Release Of Elements Research Articles

Preparation and characterization of a CDs based hydrogel slow-release fertilizer

Low utilization rate of chemical fertilizers is a main limitation for improving crop yields. Peanut bran carbon dots (CDs) have been shown to boost Italian lettuce growth, while hydrophilic CDs can easily flow away with water during application, which leads to CDs wastage and water losing. Therefore, it is crucial to develop a material with slow-release capacity of nutrient elements and CDs along with water-retaining function. In this study, acrylic acid and acrylamide were reacted with urea, potassium phosphate and other materials, thus a hydrogel slow-release fertilizer was firstly designed. Then, peanut bran CDs were added into the hydrogels to prepare a novel CDs based hydrogel slow-release fertilizer (CDs-hydrogels). Experimental results show that the prepared CDs-hydrogels have high water retention capacity and element release capacity of N, P, K. Most importantly, the CDs within these hydrogels, via its changes in luminescence, the releasing rate of nutrient elements can be monitored.

Molecular mechanisms of phosphorus immobilization by nano-clay mediated by dissolved organic matter

The adsorption of phosphorus (P) by minerals, particularly clay minerals, plays a crucial role in the biogeochemical cycling of P in geological environments such as soil and groundwater. However, the mechanisms underlying the immobilization and subsequent release of element P by nano-clay are still not well comprehended. This study delves into the mechanism of adsorption of inorganic phosphate and organic phytate onto laponite, serving as a representative nano-clay. This aspect has frequently been disregarded due to research method limitations; nevertheless, the substantial specific surface areas (SSA) are abundant in a multitude of potential adsorption sites. Batch experiments were conducted to evaluate surface reaction and adsorption capacity under varying solution conditions, including pH, ionic strength, and the presence of dissolved organic matter (DOM). The results demonstrate that the adsorption capacity of laponite decreases with increasing pH. Additionally, the adsorption capacity initially increases within the range of 10–50 mM NaCl and then decreases within 50–100 mM NaCl, while the presence of DOM significantly inhibits P adsorption. Complementary techniques such as X-ray photoelectron spectroscopy (XPS), zeta potential analysis, atomic force microscopy (AFM) were employed to gain further insights into the adsorption process. These analyses revealed that DOM obstructs P adsorption by occupying adsorption sites and promoting the aggregation of laponite nanoparticles. Furthermore, AFM-based dynamic force spectroscopy (DFS) provides molecular-scale thermodynamic support for the observed P adsorption phenomena on laponite under different conditions. The findings of this study contribute to a better understanding of the P adsorption mechanism of nano-clay and have valuable implications for the biogeochemical cycling of P in soil and groundwater.

Temperature resolved release of inorganic compounds from biomass

The release of inorganic compounds during the thermal conversion of solid biomass can cause severe operational problems in thermal power plants. To effectively reduce fine particle emissions and depositions, it is important to understand the release of problematic elements into the gas phase.This study presents a temperature-resolved analysis of the release of potassium, sodium, chlorine, sulfur, phosphorus, calcium, and magnesium from ten biomass samples. Conventional woody biofuels, alternative woody biofuels, and stalk-like biomass are analyzed in an electrothermal vaporization unit (ETV) which is connected directly to an inductively coupled plasma optical emission spectrometer (ICP-OES). The suppression of secondary gas-phase reactions in the given setup enables the isolated observation of each individual species’ release pattern. The results from this experimental setup are compared to a range of release patterns found in the literature, with a particular focus on potassium. For the high heating rates applied in this setup, the potassium release starts at around 700 °C, with the majority being release between 1000 °C and 1400 °C. Since hardly any potassium is released together with chlorine and sulfur, the majority of it is released as KOH or elemental potassium. Overall, this work presents reproducible temperature-resolved release patterns of inorganic elements from various biogenic feedstocks in an inert atmosphere.

Chemical durability of multicomponent lanthanide zirconate solid solutions

Multicomponent zirconate solid solutions A2Zr2O7 (A= (Sm,Yb), (Sm,Yb,Gd), (Sm,Yb,Gd,Er), and (Sm,Yb,Gd,Er,Dy)) were synthesized through spark plasma sintering and their chemical durability was investigated via semi-dynamic leaching tests in pH = 1 nitric acid at 90 °C. Incongruent dissolution occurred for all samples with the preferential elemental release of zirconium in all A2Zr2O7 except for high entropy (Sm,Yb,Gd,Er,Dy)Zr2O7 which displays a congruent release of the A-site elements and Zr. A strong positive correlation was found between the lanthanide elemental release rates and the A-site cation size disorder, whereas a negative correlation was observed between the elemental release rates and mixing entropy.

