases from 124 cm3/g for [Ga2(OH)2(4‐mF‐BPTC)] to 136 cm3/g for [Ga2(OH)2(4,4’‐dF‐BPTC)]. Surprisingly, the exact determination of specific surface areas (SBET) turned out to be difficult. It is supposed that due to transient open metal sites, complete removal of solvent molecules (DMF, acetone) is not always possible before degradation of the framework starts.

A Novel Approach for Accurate Determination of Laminar Burning Velocity Using the Constant Volume Method in a Cylindrical Vessel with Full Optical Access

ABSTRACT The constant volume method (CVM) is a potential method for determining laminar burning velocity (LBV) at high pressures and temperatures. However, CVM using spherical vessels gives no optical access to the flame; in cylindrical vessels, with full optical access, the flame does not remain spherical. In either case, one has to rely on semi-analytical models, which have limitations in accuracy, to obtain burned gas volume (BGV) needed for LBV calculation. This study presents a novel approach for accurate determination of BGV and flame surface area (FSA) of non-spherical flames in cylindrical vessels from the measured end-view flame radius. Through CFD simulation, normalized relationships are developed to relate the measured flame end-view radius to the actual FSA and BGV. It is shown that these relationships are purely geometry-dependent and are independent of vessel size and combustion reactions in the vessel. This facilitates accurate determination of LBV using CVM in an optically accessible cylindrical vessel, eliminating the requirement to estimate burned gas mass fraction using burned gas mass fraction models. Experiments using CVM were performed for a stoichiometric methane-air mixture at 1.0 bar and 300 and 350 K. This new approach is demonstrated by using it to determine the LBV of stoichiometric methane-air mixture accurately. The present methodology is expected to provide a way to calculate accurate LBV without the need for additional thermodynamic models for burned gas mass fraction.

Thermodynamic Investigations for Combustion-Assisted Synthesis of Lithium Orthosilicate Powders

AbstractThe study investigates the combustion-assisted synthesis of lithium orthosilicate (Li4SiO4) powders for potential CO2 capture applications. Technical-grade lithium carbonate and metallic silicon powders were used as starting materials. Synthesis conditions were explored across temperatures ranging from 500 to 900 °C and different holding durations. Thermodynamic modeling using FactSage 8.2 software suggested that Li4SiO4 production is feasible at temperatures of 700 °C and higher with metallic silicon as the silicon source, which was confirmed experimentally. Characterization of the synthesized powders involved X-ray diffraction, specific surface area determination, particle size distribution analysis, scanning electron microscopy, and CO2 uptake tests. Despite having the lowest Li4SiO4 content as 83.7%, the sample synthesized at 700 °C with 45 min of holding time showed the best CO2 uptake performance as 12.80 wt% while having the lowest crystallite size value (126.58 nm), the highest specific surface area value (4.975 m2/g) and the lowest average particle size value (10.85 µm) which are highly effective on the CO2 uptake performance of such solid sorbents. The study concludes that while challenges remain in achieving optimal CO2 capture performance, it lays a foundation for utilizing lithium orthosilicate in carbon capture applications. Graphical Abstract

Role of porosity on silica immobilized palladium complexes as recyclable catalysts in the methoxycarbonylation of 1-hexene

Immobilization of the palladium complex [Pd(L1)Cl2] (Pd1), where L1 = N,N'E,N,N'E)-N,N'-(3-(3-(triethoxysilyl)propyl)pentane-2,4-diylidene)dianiline, on MCM-41 and SBA-15 supports at 100 °C and Pd loading of 10% afforded the respective materials [Pd1@MCM-41] (Pd2) and [Pd1@SBA15] (Pd3) in moderate yields. Calcination temperatures of 150 °C and 200 °C using SBA-15 support gave the corresponding compounds Pd4 and Pd5 respectively, while using MCM-41 support and Pd loadings of 5% afforded compound Pd6. The characterization of the new materials was achieved by using FT-IR for functional group analyses, ICP-OES, TEM and SEM-EDX and XPS for surface morphology, elemental composition, particle size distribution and oxidation status respectively, PXRD for crystallinity and N2 physisorption measurements for surface area and porosity determinations. All the immobilized materials (Pd2–Pd6) formed active catalysts in the methoxycarbonylation of 1-hexene with moderate catalytic activities (TON of 372) to afford mainly linear esters. The catalytic activities of the materials depended on the nature of support and their physical properties and was largely controlled by their porosity. The SBA-15 supported catalysts, which displayed larger pore sizes, were generally more active than those of supported on MCM-41. The supported catalysts were recycled five times with minimum reduction in catalytic activities.

