Search Results (396)

This article presents a comprehensive study of the nitrogen-radon thermal mineral waters of the Jety-Oguz area, located in the southeastern part of the Issyk-Kul intermountain artesian basin (Northern Tien Shan). Based on new data from chemical and isotopic (δ¹⁸O, δD) analyses of natural waters (lake, river, and mineral) and the chemical composition of the water-bearing rocks, we identify the formation mechanisms of mineral waters with diverse composition, total dissolved solids (TDS), and temperature. Three main genetic types have been identified: (1) saline, high-TDS (up to 12.8 g/L) chloride sodium-calcium thermal waters (up to 32 °C). These waters are of meteoric origin and circulate within Middle Carboniferous carbonate rocks, acquiring their unique composition at depths of up to 3.0 km, where reservoir temperatures reach ~105 °C; (2) chloride-sulfate sodium-calcium waters (0.5 g/L, fresh, 22 °C), formed in alluvial deposits within the zone of active water exchange; and (3) low-TDS (1.8 g/L, brackish) waters of mixed composition, resulting from the mixing of a deep fluid with infiltrating meteoric waters. Isotopic data confirm a meteoric origin for all studied waters, including the high-TDS thermal types. The chemical composition diversity is attributed to several processes: mixing between the deep, high-TDS fluid and low-TDS infiltration waters, intense dissolution of evaporite rocks, and water–rock interaction. These findings are crucial for understanding the genesis of mineral waters in the Tien Shan intermountain basins and provide a scientific basis for their sustainable balneological exploitation. Full article

This study examines the structural, chemical, and thermal properties of biochars from slow pyrolysis of hardwood (HW), corn cob (CC), and wheat straw (WS) at 400 °C and 700 °C, evaluating their potential in environmental and industrial applications. A combination of spectroscopic, crystallographic, thermal, and microscopic techniques was employed to monitor the degradation of biomass components and the development of the carbonaceous matrix. The results show that pyrolysis temperature has a significant impact on the properties of biochar. Higher temperatures (700 °C) increased the pH (up to 10.3 for WS700), the carbon content (e.g., 89.8% for HW700), the ash content (up to 24.8% for WS700), and the specific surface area (e.g., 306.87 m²/g for CC700) while decreasing polar functional groups and volatile matter (as confirmed by FTIR). SEM showed enhanced porosity at 700 °C, which was supported by BET analysis. XRD and Raman showed increased graphitization and structural order with temperature, especially for HW and CC biochars, while WS biochars retained mineral components like SiO₂ and CaCO₃. TGA analysis showed improved thermal stability at 700 °C only for biochar derived from wheat straw, while HW and CC biochars showed similar total mass loss regardless of pyrolysis temperature. These biochars exhibit high potential for soil remediation (high pH), water purification (large surface area), and carbon storage (high aromaticity), with HW700 and CC700 also suitable for high-temperature industrial applications due to their stability. Full article

Health tourism, including spa-based treatments, is an important segment of global travel, and its growth reflects increasing demand for experiences that combine physical well-being with contact with nature. Polish health spa resorts are rich in balneological resources such as mineral and thermal waters, peloids, and therapeutic gases, and they offer a variety of products and services based on geoheritage. This paper introduces the concept of geoproducts—goods and services inspired by abiotic nature—and explores their role in spa tourism and sustainable regional development. Through questionnaire surveys conducted in 48 Polish spa towns, the study examines how these resources are promoted and exploited, the forms and functions of local geoproducts, and the barriers to their dissemination. The results show that, although most spas acknowledge the value of geoheritage, promotion primarily employs traditional formats and is limited in educational content. Nevertheless, there is strong local interest in developing geotourism and geoeducation, especially through the creation of unique, regionally rooted products. The study underlines the potential of geoproducts to enhance spa attractiveness, support local economies, and contribute to broader environmental awareness. Full article