Chemical durability and corrosion-induced microstructure evolution of compositionally complex titanate pyrochlore waste forms with uranium incorporation

Chemical durability of compositionally-complex rare-earth titanate pyrochlore solid solutions with or without uranium incorporation was investigated by semi-dynamic leaching testing. A Ti-enriched amorphous passivation film formed on the surface due to the surface alteration-reorganization mechanism with preferential release of the weakly oxygen-bonded rare earth elements. Elemental release was found to be strongly correlated with chemical disorder, with a negligible correlation with entropy. The release rate of the uranium gradually decreased with increasing numbers of components, implying a possibility of designing and optimizing waste form performance with enhanced chemical durability by controlling composition complexity and chemical disorder for effective nuclear waste management.

Strengthening Mechanisms of Ti–Mg Composite for Biomaterials: A Review

Titanium (Ti) has been widely used in biomedical implants due to its excellent mechanical properties and biocompatibility. However, the “stress shielding” effect greatly limits the application of titanium alloys in medical devices. Studies have shown that the incorporation of bioactive elements into the titanium alloy matrix is an effective way to impart specific biological functions to the material through the sustained release of biofunctional elements. Magnesium (Mg) and its alloys have good bioactivity and are potential candidates for biodegradable metal implants. Ti–Mg composites are of increasing interest for biomedical applications. However, the incompatibility between Ti and Mg, such as immiscibility and large melting point difference, has been a great obstacle in preparing Ti–Mg composites. In addition, the biocompatibility of Ti–Mg metal matrix composites in vivo still needs to be further investigated. Herein, the recent research progress of Ti–Mg composites for biomedical implants is reviewed, focusing on their preparation methods and properties. The preparation methods such as powder metallurgy technology and 3D printing are introduced in detail. In addition, the mechanical and corrosion resistance as well as biocompatibility of Ti–Mg composites are discussed. Based on this, the problems and development prospects of Ti–Mg metal matrix composites are presented.

Experimental determination of the reactivity of basalts as a function of their degree of alteration

The element release rates from naturally altered basalts were measured in batch experiments at 27 °C, and in mixed-flow experiments at 25 °C in reactive fluids initially consisting of pH 3 or 4 aqueous solutions. The basalts reacted in this study consist of 1) surface weathered basalts ranging in age up to 13 million years, and 2) hydrothermally altered basalts from zeolite to actinolite alteration zones (temperatures of ∼50 to 300 °C). The in situ pH in the batch experiments increased over time with the final pH of the fluids ranging from to 4 to 8. Most experiments exhibited a preferential release of Ca and Mg compared to Si from the dissolving basalts, both initially and over the long-term. This behavior is attributed to the combination of an initial rapid cation-proton exchange reaction and the relatively fast dissolution rates of Ca-bearing minerals. The BET surface area normalized Si release rates for all of the altered basalts are within one order of magnitude of each other, and from one to two orders of magnitude lower than corresponding rates from fresh basaltic glass and fresh crystalline basalts. This is interpreted to stem from 1) the fast removal of reactive basaltic glass and olivine from fresh basalts during the natural alteration of the rocks, 2) the similarity of the dissolution rates of the remaining albitic plagioclase, pyroxenes, epidote, and zeolites, and 3) the high surface areas of some less reactive secondary minerals such as clays. Overall, the results suggest that altered basalts will be effective in consuming CO2 during both natural and engineered processes, though at a somewhat slower rate than unaltered basalts.

Study of the Effect of Biochar Incubation on Some Physico-Chemical Properties of a Tropical Leached Soil from South-West Chad

