Search Results (25)

The treatment of contaminants from road infrastructure poses significant challenges due to their variable composition and the high concentrations of chloride ions, heavy metals, and oil-derived substances. Traditional methods for protecting groundwater environments are often insufficient. A promising alternative is permeable reactive barrier (PRB) technology, which utilizes recycled materials and construction waste as reactive components within the treatment zone of the ground. This paper delves into the potential of employing a composite (MIX) consisting of modified construction aggregate (as recycled material) and activated carbon (example of reactive material) to address environmental contamination from a mixture of heavy metals and chloride. The research involved chemical modifications of the road aggregate, activated carbon, and their composite, followed by laboratory tests in glass reactors and non-flow batch tests to evaluate the kinetics and chemical equilibrium of the reactions. The adsorption process was stable and conformed to the pseudo-second-order kinetics and Langmuir, Toth, and Redlich–Peterson isotherm models. Studies using MIX from a heavy metal model solution showed that monolayer adsorption was a key mechanism for removing heavy metals, with strong fits to the Langmuir (R² > 0.80) and Freundlich models, and optimal efficiencies for Cd and Ni (R² > 0.90). The best fit, at Cd, Cu, Ni = 0.96, however, was with the Redlich–Peterson isotherm, indicating a mix of physical and chemical adsorption on heterogeneous surfaces. The Toth model was significant for all analytes, fitting Cl and Cd well and Pb and Zn moderately. The modifications made to the composite significantly enhanced its effectiveness in removing the contaminant mixture. The test results demonstrated an average reduction of chloride by 85%, along with substantial removals of heavy metals: lead (Pb) by 90%, cadmium (Cd) by 86%, nickel (Ni) by 85%, copper (Cu) by 81%, and zinc (Zn) by 79%. Further research should focus on the removal of other contaminants and the optimization of magnesium oxide (MgO) dosage. Full article

Fusarium oxysporum is one of the main pathogens causing rice seedling blight disease. Revealing its pathogenic mechanism is of great significance for formulating prevention and control strategies for rice seedling blight disease. Copper transporting P-type ATPases (Cu-ATPase) is a large class of proteins located on the plasma membrane that utilize the energy provided by ATP hydrolysis phosphorylation to transport substrates across the membrane. It plays a crucial role in signal transduction, the maintenance of cell membrane stability, and material transport. The main function of Cu-ATPase is to maintain the homeostasis of copper in cells, which is essential for the normal growth and development of organisms. This study utilized the ATMT-mediated gene knockout method to obtain the knockout mutant ∆FoCrpA and the complementation strain ∆FoCrpA-C, which are highly homologous to the P-type heavy metal transport ATPase family in F. oxysporum. The results showed that, compared with the wild-type strain, the knockout mutant ∆FoCrpA had a lighter colony color; a reduced tolerance to copper ion, osmotic, and oxidative stress; a weakened ability to penetrate glass paper; and decreased pathogenicity. However, there was no significant difference in pathogenicity and other biological phenotypes between the complementation strain ∆FoCrpA-C and the wild-type strain. In summary, the FoCrpA gene is involved in osmotic and oxidative stress, affecting the invasion and penetration ability and pathogenicity of F. oxysporum, laying a theoretical foundation for understanding the development and pathogenic mechanism of F. oxysporum. Full article

The study is focused on the analysis of black crust and soiling on the building materials of the medieval Lipowiec Castle in southern Poland. The castle was constructed using local, partly dolomitic limestones and dolomites, supplemented with other limestones and bricks, during 20th-century renovations of the castle ruins. The crust and soiling components, secondary mineral phases, and particulate matter of anthropogenic origin were analysed using Raman micro-spectroscopy (RS) and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). The crust, mostly composed of gypsum and other sulphate phases, was found to contain carbonaceous matter, spherical Si-Al glass particles, and iron oxides, with admixtures of other elements, including heavy metals, as well as irregularly shaped particles containing various metals. These components reflect the air pollution in the region, related to the combustion of solid fuels in both industrial power plants and local domestic furnaces, Zn-Pb ore mining (operational until 2021), and smelting in the neighbouring industrial centre. Despite its location in a rural area, the castle has been exposed to pollution for an extended period due to its proximity to large industrial centres. Therefore, the crust analysed may serve as an environmental indicator of the nature of the air pollution in the region. Full article