This study presents a cradle-to-grave Life Cycle Assessment (LCA) and cost analysis of next-generation low-temperature district heating networks based on water-condensed electric booster heat pumps. The research, conducted within the ENEA Portici Research Center framework, evaluates multiple case studies to assess environmental and economic sustainability. The system boundaries include heat generators (geothermal heat pump, solar thermal, and photovoltaic–thermal hybrid), network configurations (tree vs. ring), supply temperatures (25 °C vs. 45 °C), and renewable electricity shares (0–100%). Environmental impacts were quantified using the Environmental Footprint 3.1 method, focusing on key indicators such as climate change, resource use, and human toxicity. The results show that supply temperature is a critical factor: 45 °C scenarios lead to notably higher impacts, while network configuration has only marginal effects. Among generation technologies, the photovoltaic–thermal system proved the most sustainable, despite higher investment costs, whereas the solar thermal system displayed the largest environmental burden but lower costs. Geothermal systems showed intermediate performance, with notable impacts from mineral resource use. Renewable electricity integration consistently improved environmental outcomes, reducing climate change impacts by up to 10%. Storage system comparison revealed lithium iron phosphate (LFP) batteries as the most advantageous solution for electrical storage, and phase-change materials (PCM), particularly Rubitherm15, as the most environmentally favorable option for thermal storage, although traditional water tanks remain more cost-effective. Overall, the study highlights the crucial role of renewable integration and temperature optimization in enhancing the eco-efficiency of low-temperature district heating networks, providing guidelines for future sustainable design and deployment. Full article

The persistence of organochlorine pesticides, such as Aldrin and Dieldrin, in water bodies worldwide necessitates the development of efficient Advanced Oxidation Processes (AOPs) for water treatment or remediation. However, comparative studies evaluating the performance of distinct plasma discharge geometries against acoustic cavitation for the mineralization of these specific chlorinated cyclodienes remain scarce. This study investigates the comparative efficacy of four non-thermal technologies, ultrasound, dielectric barrier discharge (DBD) plasma, glow discharge plasma, and corona discharge plasma, for the simultaneous degradation of Aldrin and Dieldrin in a model contaminated aqueous solution (5 μg/L). All experiments followed a 3²-factorial design, and the residual concentrations of these pesticides were quantified by GC-MS after Solid-Phase Microextraction (SPME). All four methods achieved high degradation efficiencies, ranging from 92.5% to 100% for Aldrin and 92.6% to 99.2% for Dieldrin. Corona discharge plasma achieved the highest performance, resulting in 100% removal of Aldrin. However, ultrasound proved to be the most advantageous, achieving a 98% removal efficiency for both pesticides under its mildest conditions (3125 W/L ultrasonic power density for 3 min). The study confirmed that while Aldrin is highly susceptible to these technologies, Dieldrin remains the limiting factor for regulatory compliance. Chemical analysis did not conclusively identify any organic degradation by-products, suggesting that these AOPs may promote complete mineralization of the pollutants. Full article

Rice husk is a lignocellulosic biomass rich in silica, which, when disposed of inappropriately, represents an environmental hazard. This study investigated the application of deep eutectic solvents (DES) as a green and efficient approach to the rice husk fractionation, combining the selective dissolution of lignin and sugars with the purification of the silica-rich inorganic fraction. Six different DES were produced from choline chloride or betaine with different hydrogen bond donors and characterized for water content and pH. The DES based on carboxylic acids was more acidic, which favored the cleavage of ester and glycosidic bonds in the biomass. The TGA, XRF, SEM, and XRD analyses revealed that the lactic acid-based DES promoted better removal of lignin and mineral impurities, resulting in a purer silica with an amorphous morphology. The 110 °C condition was the most effective in preserving the thermal integrity of the organic (sugars and lignin) and inorganic (silica-rich ash) fractions. The results highlight the potential of DES as selective, sustainable, and tunable solvents for the valorization of agricultural waste, achieving biosilica with SiO₂ purity exceeding 80% and lignin removal above 70%, reinforcing the potential of DES as sustainable solvents for agricultural waste valorization. Full article