Soils in the Sudanian zone of Chad, and more specifically leached tropical soils, were subject to physical and chemical degradation phenomena that hamper crop production. Solving this problem requires solutions for the rational improvement of fertility. The aim of this study, conducted in a controlled environment, was to assess the fertilising potential of biochar on impoverished soil by monitoring the kinetics of the evolution and release of chemical elements that improve the physico-chemical quality of the soil. Four treatments were carried out: control soil (T0), treatment 1B: 100g soil + 0.225g biochar (i.e. 5 t/ha), treatment 2B: 100g soil + 0.3375g biochar (i.e. 7.5 t/ha) and treatment 3B: 100g soil + 0.450g biochar (i.e. 10 t/ha). Each treatment was repeated four times. Four main parameters were measured during the trial period: pH, assimilable phosphorus, exchangeable bases and their sums (Ca, Mg, K, Na and SBE) and cation exchange capacity. These different parameters showed that the biochar treatments significantly improved soil quality, whatever the dose and incubation time, compared with the T0 control. Treatment 1B (5t/ha biochar application) increased pH by an average of 6.5%, phosphorus by 132.5%, SBE by 406.1% and CEC by 43.4%. Treatment 2B (application of 7.5 t/ha of biochar) improved pH by an average of 8.5%, phosphorus by 155.1%, SBE by 207.6% and CEC by 46.2%. Treatment 3B (application of 10t/ha of biochar) produced a marked improvement, increasing pH by 11.2%, phosphorus by 198.7%, SBE by 457.6% and CEC by 29.9%. These results further confirm the vital importance of biochar in fertilising impoverished tropical soils. Based on pH, sum of bases and phosphorus, treatment 3B gave better results by considerably increasing the initial chemical element content of the control soil than the other biochar treatments.

ENVIRONMENTAL GEOCHEMICAL INVESTIGATION OF THE GEOGENIC POLLUTION POTENTIAL OF BIDA FORMATION, NORTHERN BIDA BASIN NIGERIA

The environmental geochemistry of sandstones of Bida formation around Doko, northern Bida Basin Nigeria was studied to assess the potential for the release of toxic elements into the environment. Eight representative samples were collected and analysed to determine the total elemental concentration using X-ray fluorescence spectrometry (XRF). Four sub-samples were analysed for their near-total concentration of selected metals using atomic absorption spectrometry (AAS). The results show that many of the elements are depleted with mean enrichment ratios of less than 1. Ce, W, Nb and Pb are the exceptions with ER values of 116.4, 122.9, 25.26 and 2.22 respectively. A similar pattern was found with Igeo, where W, Ce and Nb fall within strongly to extremely polluted and extremely polluted classes. High to very high partition coefficients (KDi) for four selected PTEs show that metals are strongly held within the sandstone matrix rather than dissolving. Because the elements are not soluble, they will not be readily available for uptake by plant roots, or will not be directly toxic to soil biota. The undissolved metal pool also reflects the sandstone metal fraction that is unsusceptible to leaching and could therefore not contaminate water. We conclude that there is no significant geogenic pollution risk associated with PTE release and uptake from the formation. It is however recommended that further research should be carried out to investigate the phases hosting Ce, W, Nb and Zr in the sandstone in Doko and its environs.

Thymol abates the detrimental impacts of imidacloprid on rat brains by lessening oxidative damage and apoptotic and inflammatory reactions

Imidacloprid (IMID) is one of the most widely used neonicotinoid insecticides globally and, consequently, a probable widespread environmental contaminant. The potential neurotoxic effects of IMID have been previously reported. This study aimed to investigate the possible beneficial effect of thymol (TML) in relieving IMID-induced harmful effects on the brain of male Sprague-Dawley rats. For this aim, four groups (10 rats/group) were orally administered corn oil, TML (30 mg/kg b.wt), IMID (22.5 mg/kg b.wt), or TML + IMID for 56 days. The brain tissues were biochemically, histopathologically, and immunohistochemically evaluated. The results displayed that TML significantly restored the IMID-induced depletion of the total antioxidant capacity of the brain tissues. At the same time, the IMID-associated increased levels of lipid peroxidation in terms of malondialdehyde content were markedly suppressed in the TML + IMID group. Also, TML oral dosing markedly reduced the release of inflammatory elements, including nitric oxide and myeloperoxidase, resulting from IMID exposure. Furthermore, the IMID-induced decrease in gamma-aminobutyric acid but the increase in acetylcholinesterase was considerably reversed by TML oral dosing. Additionally, TML oral administration significantly counteracted the IMID-induced brainepatic DNA damage, as revealed by the comet assay. Besides, a significant downregulatibrainepatic Caspase-3 was evident in the TML + IMID group compared to the IMID group. However, TML oral dosing has not significantly altered the IMID-induced nuclear factor (NF-κB p65) increase. Therefore, TML could be a protective agent against IMID-induced detrimental impacts on brain tissue, possibly through its antioxidant, antiapoptotic, and anti-inflammatory activities.