Elevated concentrations of heavy metals in natural waters can cause significant ecological problems. It is therefore essential to ensure their removal from any water discharged into the environment immediately, especially in case of an accident, where there is a risk of releasing large quantities or high concentrations. The aim of this paper is to test a newly developed adsorbent for the removal of heavy metals from aqueous solutions—in particular, it is very fast adsorption, and thus efficiency, during clean-ups. The alkali-activated foamed zeolite adsorbent was laboratory-prepared and -tested in both batch and flow-through arrangements on single and multi-component solutions and compared with natural zeolite. The experimental setup for batch adsorption consisted of a set of samples and solutions containing iron, cobalt, manganese, zinc and nickel. The samples were put on a horizontal shaker with a 500 mg adsorbent loading in a 50 mL solution. The column adsorption experimental setup consisted of a glass column with an inside diameter of 15 mm and a bed length of 165 mm. A measured amount of each adsorbent was added to the column to achieve a filter fixed-bed height of 160 mm. The high efficiency of the tested adsorbent on various heavy metals was confirmed. The adsorbent has a high potential for use in decontamination processes, water protection and landscape revitalization. Due to its rapid precipitation and subsequent fixation of metal cations in the form of insoluble oxide or hydroxide, it can be used as an emergency adsorbent, the great advantage of which is its low production cost and natural origin. Full article

In recent years, great progress has been made in the technology of high-purity and ultra-dry tellurite glasses, which has enabled the creation of high-purity single-mode tellurite fibers doped with rare-earth ions. This technology has made it possible to demonstrate laser generation in the range of about 2.7 μm in erbium-doped tungsten tellurite fibers. In this paper, we present an experimental study of broadband amplification in erbium-doped zinc-tellurite fibers. Zinc-tellurite glasses containing modifying components, such as Na₂O, La₂O₃, Bi₂O₃, or rare-earth metal oxides, are known to have noticeably lower phonon energy than heavy metal-tellurite systems, namely, tungsten tellurite glasses, which leads to better lasing output. The on-off gain of 30- and 60-cm long zinc-tellurite fibers has been measured in a wide range of diode pump powers. It has been shown for the first time that the amplification band is essentially extended, with pump power reaching over 250 nm (2600–2850 nm) at a peak power of about 40 W for a 30-cm long fiber. Full article

Rare earth elements (REE) are indispensable for industries such as magnetic, phosphorus, metal alloys, catalysts, ceramics, glass, polishing and defense systems due to their unique physical and chemical properties. Currently, China is the largest supplier in the world, accounting for production of more than 95% of the world’s rare earth oxides (REO). To reduce the influence of China on the REE market, some countries have started to develop their own national strategies for the production and use of REE-bearing resources. Within the scope of this study, particle size, chemical, MLA, XRD, and SEM-EDS analysis were performed for material characterization, and shaking table, centrifugal, and magnetic separations were carried out for the beneficiation of Malatya/Kuluncak rare earth ore. The XRD analysis indicated that the representative sample consisted of major minerals such as albite, calcite, montmorillonite, muscovite, titanite, kaolinite, clinochlore, and aegirine. Parisite, bastnaesite, Zr-REE-Silicate, Fe-REE-Oxide, and Ca-Ti-Nb-REE-Oxide were detected as REE-bearing minerals by MLA. The chemical analysis resulted in a ∑REO grade of 3628 g/t, and the ore consisted mostly of light REEs. According to the results of the gravity separation for the coarsest fraction, about 11.3% by weight of the total feed was concentrated as a heavy product with 6437 g/t ∑REO content. As a result of magnetic separation, magnetic products with 5561 g/t and 6013 g/t ∑REO were obtained as coarse and fine fractions, respectively. Finally, the characterization studies and enrichment results were correlated, and very important and meaningful indications about the behavior of REE-bearing minerals were obtained. Full article

Radiation has become an essential part in medicine and researchers are constituently investigating radiation shielding materials that are suitable for different medical applications. Glass, due to its properties, has been considered an excellent radiation shield for such applications. One of the most common glasses used as a radiation shield is the ZnO-Bi₂O₃-B₂O₃-SiO₂ anti-radiation glass. Heavy metal oxides have many desirable properties such as high density, transparency to visible light, stability in air and water, high interaction cross section, high infrared transparency, and good absorption of radiation, which make them desirable to be used as modifiers with anti-radiation glass. Research has been focusing on environmentally friendly shielding material which leads to non-lead modifiers such as Na₂O, Al₂O₃, MgO, TiO₂, SrO, Sb₂O₃, and BaO, which have become more desired than PbO. So far, ZnO-Bi₂O₃-B₂O₃-SiO₂’s photon shielding properties have been studied experimentally with the addition of BaO at certain energies only. In this work, different heavy metal oxides are added as modifiers to ZnO-Bi₂O₃-B₂O₃-SiO₂ glass in order to investigate theoretically their effects on the shielding properties of the glass at a wide range of photon and neutron energies. Simulation is cost- and time-effective when it comes to investigating different compositions of glass and different modifiers with different weight percentages at any energy range for any type of radiation. Simulation could be considered the first step in order to identify the best mixture with the best weight fractions prior to any experimental investigations of other desired properties based on the needed application. In this work, the photon- and neutron-shielding capabilities of the ZnO-Bi₂O₃-B₂O₃-SiO₂ anti-radiation glass is investigated with different weight fractions of heavy metal oxides at wide photon and neutron energy ranges. Geant4, which is a Monte Carlo-based powerful toolkit, is used to find the mass attenuation coefficients (µm) of photons, as well as the effective removal cross sections (ΣR) of neutrons, of all the investigated samples in the studied energy range. Full article