At present, phosphogypsum, as an industrial by-product, is a solid waste in phosphoric acid production, and its accumulation has caused serious environmental pollution. Furthermore, due to the insufficient insulation properties of traditional wall materials, the issue of a rising proportion of building energy consumption in total social energy consumption has become increasingly pressing. The study investigated vitrified beads as a light aggregate and phosphogypsum, mineral powder, and quicklime as an inorganic composite cementitious system to prepare the phosphogypsum-based lightweight thermal insulation material. The effect mechanism of the initial material ratio on the mechanical properties and micro-morphology of insulation materials was studied by macroscale mechanical property testing, X-ray diffraction, and scanning electron microscopy. Meanwhile, in order to meet the performance indexes specified in relevant standards, insulation materials were modified by adding sulfate aluminate cement, basalt fibers, and a waterproof agent to improve the strength, toughness, and water resistance. Based on the single-factor experimental design, the optimal dosage of various admixtures was obtained. The results indicated that the optimal properties of the sample were achieved when the binder–bead ratio was 1:4, the water–binder ratio was 1.6, the dosage of hydroxypropyl methylcellulose was 0.1%, and the solid content of waterborne acrylic emulsion was 24%. The optimal dosages of cement and fibers were 8% and 0.9%, respectively. The cement hydration products and gypsum crystals lapped through each other, filling the pores in the matrix and increasing the strength of the sample. In addition, the fibers could form a disordered network structure inside the matrix, disperse external force, weaken the stress concentration at the tip of internal cracks, and significantly improve the toughness of the modified sample. By incorporating 2.0% paraffin emulsion in the mortar and spraying 5 dilutions of sodium methyl silicate on the external surface, dense protective layers were formed both inside and outside the modified sample. The water absorption rate reduced from 30.27% to 23.30%, and the water resistance was increased to satisfy the specified requirement for the insulation material. Full article

This study presents the first comprehensive investigation of direct supercritical water oxidation (SCWO) of microalgae biomass integrated with photobioreactor oxygen recovery for sustainable energy production. Laboratory-scale experiments were conducted on Nannochloropsis gaditana at optimized conditions (650 °C, 24 MPa, 1 min residence time), achieving extraordinary conversion efficiency of 99.99% at biomass concentrations as low as 0.5 wt%. Process simulation using Aspen Plus demonstrated that this integrated photobioreactor-SCWO system can recover oxygen produced during photosynthesis, reducing compressor energy demands by 10–15% compared to conventional air-fed systems. The coupled system achieved net thermal power outputs of 47–66 kW from a 1 kg/min microalgae feed at 5–10 wt% biomass concentration, corresponding to an overall system thermal efficiency of approximately 18%. CO₂ recovery via mono-ethanolamine absorption enabled 70–80% carbon cycle closure, while simultaneous nutrient recycling through the aqueous phase supports sustainable circular economy principles. This coupled photobioreactor-SCWO process represents an efficient pathway for energy recovery from wet microalgae biomass, eliminating the energy-intensive drying requirement (typically 60–70% of conventional processing energy) and achieving complete mineralization of organic compounds. The system demonstrates technical and energetic viability for scaling to pilot demonstration scale. Full article

The growing demand for sustainable and circular construction materials has increased interest in reusing by-products from municipal solid waste incineration. Due to the variability in the chemical composition of bottom ash (BA) between different plants, sampling seasons, and particle sizes, an individualized approach depending on its origin is essential. This study examines the potential of BA as a binding material in composite structures. Composites were prepared from BA fractions of different granulometries, including ground and thermally treated material. Compressive strength tests and structural analyses of density, porosity, and water permeability were performed to evaluate the influence of particle size and heat treatment on binding activity. The results show that smaller particle sizes significantly improved compressive strength, while the highest strength was obtained for samples calcined at 1000 °C, with an average increase of 84% compared to untreated material. Thermal treatment enhanced binding activity through the mobilization of hydration-active compounds bound in non-reactive mineral phases formed during water cooling and also increased water permeability due to the breakdown of porous structures. These findings confirm the potential of BA as a secondary binder in construction materials; however, further research is needed to improve its reactivity and mechanical performance. Full article