Enhancing adsorption capacity of a kaolinite mineral through acid activation and manual blending with a 2:1 clay

The efficiencies of raw and modified kaolinite mineral in removing selected heavy metal ions from their respective aqueous solutions were investigated. The mineral was modified through two different methods; i) activation with HNO3, H2SO4, H3PO4, CH3COOH and C2H2O4 acids to form NK, SK, PK, AK and OK acid activated clays respectively and ii) preparations of 3:1 and 1:1 Kaolinite: Bentonite blends to form UBK and EBK composites respectively through manual blending. The adsorbents were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red Spectroscopy (FTIR) and Brunauer Emmett Teller (BET) analysis for surface area determination. The surface area increased in some of the modified clays from 114.9457 m2/g (RK) to 288.685 m2/g (EBK), 205.92 m2/g (UBK), 162.227 m2/g (NK), 151.335 m2/g (SK), and 115.837 m2/g (OK) but reduced to 113.872 m2/g (PK) and 112.865 m2/g (AK) after modification. Adsorption studies were subsequently conducted out to remove Pb2+, Cd2+ and Ni2+ ions from synthetic solutions. Pb2+ was found to be most removed (383.5 mg g-1 (RK), 591.13 mg g-1 (EBK), 576.61 mg g-1 (UBK), 475 mg g-1 (NK), 450 mg g-1 (SK), and 425 mg g-1 (PK), 375 mg g-1 (OK) and 375 mg g-1 (AK)) with highest removals on the composites.

Synthesized MgFe<sub>2</sub>O<sub>4</sub> nanoparticles to remove Pb<sup>2+</sup> from aqueous solution

In the present paper, nanosized magnesium ferrite (MgFe2O4) material is synthesized by the hydrothermal method. The size and microstructure of magnesium ferrite were analyzed based on X-ray diffraction (XRD), scanning electron microscopy (SEM). The nitrogen adsorption-desorption was used for determination of surface area (Brunauer – Emmett – Teller (BET)) and porosity of the fabricated material. The adsorption behavior of Pb2+ using a new magnetic adsorbent is investigated. The adsorption characteristic and Pb2+ removal efficiency of the adsorbent have been determined by investigating the influence of operating variables such as dosage of manganese ferrite. The maximum Pb2+ sorption capacity was found to be 16,08 (mg/g) and obtained using 0,1 g/L MgFe2O4 when pH equals 5, a temperature of 25 °C, and contact time as 24 h. The Langmuir and Freundlich models were used to fit the experimental data and these showed good correlations.

Non-destructive chromatographic determination of surface area in reverse phase chromatographic columns

One of the critical but underutilized parameters that affect chromatographic separation is an adsorbent surface area (S.A.). We introduce a concept of direct determination of the total surface area of chromatographic columns by utilizing a nondestructive measurement of eluent component excess adsorption isotherm measurement and the application of the Standard Excess Adsorption Isotherm from acetonitrile-water and methanol-water binary mixtures for direct determination of the S.A. in chromatographic columns. This nondestructive technique was used to determine the surface area of five commercial columns, including three core-shell particle type columns (Kinetex-C18, Ascentis C18, and Hallo C18) and in-housemade C18 columns. The traditional low-temperature nitrogen adsorption (LTNA) technique was compared to the novel chromatographic method of nondestructive surface area determination for adsorbents modified with octadecylsilanes. The chromatographically determined surface area was in good agreement with the conventional techniques for all columns used. The difference between the three techniques is less than 10%. Columns were characterized in terms of adsorbent geometry (e.g., pore volume, column void volume, interparticle volume), ligands bonding density, and the amount of the packing material in a chromatographic column.