Hatiya is the second largest island of Bangladesh and is situated near the Meghna River estuary in the central coastal zone of Bangladesh. This island hosts a few scenic beaches with a huge deposit of mineral sands. Representative mineral sand samples from various beaches of this island were collected during the year 2019, and analyzed for different mineralogical contents using state-of-the-art techniques, such as WD-XRF, XRD, SEM and EDX. This study determined various mineralogical contents, such as SiO₂ (73.58%), micas (40.30%), Al₂O₃ (12.13%), TiO₂ (0.56%), MgO (1.31%), Fe₂O₃ (4.71%), K₂O (3.1%), Na₂O (1.92%), CaO (3.16%), some earth metals, and heavy minerals, such as ilmenite (14.77%), garnet (11.02%), rutile (14.94%), magnetite (15.26%), and zircon (13.63%), were identified in the analyzed samples. It is suggested that the studied sand can be utilized as a raw material in the glass industry, due to its high SiO₂ content. The approximate prices of heavy and light minerals, such as garnet (USD 75–USD 210/mt), ilmenite (USD 110/mt), magnetite (USD 84/mt), rutile (USD 840/mt), zircon (USD 1050/mt) and micas (USD 109/mt), some oxides such as K₂O (USD 350–400/mt), CaO (USD 350–450/mt), Al₂O₃ (USD 1000-USD 1300/mt), TiO₂ (USD 4000–4500/mt), and Fe₂O₃ (USD 650–1500/mt), and some other heavy metals (Rb, Th, Ba, V, Cr, Cs, Ni and Co), indicates a great economic value of the sand of the Hatiya Island beaches. This study recommends that Hatiya Island’s minerals should be mined responsibly and used effectively, to enhance the nation’s economy. Full article

The effect of BaF₂, MgF₂, and AlF₃ on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]₄ and [GeO]₆ units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF₂. The ²⁷Al MAS NMR spectrum of BGG glass with AlF₃ suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the ⁴I_13/2→⁴I_15/2 transition of Er³⁺ ions increases in the BGG + MgF₂ glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties. Full article

Co-treatment for two kinds of hazardous solid waste is an effective method to reduce cost and increase recycle efficiency of value resource. This work developed an integrated process based on capture of red mud (RM) and a one-step heat-treatment process to efficiently recover PGMs from spent auto-catalysts (SAC) and reuse RM simultaneously. Firstly, the iron oxide in RM was reduced to metallic iron to capture PGMs by the reduction process, without the addition of an extra reducing agent, since SAC contained abundant organic volatiles. Then, the mixed waste of SAC and RM was melted under high temperature with additives of CaO and H₃BO₃. More than 99% of PGMs can be extracted under the optimal conditions of 40–50 wt% of RM addition, 14 wt% of H₃BO₃ addition, 0.7–0.8 of basicity, 1500 °C of temperature, and 40 min of holding time. In addition, PGM content in obtained glassy slag was less than 1 g/t. The mechanism of iron trapping PGMs was also discussed in detailed, which mainly contained two stages: migration of PGMs and separation of PGM-bearing alloy and slag phases. Besides, the obtained glassy slag was further prepared into glass-ceramic by a one-step heat-treatment process. It was found that the prepared glass-ceramic has good thermostability and an excellent stabilizing effect on heavy metals. Overall, the results indicated that the developed integrated smelting–collection process is an efficient and promising method for the reutilization of SAC and RM. Full article

The physical, structural, thermal, and optical properties of heavy metal (Ho³⁺) oxide incorporated lithium-boro-phosphate glass prepared utilizing melt quenching process are presented in this paper as a function of dopant concentration. To support the findings of the FTIR and DSC studies, many theoretical, experimental, physical, and optical parameters were calculated. XRD and FTIR measurements revealed the prepared glasses’ amorphous nature and the presence of significant borate functional groups. The optical band gap, Urbach energy, and steepness characteristics were tested to validate the structural results. The emission spectrums were recorded in the prepared glasses for an excitation of 450 and 550 nm to find powerful emission color. The color co-ordinates (0.33, 0.41) were found to be quite comparable to white light color co-ordinates. The present glasses can, therefore, be ideal candidates for possible applications with light-emitting diodes. Full article