Forest floor and Na azide effect on elements in leachate from contrasting New Hampshire and Virginia forest soils

AbstractAs northeastern forests experience increased temperatures and fluctuations in precipitation patterns, montane soils will lose forest floor (Oi, Oe, Oa horizons) formation and their associated ecosystem services. Here, we conducted comparative laboratory soil column experiments to examine the effects of forest floor on sourcing and weathering of macroelements (Al, Si), macronutrients (Ca, Mg, P), and micronutrients (Cu and Zn) from two contrasting soils: a supraglacial‐till Inceptisol (Mt. Moosilauke, NH) and colluvium Ultisol (Lesesne State Forest, VA). Forest floor addition caused a significant increase in the leaching of Ca, Mg, and Mn in the two soils. The forest floor only control leachate indicates the two mineral soils were net accumulators of Al, Si, P, Cu, and Zn from the forest floor. Using partition coefficient, Kd, values, leachate Ca and Mg could be sourced directly from the forest floor traversing the soil column. We aimed to assess the biotic influence on element release from soil using a Na azide treatment to suppress microbial activities. Under Na azide treatments, Al, Ca, Mg, Mn, and Cu leachate decreased significantly for both soils, but Na azide also did not affect or increased leachate Si, P, Cu, and Zn for the Lesesne soil. We attribute the effects from Na azide to changes in pH, dissolved organic carbon, and oxidation‐reduction potential as opposed to suppression of microbes. Thus, our results suggest that the loss of the forest floor will reduce the storage of nutrients in the mineral soil, even across varying parent materials.

Heat treatments of 17-4 PH SS processed by SLM to improve its strength and biocompatibility in biomedical applications

This research investigates the impact of heat treatment on the microstructure, hardness, and corrosion resistance of 17-4 PH SS (stainless steel) processed by Selective Laser Manufacturing (SLM) in Phosphate Buffer Solution (PBS) and compared to its commercial wrought counterparts. The SLM process produced a segregated microstructure with significant variations in composition and phases. Post-process heat treatment resulted in a uniform and reproducible microstructure in the SLM samples with a significant improvement in corrosion resistance in the solubilised samples and a remarkable hardening in the solubilised and aged samples. Additionally, heat-treated SLM samples showed no relevant release of metallic elements to PBS electrolyte after 75 days of immersion, indicating its potential use as a biomaterial. The study concludes that the manufacturing process used to produce SS have a significant impact on its properties, moreover, post-build treatment improve microstructure providing uniformity which positively impact in the corrosion resistance. The electrochemical results also suggest that, after homogenization, the additively produced 17-4 PH SS shows a better behaviour in biological environment than the wrought 17-4 PH SS.

Ceramic materials based on lanthanum zirconate for the bone augmentation purposes: cytocompatibility in a cell culture model

Creation of new ceramic materials for the bone augmentation purposes that combine the absence of cytotoxicity, high strength and osseointegration characteristics is an urgent modern task. In this work, the cytocompatibility of ceramic materials based on lanthanum zirconate (La2Zr2O7) was determined to assess the prospects for their use as implants and components of human joint endoprostheses. The effect of ceramic materials based on undoped and alkali-earth (Ca, Sr) doped La2Zr2O7 on the viability and proliferative activity of human cells was evaluated. The release of elements into the culture medium was also evaluated.

Generation of a measurable magnetic field in a metal asteroid with a rubble-pile core

Paleomagnetic records of iron meteorites of the IVA group suggest that their parent body (an inward-solidified metal asteroid) possessed an internal magnetic field. The origin of this magnetism is enigmatic because inward solidification typically leads to light element release from the top of the liquid, which depresses convection and dynamo activity. Here, we propose a possible scenario to help resolve this paradox. The formation of a metal asteroid must involve a disruptive, mantle-stripping collision and the reaccretion of metal fragments. We hypothesize that a small portion of metal fragments may have substantially cooled before being reaccreted. These fragments could have formed a cold, rubble-pile inner core, which extracted heat from the liquid layer, leading to solidification and light element expulsion at the inner core boundary to power a dynamo. In the portions of the inward-growing crust that cooled below the remanence acquisition temperature, the magnetic field could be recorded.

Exploring the migration and transformation behaviors of heavy metals and ammonia nitrogen from electrolytic manganese residue to agricultural soils through column leaching test.

