Search Results (5)

Drawing upon an understanding of the distribution characteristics of groundwater in the Taoshan rock mass within the Yushan Uplift region of southern Jiangxi, this study utilizes mathematical statistics, ion ratio coefficients, factor analysis, and mineral dissolution equilibrium methods to characterize in detail the hydrochemical features of groundwater in humid mountainous areas. Furthermore, the study delves into the lithological source control and the primary natural mechanisms that underlie these characteristics. The results indicate that the average pH of groundwater in the study area is 7.13, classifying it as weakly alkaline. The dominant cations are Ca²⁺ and Na⁺, accounting for 61% and 26% of the total cations, respectively, while the dominant anion is HCO₃⁻, constituting 91% of the total anions. The total dissolved solids (TDS) range from 37.93 mg/L to 228.16 mg/L, indicating low mineralization. The groundwater types are primarily HCO₃-Ca·Na and secondarily HCO₃-Ca. The groundwater type is mainly controlled by rock weathering, with the primary ion sources influenced by the weathering and dissolution of silicate rocks, supplemented by contributions from carbonate rock dissolution. Ion ratio analysis further confirms that the major ions in groundwater predominantly originate from the weathering of silicate minerals, with minimal influence from human activities. Na⁺, K⁺, and H₂SiO₃ are primarily derived from the weathering and dissolution of silicate rocks, while the weathering and dissolution of carbonate rocks (e.g., calcite) significantly contribute to Ca²⁺ and Mg²⁺. TDS shows significant positive correlations with Mg²⁺, SO₄²⁻, HCO₃⁻, Na⁺, and Ca²⁺, with the most pronounced correlations observed between TDS and Ca²⁺ and HCO₃⁻, exhibiting a correlation coefficient of 0.89. Factor analysis reveals that the first principal component has relatively high loadings for TDS, Ca²⁺, HCO₃⁻, Mg²⁺, and SO₄²⁻. Additionally, among 45 natural spring water samples, 36 exhibit metasilicic acid (H₂SiO₃) concentrations exceeding 30 mg/L, meeting the standards for metasilicic acid mineral water and demonstrating significant potential for development and utilization. Full article

This study employed hydrochemical data, traditional hydrogeochemical methods, inverse hydrogeochemical modeling, and unsupervised machine learning techniques to explore the hydrogeochemical traits and origins of groundwater in the Changbai Mountain region. (1) Findings reveal that predominant hydrochemical types include HCO₃⁻Ca·Mg, HCO₃⁻Ca·Na·Mg, HCO₃⁻Mg·Na, and HCO₃⁻Na·Mg. The average metasilicic acid content was found to be at 49.13 mg/L. (2) Rock weathering mechanisms, particularly silicate mineral weathering, primarily shape groundwater chemistry, followed by carbonate dissolution. (3) Water-rock interactions involve volcanic mineral dissolution and cation exchange adsorption. Inverse hydrogeochemical modeling, alongside analysis of the widespread volcanic lithology, underscores the complexity of groundwater reactions, influenced not only by water-rock interactions but also by evaporation and precipitation. (4) Unsupervised machine learning, integrating SOM, PCA, and K-means techniques, elucidates hydrochemical types. SOM component maps reveal a close combination of various hydrochemical components. Principal component analysis (PCA) identifies the first principal component (PC1), explaining 48.15% of the variance. The second (PC2) and third (PC3) principal components, explain 13.2% and 10.8% of the variance, respectively. K clustering categorized samples into three main clusters: one less influenced by basaltic geological processes, another showing strong igneous rock weathering characteristics, and the third affected by other geological processes or anthropogenic factors. Full article

The further development of lithium-ion batteries leads to an improvement in power densities as well as safety and thus requires an optimization of the materials used. For this purpose, among other approaches, the anode materials are doped with silicon oxide or metallic silicon is used as the anode. However, silicon is a semimetal and is known to lead to the formation of jelly-like fluids in hydrometallurgical processes under certain conditions. This publication evaluates which parameters are responsible for this viscosity change in the leaching solutions during the recycling of lithium-ion batteries and examines the corresponding reaction mechanism behind this phenomenon. Furthermore, the leaching efficiency for the valuable metals nickel, cobalt, lithium and manganese is evaluated and the influence of different silicon contents in the solution is investigated. It could be shown that, especially the simultaneous presence of H₂SO₄, H₂O₂ and Si or SiO_2, lead to a significant viscosity increase due to the formation of metasilicic acid and, accordingly, the leaching efficiencies of the valuable metals are negatively influenced. Full article

Hydroxyalkylation of the mixture of metasilicic acid and cellulose with glycidol and ethylene carbonate leads to a polyol suitable to obtain rigid polyurethane foams. The composition, structure, and physical properties of the polyol were studied in detail. The obtained foams have apparent density, water absorption, and polymerization shrinkage, as well as heat conduction coefficients similar to conventional, rigid polyurethane foams. The polyols and foams obtained from environmentally unobtrusive substrates are easily biodegradable. Additionally, the obtained foams have high thermal resistance and are self-extinguishing. Thermal exposure of the foams leads to an increase of the compressive strength of the material and further reduces their flammability, which renders them suitable for use as heat insulating materials. Full article

Two polyol raw materials were obtained in the conducted research, one based on metasilicic acid (MSA), the other based on poly(lactic acid) (PLA) waste. The obtained polyols were characterized in terms of their applicability for the production of rigid polyurethane foams (RPUFs). Their basic analytical properties (hydroxyl number, acid number, elemental analysis) and physicochemical properties (density, viscosity) were determined. The assumed chemical structure of the obtained new compounds was confirmed by performing FTIR and ¹H NMR spectroscopic tests. Formulations for the synthesis of RPUFs were developed on the basis of the obtained research results. A mixture of polyols based on MSA and PLA in a weight ratio of 1:1 was used as the polyol component in the polyurethane formulation. The reference foam in these tests was a foam that was synthesized only on the basis of MSA-polyol. The obtained RPUFs were tested for basic functional properties (apparent density, compressive strength, water absorption, thermal conductivity coefficient etc.). Susceptibility to biodegradation in soil environment was also tested. It was found that the use of mixture of polyols based on MSA and PLA positively affected the properties of the obtained foam. The polyurethane foam based on this polyol mixture showed good thermal resistance and significantly reduced flammability in comparison with the foam based MSA-polyol. Moreover, it showed higher compressive strength, lower thermal conductivity and biodegradability in soil. The results of the conducted tests confirmed that the new foam was characterized by very good performance properties. In addition, this research provides information on new waste management opportunities and fits into the doctrine of sustainable resource management offered by the circular economy. Full article