ANALYSIS OF THE POSSIBILITY OF USING MEDICAL CLAYS TO OBTAIN SORPTION DOSAGE FORMS

Introduction. Currently, medical clays in Russia are represented by the drug "Smectite dioctahedral", which accounts for 25% of all enterosorbents. Compared to 2014, the share of medical clays in the total structure of enterosorbents has increased fourfold. The search for new sources of medicinal mineral raw materials for the production of sorption dosage forms is an urgent task of pharmaceutical technology. The purpose of the work is to analysis of the possibility of using medical clays to obtain sorption dosage forms. Material and methods. Two medical clays were selected as objects of research: sample "X" – clinoptilolite clay of the Kholinsky deposit (Russia, Trans-Baikal Territory), sample "I" – zeolite clay of the Western Aftar deposit (Iran). The determination of the specific surface area and porosity was carried out by low-temperature nitrogen sorption on a TriStar II 3020 analyzer, microscopy was carried out on an electron–ion scanning microscope FEI Quanta 600 FEG. Results. A comparative analysis of technological and adsorption characteristics of clays was carried out. It was found that the clinoptilolite clay of the Kholinsky deposit is symmetrical equiaxed particles in the form of spherical formations, the average particle size is 6.33 microns, the specific surface area is 20.9227 m2/g, the pore volume is 0.058435 cm3/g, the average pore size is 11 nm, has mesopores (17-50 nm) and macropores. A study of the morphological characteristics of the zeolite clay of the Western Aftar deposit (Iran) shows that the clay consists of agglomerates of irregularly shaped particles with an average size of 2.00 microns. According to the obtained adsorption characteristics, clay has a specific surface area of 20.4654 m2/g, a pore volume of 0.065848 cm3/g, an average pore size of 13 nm, has mesopores (18-50 nm) and macropores. Conclusions. The studied clays are mesomacroporous sorbents with a predominance of mesopores. Satisfactory adsorption indicators show the pro-spects of using medical clays to obtain sorption dosage forms.

Particulate iron oxide food colorants (E 172) during artificial digestion and their uptake and impact on intestinal cells

Iron oxide of various structures is frequently used as food colorant (E 172). The spectrum of colors ranges from yellow over orange, red, and brown to black, depending on the chemical structure of the material. E 172 is mostly sold as solid powder. Recent studies have demonstrated the presence of nanoscaled particles in E 172 samples, often to a very high extent. This makes it necessary to investigate the fate of these particles after oral uptake. In this study, 7 differently structured commercially available E 172 food colorants (2 x Yellow FeO(OH), 2 x Red Fe2O3, 1 x Orange Fe2O3 + FeO(OH) and 2 x Black Fe3O4) were investigated for particle dissolution, ion release, cellular uptake, crossing of the intestinal barrier and toxicological impact on intestinal cells. Dissolution was analyzed in water, cell culture medium and artificial digestion fluids. Small-angle X-ray scattering (SAXS) was employed for determination of the specific surface area of the colorants in the digestion fluids. Cellular uptake, transport and toxicological effects were studied using human differentiated Caco-2 cells as an in vitro model of the intestinal barrier. For all materials, a strong interaction with the intestinal cells was observed, albeit there was only a limited dissolution, and no toxic in vitro effects on human cells were recorded.

Improved Soil Amendment by Integrating Metal Complexes and Biodegradable Complexing Agents in Superabsorbents.

The superabsorbents' application as materials for the preparation of modern mineral fertilizers of controlled activity is presented. Under the static conditions, the commercial acrylic-based Agro® Hydrogel was used as a sorbent for Cu(II), Fe(III), Mn(II), and Zn(II) ions in the presence of three biodegradable complexing agents of the new generation: (N-1,2-dicarboxyethyl)-D,L-aspartate acid (IDHA), N,N-ethylenediaminedisuccinic acid (EDDS) and N,N-bis(carboxymethyl) glutamic acid (GLDA). The ions and complexes concentrations were determined by the inductively coupled plasma optical emission spectrometer (ICP-OES). The characterization of hydrogel before and after the adsorption process was made using the Fourier transform infrared spectroscopy (FT-IR), surface area determination (ASAP), scanning electron microscopy (SEM-EDS) as well as the thermogravimetric (TGA) methods. The influence of the phase contact time, initial concentration, and pH on the adsorption capacities was investigated. The kinetic and adsorption parameters were determined. The Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin adsorption models were applied to describe the experimental data. The Langmuir isotherm model accurately characterized the equilibrium process. The adsorption process was fast, and it reached equilibrium after 60 min of the phase contact time. The research on the adsorption of Cu(II), Fe(III), Mn(II), and Zn(II) onto Agro® Hydrogel with IDHA, EDDS, and GLDA indicates that these complexing agents improve process efficiency.