Pipeline insulation is critical for energy-efficient building heating systems, as moisture ingress significantly degrades thermal performance and increases energy losses. This study experimentally evaluated how quality characteristics of mineral wool affect the thermal performance of pipe insulations (wired mats) at temperatures ranging from 20 °C to 85 °C with moisture content up to 12% by weight. Thermal conductivity measurements were performed on two representative samples using the “guarded hot pipe” and direct water injections. Thermal conductivity measurements confirmed the expected increase with rising temperature and moisture content for both samples. In a dry state, quality parameters have practically no effect on the thermal conductivity (0.036–0.041 W∙m⁻¹·K⁻¹). In a low-temperature regime, the inferior quality sample (Sample A) at a maximum moisture content of 12% exhibited thermal conductivity of 0.042 W∙m⁻¹·K⁻¹, and the sample with the best hydrophobic treatment (Sample B) had a thermal conductivity of 0.050 W∙m⁻¹·K⁻¹. At an elevated temperature at a moisture content of 12%, Sample A and Sample B had thermal conductivity of 0.077 W∙m⁻¹·K⁻¹, and 0.109 W∙m⁻¹·K⁻¹, respectively. The results suggest that highly hydrophobic materials are advantageous only in high-temperature applications where rapid moisture removal occurs after short-term ingress, providing critical data for optimizing insulation selection and improving energy conservation in heating networks. Full article

Omniphobic membranes have gained extensive attention for mitigating membrane wetting in robust membrane separation owing to the super-repulsion toward water and oil. In this study, a Teflon/PAI composite membrane with omniphobic characteristics was prepared by a vacuum-assisted dip-coating strategy on the PAI hollow fiber membrane. A series of characterizations on morphological structure, surface chemical composition, wettability, permeability, mechanical properties, and stability were systematically investigated for pristine PAI and Teflon/PAI composite membranes. Subsequently, the experiment was conducted to explore the oil–gas separation performance of membranes, with standard transformer oil containing dissolved gas as the feed. The results showed that the Teflon AF2400 functional layer was modified, and C-F covalent bonds were introduced on the composite membrane surface. The Teflon/PAI composite membrane exhibited excellent contact angles of 156.3 ± 1.8° and 123.0 ± 2.5° toward DI water and mineral insulating oil, respectively, indicating omniphobicity. After modification, the membrane tensile stress at break increased by 23.0% and the mechanical performance of the composite membrane was significantly improved. In addition, the Teflon/PAI composite membrane presented satisfactory thermal and ultrasonic stability. Compared to the previous membranes, the Teflon/PAI composite membrane presented a thinner Teflon AF2400 separation layer. Furthermore, the omniphobic membrane demonstrated anti-wetting performance by reaching the dynamic equilibrium within 2 h for the dissolved gases separated from the insulating oil. This suggests an omniphobic membrane as a promising alternative for oil–gas separation in monitoring the operating condition of oil-filled electrical equipment online. Full article

Boreholes in the Teleghma region of northeastern Algeria discharge thermal water with temperatures between 40 and 49 °C and total dissolved solids (TDS) ranging from 570 to 940 mg/L. The stable isotope compositions range from –7.8‰ to –6.2‰ for δ¹⁸O and –52.6‰ to –43.3‰ for δ²H, indicating a meteoric origin. Based on these isotopic signatures, the water is classified as immature and undersaturated with respect to the equilibrium line on the Giggenbach Na–K–Mg ternary diagram. The water exhibits a sodium–chloride (Na–Cl) facies, closely associated with Triassic formations rich in evaporitic deposits. This association was confirmed by the IIGR method, which illustrates the chemical evolution of the hydrothermal fluid as it ascends from the karstic carbonate reservoir through conduits and traverses clay formations. Consequently, computed saturation indices and applied inverse modeling significantly contributed to understanding the interactions between the hydrothermal water and the traversed rock. At the local scale, halite dissolution is the primary mineral phase driving chemical changes. Regionally, however, the processes are dominated by gypsum dissolution and cation exchange reactions between calcium and sodium ions. These findings offer valuable insights into the geochemical processes that shape the Teleghma geothermal system, with implications for resource management and potential applications. Full article