Heavy metals (HMs) and ammonia nitrogen (AN) leaching from electrolytic manganese residue (EMR) result in the contamination of agricultural soils and water bodies. Batch and column leaching tests were conducted to simulate the release of HMs and AN in EMR during precipitation, as well as their migration and transformation in agricultural soils. The results show that Mn, AN, Cd, Ni, and Zn present in the EMR had high acidsoluble fraction (un-fixed AN) content, and the leachability of Mn and AN was significantly higher than that of other hazardous elements. The cumulative release of hazardous elements in the EMR stockpile was well-fitted (R2 > 0.95) by the HILL model. Significant HMs and AN accumulated in the agricultural soils after contamination from the EMR leachate. The pollution degree of HMs in agricultural soils was ranked as Mn > Ni > Pb ≈ Zn ≈ Cr > Cd. The acidsoluble fraction (un-fixed AN) content of Mn, Ni, Zn, and AN in agricultural soils increased significantly. The risk assessment code shows that the risk level of Mn in agricultural soils changed from medium to high; Ni and Zn in surface soils changed from low to medium. These results indicated that the leaching from EMR would significantly increase the ecological risk of HMs in surrounding agricultural soils, and the large release of AN would pose a great threat to aquatic systems if not properly addressed.

Possibility of Using Vitreous Enamel Waste in the Construction Industry as the Concept of Cleaner Production

Waste vitreous enamels from the heating device production process were used for partial replacement of cement in the mortar and concrete production industry. This waste, due to the high content of heavy metals, is classified as hazardous waste. At the same time, waste vitreous enamels possess pozzolanic activity and belong to class 15 (WEP—generated during the production process of heating devices, premix technology), that is 5 (WETM—generated during the production process of heating devices, classic technology) of pozzolanic materials. The purpose of this research was to develop new composites from these wastes to reduce the deposition of the toxic compounds and reduce their environmental impact. The chemical and physical-chemical characterization and pozzolanic activity of the raw waste materials were studied by a mixture of complementary methods, as well as physical-mechanical characterization and a leaching test of mortar and concrete composites. The results indicate that the replacement of cement with WEP up to 30%, or with WETM up to 20% does not significantly affect the quality of concrete in comparison to the quality of the reference concrete prepared with 100% cement. The leaching test showed no significant release of toxic elements for both obtained composites.

Effects of Carbonation and Saturation on the Leaching Characteristics of Recycled Concrete Aggregates

Abstract This study assessed the efficacy of water leach tests (WLTs) and pH-static leach tests in evaluating the leaching behavior of distinctly carbonated recycled concrete aggregates (RCA). The leaching of barium (Ba), calcium (Ca), chromium (Cr), magnesium (Mg), and sulfate (SO4) from seven RCA samples were studied. WLTs at several liquid-to-solid ratios (L/S) and pH-static leach tests were conducted to examine the effects of carbonation on the release of elements. In addition, a novel experimental approach was introduced to gauge the impact of moisture saturation on the leaching attributes of RCA. The saturation effect on the leaching potential was explored by inducing eight different matric suctions in laboratory-compacted RCA cores. Moreover, geochemical modeling was performed to evaluate the leaching mechanisms of the elements. Results showed that a carbonation-based leaching assessment of RCA could be premised on laboratory WLTs and pH-static leach tests. Ba and Ca leaching decreased while Cr and SO4 leaching increased with the RCA degree of carbonation. The L/S ratio could be used as a substitute for RCA carbonation. At a higher L/S ratio, fresher and aged RCA samples had similar leaching fingerprints. The pH-dependent leaching of the elements was regulated by the RCA degree of carbonation, especially in the alkaline pH range. Irrespective of carbonation level, geochemical modeling suggested solubility-controlled leaching mechanisms. The leaching of metals from RCA was a dynamic process, and the changes in matric suction and consequently saturation could diversely influence the leaching characteristics of RCA.