Adsorptive removal of biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) from greywater using activated carbon prepared from tropical almond and palm kernel shells

This study assesses the reduction of 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) of household greywater using palm kernel activated carbon (PKAC) and tropical almond activated carbon (TAAC) produced from locally available materials in a kiln at 800oC and activated using steam at a flowrate of 120 mL hr-1. Brunauer-Emmet-Teller (BET) surface area determination revealed that PKAC had a larger surface area than TAAC. Scanning electron microscope (SEM) imagery of the carbons also revealed amorphous and large internal shapes for TAAC while crystalline and closed packed shapes for PKAC. X-ray diffraction (XRD) analysis indicated that the major component present in the PKAC and TAAC was carbon and other allotropes of carbon. Batch results showed that reduction of BOD5 and COD was affected by particle size. The maximum percentage reduction of BOD5 and COD by PKAC was 76% and 65% respectively while reduction by TAAC was 62% and 52% respectively. The adsorption process was well described by the Freundlich adsorption isotherm. The studies showed that PKAC is a better adsorbent for reducing BOD5 and COD from domestic greywater as compared with TAAC. The PKAC is a potential low-cost adsorbent for BOD5 and COD removal from domestic greywater.

Experimental Challenges in the Electrocatalytic Benchmarking of Multicomponent Alloys

Multicomponent alloys, especially complex solid solutions (CSS), and more specifically high entropy alloys (HEA) have emerged as promising new types of electrocatalysts [1] for numerous reactions of significance for energy conversion. Their exceptional properties and the large number of degrees of freedom available for tuning their properties make CSSs promising candidates for overcoming the limitations of traditional catalysts: activity limitations imposed by the scaling, as well as stability issues.Despite the large interest they have garnered, their potential still remains to be understood and harnessed, as their electrochemical behavior still needs to be understood. Significant experimental challenges need to be addressed and widely applied standards need to be implemented in order to understand and correctly asses the electrocatalytic behavior of such catalysts. The electrochemical surface area (ECSA) determination, identification of active sites, understanding their operando behavior, effects of crystallinity [2] as well as basic experimental challenges, such as careful Ohmic drop correction, are some of the most important experimental challenges in the electrocatalytic assessment of CSSs.Here, an overview of CSS catalysts for the oxygen reduction reaction to date will be given (Figure 1A) [1]. Traditional methods used to evaluate the ECSA of well-known systems (e.g. noble metal electrodes) are discussed in relation to their use in CSS evaluation. For instance, the application of double layer charging current techniques, surface limited reactions and surface science techniques all have their advantages and drawbacks for the determination of the electrochemical surface area in terms of ease of application, size of errors introduced and reliability. Additionally, crystallinity (more generally, the effects of long- and short-range order, Figure 1B), phase separations, oxide layer growth and other caveats during electrocatalytic benchmarking of CSSs will be discussed. Figure 1

Effect of Electrochemical Surface Oxidation on Intrinsic Activity Towards the Hydrogen Evolution Reaction of Ultra-Smooth Nanocrystalline Ni Thin Films