Natural sulfur compounds found in various mineral spring waters have attracted considerable interest due to their possible health benefits and healing qualities. Key substances such as hydrogen sulfide (H₂S), sulfate (SO₄²⁻), and thiosulfate (S₂O₃²⁻) are essential to numerous physiological functions. This overview delves into the biochemical pathways through which these sulfur compounds exert their influence, emphasizing their roles as antioxidants, anti-inflammatories, and detoxifying agents. Furthermore, it investigates the therapeutic promise of mineral waters rich in sulfur for various diseases like arthritis, skin ailments, and heart diseases. Emerging studies indicate that regular use or topical application of these waters could enhance health outcomes and aid in the prevention of a multitude of diseases. Nonetheless, additional research is required to clarify sulfur water’s mechanisms of action and to develop standardized protocols for their therapeutic applications. This descriptive review highlights the significance of integrating natural sulfur compounds into comprehensive health strategies and advocates for ongoing investigation into their advantages in medical contexts. Full article

The basis of the construction industry is building materials with high-quality indicators in terms of physical, mechanical, and thermophysical characteristics, however, there are a number of issues affecting the quality of manufactured products. The development of the construction industry provides new opportunities for designing efficient construction facilities. To obtain enhanced design capabilities, it is very important to relieve the load on the structure, and this can be achieved by reducing the mass of materials without losing strength. This study investigates the enhancement of foam concrete through the combined incorporation of mineral fibers recycled from basalt insulation waste and complex polymer modifiers. The aim was to improve the material’s mechanical performance, durability, and pore structure stability while promoting sustainable use of industrial by-products. The experimental program included tests on density, compressive strength, water absorption, and thermal conductivity for mixtures of different densities (400–1100 kg/m³). Results demonstrated that the inclusion of mineral fibers and polymer modifiers significantly enhanced structural uniformity and pore wall integrity. Compressive strength increased by up to 35%, water absorption decreased by 25%, and thermal conductivity was reduced by 18% compared with the control mixture. Full article

Hydrogen-fuelled internal combustion engines (H₂ICEs) generate water vapour that can condense in the sump and form water-in-oil emulsions, altering lubricant performance. This study measures the viscosity–temperature behaviour, copper corrosivity, and boundary tribology of three commercial oils—synthetic (5W-40), semi-synthetic (10W-40), and mineral (15W-40)—emulsified with 5–40 wt% water and tested in both freshly emulsified and aged (3 months; clarified oil layer) states. In fresh emulsions, viscosity rose with water fraction. At 25 ^∘C and 40 wt%, the increase was 44.4% (5W-40), 78.7% (10W-40), and 81.2% (15W-40) versus the neat oils. Ageing drove viscosities toward the baseline, with the strongest effect observed for 15W-40, indicating destabilisation. The Vogel–Fulcher–Tammann (VFT) model was fitted to all datasets (RMSE < 5%). A VFT-based screening map uses two ratios at the friction test temperature: $R_{\eta }=\eta /{\eta }_{\mathrm{neat}}$ (relative film-forming tendency) and $R_s=S/S_{\mathrm{neat}}$ with $S=B/{(T-T_0)}^2$ (thermal-thinning sensitivity). A Preferred regime, $R_{\eta }\ge 1.25$ and $R_s\le 0.95$, is correlated with lower friction, smaller wear scars, and copper rating 1a, with most aged conditions migrated out of this regime. Under boundary conditions, 5–10 wt% water generally reduced friction, whereas higher fractions and ageing increased friction and wear. Synthetic oil (5W-40) showed the most robust response. Full article