МОДЕЛЮВАННЯ РОБОТИ ПІДСИЛЕНОГО ПОПЕРЕДНЬО НАПРУЖЕНОГО ЗГИНАЛЬНОГО ДЕРЕВ’ЯНОГО ЕЛЕМЕНТУ

An undeniable disadvantage of wood when using it in construction is its excessive flexibility. One of the ways to increase the stiffness of wooden elements is to use prestressing and reinforcement with stiffer elements. The manufacturing process of pre-stressed bending elements proposed by us is simple. However, determining the necessary effort, the necessary bending of the beam to ensure reliable operation, preventing the destruction of the element is quite difficult. One of the methods of prestressing is described, namely, the method by which the beam receives internal stresses due to the release of the bending element after the action of the external load by gluing reinforced elements. The principle of such tension can be described in the following sequence: 1. We create a bend in the bending element by applying an external load to the element. 2. We reinforce the lower zone of the bending element. At the same time, we need to know under which stress-strained state the reinforced element was installed, so that its operation can be predicted. 3. We remove the applied force with which we created the bend in the flexible wooden element, while the element wants to acquire its original shape, but this will be prevented by the armature, which will absorb part of the load and leave a small bend. It was established that the level of prestressing, namely the curvature acquired by the bending element after prestressing, depends on the initial curvature of the wooden element, as well as on the area and physical and mechanical characteristics of the materials reinforcing the beam zones. To determine the prestress, it is necessary to establish the stress-deformed states of the bending element, which occur after gluing and release of the external force. At the same time, 3 levels of the stress-strain state can be distinguished. 1. At the first stage, the compressed zone is more than the stretched zone. The relative deformations of the compressed lower zone, where the material is to be attached, is the initial start for the work of the reinforced element. 2. At the second stage, the external bending moment decreases, the internal redistribution of forces takes place, in addition to the moment perceived by the compressed and stretched zone, a moment also occurs in the stretched reinforced element. 3. The third stage is characterized by the absence of an external load, and this causes a balance between the internal forces of the bending prestressed element. The equilibrium equation for three stages was obtained. When using the element as a load-bearing structure, the cross-section in the element can be with both positive and negative curvature. The peculiarities of these two stress-strain states are manifested in the change in the position of the compressed and stretched zones. In the first case, the compressed zone is located in the lower part of the element and the upper part is occupied by the stretched zone. After the curvature changes its sign from negative to positive, the upper part becomes compressed, and the lower part becomes stretched. As a result of the simulation, it is possible to conclude that the cross-section of a bending wooden element undergoes 3 main stress-deformed states during prestressing and two during its operation

РАЗРАБОТКА КИШЕЧНОРАСТВОРИМЫХ МАТРИЧНЫХ ТАБЛЕТОК С ГУМИНОВЫМИ ПРОИЗВОДНЫМИ

Medicines based on compounds of iron, copper and zinc occupy a certain place in the pharmaceutical market. A lack of iron in the body can contribute to the development of iron deficiency anemia, and in the case of copper and zinc, a deficiency in the immune response and inflammation caused by lipid peroxidation, which ultimately leads to various joint diseases such as arthritis. The basis of the treatment and prevention of diseases is the use of chelates of salts of iron, copper and zinc, the effectiveness of which largely depends on their stability and the degree of release of trace elements in various parts of the gastrointestinal tract. Therefore, there is a need to create new long-acting drugs with a certain solubility and sufficient bioavailability. This study is devoted to the development of the optimal composition of iron, copper and zinc humate matrix tablets for oral administration.

Determining the sequence of elimination of impurity ions from the surface of historical cold iron weapons

Confirming the authenticity of historical cold weapons and determining their age is an urgent problem in practical examination. One of the promising directions for its solution is the experimental study of the process of elimination of impurity ions from iron, which occurs throughout the long history of life. This paper describes a model that explains the sequence of elimination of impurity ions from near-surface parts of the metal. Deformation indicators of the crystal lattice of iron were calculated and sorted in order of decreasing ionic radius of the impurity chemical element. A diagram of the deformation effect of impurity chemical elements on the volume-centered crystal lattice of iron was constructed. Ions that are larger in diameter are more actively eliminated from the surface layers of the metal, while ions that are smaller are removed to a lesser extent. With the help of the authors’ methodology, a study of the chemical composition of the surface of collection samples of iron cold weapons of the 20th, 19th, and 18th centuries was carried out. It has been established that a metal alloy made in the recent past ‒ up to 100 years ‒ is characterized by a very active release of impurity chemical elements on the surface when it is heated. Iron weapons made up to 200 years ago have a significantly lower ability to release chemical impurities because most of the latter have already been eliminated. At the same time, samples of cold weapons of this age already have microdefects in the form of cleavage cracks and caverns, so their surface contains a significant number of compounds of eliminated chemical elements that have accumulated during the long history of their use. Older cold weapons, made 300 years ago or earlier, have impurity ions that are smaller than ferric ions, particularly silicon. The results of the research are important for the identification and authentication of historical iron cold weapons