Green hydrogen has emerged as a leading contender in the pursuit of a sustainable energy transition, driving the need for optimized catalysts in hydrogen production. Therefore, considerable effort is taken to replace the highly active, yet expensive Pt-group metals with non-noble alternatives such as Ni. Understanding the hydrogen evolution reaction (HER) mechanism on well-performing Ni surfaces is essential for gaining fundamental knowledge and implementing this in practical applications. While high surface area structures are typically designed for enhanced efficiency, there is limited research available on the fundamental aspects of thin films and smooth surfaces, which are crucial for benchmarking intrinsic catalytic activity and elucidating catalytic mechanisms. To address this gap, we perform a combined microstructural and electrochemical evaluation of smooth Ni thin film electrodes to analyze HER in alkaline media.This study aimed to evaluate the intrinsic catalytic properties of nanocrystalline Ni thin films and the effect of electrochemical oxidation on the catalytic behavior, while precisely monitoring the evolution of the film surface state and roughness. In addition to experimental work, Density Functional Theory (DFT) calculations and Kinetic Monte Carlo (KMC) simulations are used to understand HER on oxide-modified Ni surfaces and the role of different elementary processes involved in the HER mechanism.Nanocrystalline low-roughness Ni electrodes for HER were produced via magnetron sputter deposition to minimize the difference between geometrical and electrochemical surface area. This means we find intrinsic material properties directly, bypassing the need for additional measurements for real surface area determination. The analysis of catalyst activities towards HER as well as the oxidation process [1] was performed via cyclic voltammetry, using a three-electrode setup. Within the conducted studies, we can report a significant lowering of the overpotential for HER upon in-situ oxidation of the electrodes due to the existence of NiO, and Ni(OH)2 on the Ni catalyst surface [2], leading also to a limitation of the deactivation processes. Further analysis including topography evaluation (AFM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) in combination with selected area diffraction (SAED) of the as-deposited and oxidized electrodes confirmed that the observed effect can be assigned to the availability of oxides on the surface assuredly (Figure 1). Additionally, theoretical calculations and simulations (DFT, KMC) support the experimental data and derived theories.In conclusion, the beneficial effect of NiO and Ni(OH)2 presence on Ni surfaces was examined and successfully proven by a combination of electrochemical measurements, material characterization, theoretical calculations, and a careful experimental design that minimizes the influence of interfering factors, such as surface roughness.

The determination of the electrochemically active surface area and its effects on the electrocatalytic properties of structured nickel electrodes produced by additive manufacturing

Additively manufactured (AM) nickel electrodes offer a great potential as an efficient solution for oxygen evolution catalysts in alkaline electrolyzers, since advanced fabrication methods allow the design of high surface area electrodes. The accurate determination of the electrochemical active surface area (ECSA) is a key step in the evaluation of the intrinsic catalytic activity of complex electrodes. In this work, we fabricated Ni electrodes with different macroscopic lattice structures using laser powder bed fusion of metals (PBF-LB/M). The selected designs allow exploring the effects of the electrode geometry on the electrochemical performance. X-ray photon spectroscopy (XPS) and a non-contact optical profilometer (NCOP) were used to investigate the composition and surface morphology of the electrodes. The ECSA was determined by three different approaches. 1. Linear and non-linear allometric fitting of the double layer capacitance from voltammetric experiments. 2. Integration of the Ni2+/Ni3+ transition, also from voltammetry. 3. Assessing double layer capacitance determined from electrochemical impedance spectroscopy (EIS) at open circuit potential (OCP) and the adsorption capacitance for the oxygen evolution reaction (OER) intermediates. Comparing these methods, large deviations in the resulting ECSAs were found, motivating a comprehensive discussion. In addition, four different reactions were investigated, ferri-ferrocyanide redox system, hydrogen evolution, ethanol electrooxidation, and oxygen evolution reaction. The obtained results demonstrate the potential of AM to tailor electrode performance by altering electrode geometry. The findings underline the importance of the ECSA determination for the comparison of the electrocatalytic activity in different electrodes.

Robinia pseudoacacia L. (Black Locust) Leaflets as Biomonitors of Airborne Microplastics.