TiO₂ is an important oxide for property modifications in the conventional soda lime silicate glass family. It offers interesting optical and mechanical properties, for instance, by substituting heavy metals such as lead in consumer glasses. The compositional effects on the hardness, reduced elastic modulus and crack resistance as determined by indentation of chemically strengthened (CS) TiO₂-doped soda lime silicate glass was studied in the current paper. The CS, which was performed by a K⁺ for Na⁺ ion exchange in a molten KNO₃ salt bath at 450 °C for 15 h, yielded significant changes in the indentation mechanical properties. The hardness of the glass samples increased, and this was notably dependent on the SiO₂, CaO and TiO₂ content. The reduced elastic modulus was less affected by the CS but showed decrease for most samples. The crack resistance, an important property in many applications where glasses are subjected to contact damage, showed very different behaviors among the series. Only one of the series did significantly improve the crack resistance where low CaO content, high TiO₂ content, high molar volume and increased elastic deformation favored an increased crack resistance. Full article

The direct influence of La³⁺ ions on the gamma-ray shielding properties of cobalt-doped heavy metal borate glasses with the chemical formula 0.3CoO-(80-x)B₂O₃-19.7PbO-xLa₂O₃: x = 0, 0.5, 1, 1.5, and 2 mol% was examined herein. Several significant radiation shielding parameters were evaluated. The glass density was increased from 3.11 to 3.36 g/cm³ with increasing La³⁺ ion content from 0 to 2 mol%. The S5 glass sample, which contained the highest concentration of La³⁺ ions (2 mol%), had the maximum linear (μ) and mass (μ_m) attenuation coefficients for all photon energies entering, while the S1 glass sample free of La³⁺ ions possessed the minimum values of μ and μ_m. Both the half value layer (T_1/2) and tenth value layer (TVL) of all investigated glasses showed a similar trend of (T_1/2, TVL)_S1 > (T_1/2, TVL)_S2 > (T_1/2, TVL)_S3 > (T_1/2, TVL)_S4 > (T_1/2, TVL)_S5. Our results revealed that the S5 sample had the highest effective atomic number (Z_eff) values over the whole range of gamma-ray energy. S5 had the lowest exposure (EBF) and energy absorption (EABF) build-up factor values across the whole photon energy and penetration depth range. Our findings give a strong indication of the S5 sample’s superior gamma-ray shielding characteristics due to the highest contribution of lanthanum oxide. Full article

Characteristics of tellurite-tungstate-antimonate glasses containing heavy metal oxide were investigated in detail using two methods: the MCNPX Monte Carlo code and the Phy-X/PSD platform. The influence of Sm₂O₃, translocating with TeO₂ at ratios of 0.2, 0.5, 0.8, 1, and 1.5 mol% on radiation shielding properties of glasses, was set forth with five glass structures determined according to the (75-x)TeO₂-15Sb₂O₃-10WO₃-xSm₂O₃ glass composition. Densities of the glasses were prepared by doping a low ratio of Sm₂O₃ that varied between 5.834 and 5.898 g/cm³. Sample densities, which have an important role in determining radiation shielding character, increased depending on the increase in Sm₂O₃ concentration. Effective removal cross-section (∑R) values against fast neutrons, as well as linear and mass attenuation coefficients, half-value layer, mean free path, variation of effective atomic number against photon energy, exposure, and energy built-up factors, were simulated with the help of these two methods. As a result of these estimates, it can be concluded that values obtained using both methods are consistent with each other. From the obtained values, it can be concluded that the SM1.5 sample containing 1.5 mol% would have the most efficient role in radiation shielding. An increase of Sm₂O₃ resulted in a significant increase in linear and mass attenuation coefficients and effective removal cross-section values belonging to fast neutrons and, in addition, resulted in a decrease in the half value layer. Doping HMO glasses with Sm₂O₃ was observed to contribute directly to the development of radiation shielding properties of the glass. Full article

In this study, a group of heavy metal oxide glasses with a nominal composition of 55B₂O₃ + 19.5TeO₂ + 10K₂O + (15−x) PbO + xAl₂O₃ + 0.5Eu₂O₃ (where x = 0, 2.5, 5, 7.5, 10, 12.5, and 15 in wt.%) were investigated in terms of their nuclear radiation shielding properties. These glasses containing lanthanide-doped heavy metal oxide were envisioned to yield valuable results in respect to radiation shielding, and thus a detailed investigation was carried out; the obtained results were compared with traditional and new generation shields. Advanced simulation and theoretical methods have been utilized in a wide range of energy regions. Our results showed that the AL0.0 sample with the highest PbO contribution had superior shielding properties in the entire energy range. The effective removal of cross-sections for fast neutrons (Σ_R) was also examined. The results indicated that AL5.0 had the greatest value. While increasing the concentration of Al₂O₃ in samples had a negative effect on the radiation shielding characteristics, it can be concluded that using PbO in the Eu³⁺ doped heavy metal oxide glasses could be a useful tool to keep gamma-ray shielding properties at a maximum level. Full article