Here we investigate the suitability of Robinia pseudoacacia L. (black locust) leaflets as a novel biomonitor of airborne microplastics (MPs) including tyre wear particles (TWPs). Leaflets were collected from rural roadside locations (ROs, n = 5) and urban parks (UPs, n = 5) in Siena, Italy. MPs were removed by washing, identified by stereomicroscope, and analysed for polymer type by Fourier transform infrared spectroscopy. Daily MP deposition was estimated from leaf area. The mass magnetic susceptibility and the bioaccumulation of traffic-related potentially toxic elements (PTEs) were also analysed. The total number of MPs at ROs was significantly higher at 2962, dominated by TWPs, compared with 193 in UPs, where TWPs were not found. In contrast, total microfibres were significantly higher in UPs compared with ROs (185 vs. 86). Daily MP deposition was estimated to range from 4.2 to 5.1 MPs/m2/d across UPs and 29.9-457.6 MPs/m2/d across ROs. The polymer types at ROs were dominated by rubber (80%) from TWPs, followed by 15% polyamide (PA) and 5% polysulfone (PES), while in UPs the proportion of PES (44%) was higher than PA (22%) and polyacrylonitrile (11%). The mean mass magnetic susceptibility, a proxy of the bioaccumulation of traffic-related metallic particles, was higher at ROs (0.62 ± 0.01 10-8 m3/kg) than at UPs (-0.50 ± 0.03 10-8 m3/kg). The content of PTEs was similar across sites, except for significantly higher concentrations of Sb, a tracer of vehicle brake wear, at ROs (0.308 ± 0.008 µg/g) compared with UPs (0.054 ± 0.006 µg/g). Our results suggest that the waxy leaflets and easy determination of surface area make Robinia an effective biomonitor for airborne MPs including TWPs.

Application of a novel zirconium coagulant in the coagulation-ultrafiltration process: Fluoride removal and membrane fouling alleviation

Groundwater fluoride pollution is a worldwide problem that threatens human health and drinking water. Economical and efficient coagulation is the most widely used defluorination technology. The fluoride removal efficiency depends on the complexation and adsorption capacities of the hydrolyzed metal salt coagulant, so the development of new metal coagulants is the key to coagulation defluorination technology. In this study, novel polymeric zirconium salt coagulants (ZXCs) were prepared by the sol-gel method. Their capabilities in coagulation and coagulation-ultrafiltration processes were evaluated and compared with those of the traditional polyaluminum chloride (PAC) and polyferric sulfate (PFS) coagulants. ZXC exhibited more effective fluoride removal than PAC and PFS, and the fluoride removal rates of ZXC, PAC and PFS were 81.0 %, 24.7 % and 5.4 % with the optimized dosages of 0.30 mM and pHs of 5.0, 6.0 and 5.0, respectively. With an initial fluoride concentration of 4.0 mg/L, 0.30 and 1.5 mM doses of ZXC reduced the fluoride concentrations to 0.76 and 0.13 mg/L. The structures and properties of ZXC and the flocs were characterized with Fourier Transform Infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), X-ray photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area determinations. The series characterization and hydrolysis precipitation area map showed that adsorption onto hydroxyl groups and ion exchange with surface hydroxyl groups were the main pathways for fluoride removal by ZXC. In the coagulation-ultrafiltration defluorination process, the highly polymerized ZXC was fully hydrolyzed under acidic conditions to form larger and looser flocs with almost no dissolved residue, which substantially reduced membrane fouling. This work provides new insights into the development of materials and technologies for fluoride removal from drinking water.

“Adsorptive removal of Congo Red dye from its aqueous solution by Ag–Cu–CeO2 nanocomposites: Adsorption kinetics, isotherms, and thermodynamics”

Eliminating synthetic dyes and organic contaminants from water is crucial for safeguarding human health and preserving the environment. In this study, we explored the effectiveness of Ag–Cu–CeO2 nanocomposites as adsorbents to remove Congo Red dye from water. Three compositions of Ag–Cu–CeO2 nanocomposites (10:20:70, 15:15:70, and 20:10:70) have been synthesized by the aqueous coprecipitation method. A comprehensive analysis was performed by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, BET surface area determination, Thermogravimetric analysis, Scanning electron microscopy, and TEM. The synthesized nanocomposites have a dimension of 5 ± 1 nm and a high surface area (51.832–78.361 m2g-1).Among these, the nanocomposite with composition 15:15:70 showed the highest adsorption capacity of 4.71 mg/g adsorption (96.83 % removal) from the 0.8 × 10−4 M (55.6 mg/l) Congo Red solution at pH values of 2 at 20 °C with contact time of 3h. The adsorption data is best fitted in the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The negative values of enthalpy variation (−27.57, −26.43, and −16.73 kJ/mol) demonstrated that the adsorption was spontaneous and exothermic. The cycling run showed a mere 12 % deactivation after five cycles of use thus indicating that Ag–Cu–CeO2 nanocomposites hold great potential as effective and eco-friendly adsorbents to remove Congo Red from water.

Enhanced hydrogen generation in low-range acidic solutions using Mg2NiH4 powders and their mixtures ball-milled with NaCl and fused silica

Hydrogen production through hydrolysis shows a promise as a green and sustainable energy source that can be used for urgent need of energy on-board. This study presents a novel approach to boost the speed of hydrolysis reactions by utilizing Mg2NiH4 powder. The approach involves ball milling with NaCl and fused silica additives, that open additional active areas and accelerate the hydrolysis process. A comprehensive analysis encompasses morphology, elemental mapping, chemical bonding, structural changes, and surface area determination of the prepared powders. The hydrolysis reactions is performed using acetic acid solutions with different molarities (0.25 M, 0.12 M, and 0.06 M), as well as tap water. The impact on kinetics is profound, with reaction rates varying between 600 and 3000 ml/min during the initial seconds for different powders. Moreover, the study examines the application of such hydrolysis system for electricity generation through a proton-exchange membrane fuel cell.

A comparative study on thermochemical decomposition of lignocellulosic materials for energy recovery from waste: Monitoring of evolved gases, thermogravimetric, kinetic and surface analyses of produced chars

Increased waste generation caused by the growth of urbanisation rate forces scientists and policymakers to rapidly develop and implement optimal waste management strategies. Since there are many ways to waste treatment and each waste material has different physicochemical properties, they should be investigated separately. This paper presents the results of an experimental investigation on the thermal decomposition of the spent coffee grounds (SCG) and textiles under various atmospheres using a vertical tube furnace. In the study, different analytical techniques are used, such as gas chromatography (GC), gas adsorption for surface area and porosity determination, Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Results indicated that SCG sample yielded more calorific pyrolytic gas (209.8 kJ/mol). than TEX (198.7 kJ/mol). O2/CO2 atmosphere fasten the fuel decomposition. Concerning biochar, it can be concluded that fast pyrolysis influenced their combustion performance, for example, its ignition temperature, TEX_slow (475.4 °C) > SGS_slow (470.5 °C) and TEX_fast (469.6 °C) > SGS_fast (415.0 °C), maximum weight loss rates and reactivity. This study will provide a better understanding of thermochemical degradation of waste and allows for developing optimal routes of waste utilisation.

Efficiency of the compensatory scheme of using Organic Acid Nano-Complex microfertilizers in spring wheat cultivation technology

In recent years, significant advances in nanotechnology have increased the ability to produce nanoparticles of physiologically important metals on a large scale, which are now used to improve fertilizer formulations to increase uptake by plant cells and minimize nutrient losses. Fertilizers with nanostructure can increase the efficiency of nutrient use through mechanisms such as targeted delivery, slow or controlled release. The aim of the research is to substantiate a compensatory scheme for the use of biodynamic nanofertilizers (nanocomplex micronutrient fertilizers with organic acids) by partially replacing the main macrofertilizers in the spring wheat fertilization system. The research was conducted on the basis of the educational and scientific laboratory Department of Plant Industry of the National University of Life and Environmental Sciences of Ukraine. In research, there were used the methods of field experiments of A.O. Rozhkov, notching method and scanning method for determination of leaf surface area. The studies showed that it is possible to replace within 30-40% of the recommended amount of mineral fertilizers with biodynamic nanofertilizers in the spring wheat fertilization system. In general, the use of nanofertilizers increased wheat growth and improved yield and yield components. Substitution of mineral fertilizers, Innoparmis Agroscience Biodynamic fertilizers, provides a more favourable 86-88% survival rate of spring wheat plants during the growing season. By replacing 34% of the recommended rate of mineral fertilizers, the content of photosynthetic pigments in wheat leaves increases by 5% and the leaf surface area increases by 7%. The created compensatory schemes for the use of biodynamic nanofertilizers by partial (34% in the wheat fertilization system) replacement of the main macronutrients can increase the yield of spring wheat by 9.9%. The proven possibility of replacing mineral fertilizers with biodynamic nanofertilizers in the fertilization system of agricultural crops will reduce environmental pollution and the economic dependency of using mineral fertilizers against the background of their rapid increase in price in recent years