Search Results (14,821)

The valorization of agricultural waste into high-value carbon nanomaterials offers dual benefits: it reduces pollution and provides low-cost materials for sustainable technologies. This work synthesizes graphene-like carbon from Ghars date waste via mild KOH-assisted pyrolysis at 1000 °C. The material (G-GhW1000) exhibits a sharp (002) XRD peak at 26.16° (d-spacing = 3.40 Å), a characteristic π → π* transition at 253 nm, and a high C/O ratio of 27.37. Dispersed in tap water (0.5 g/L) by simple hand shaking (without ultrasonication), it serves as a photothermal nanofluid in a modified single-slope solar still (MSS). Under outdoor conditions, the MSS produces 4.69 L·m⁻²·day⁻¹, which is 18.7% higher than a conventional still, with thermal efficiency rising from 27.2% to 30.8% (with a reproducible 19.0% enhancement in summer). Samples prepared at 800 °C and 900 °C give 4.0% and 6.4% lower yields, while the 1100 °C sample gives only 6.0% improvement, confirming 1000 °C as the optimal temperature. The superior performance at 1000 °C is attributed to the optimal balance between graphitization, deoxygenation, and structural integrity, as evidenced by XRD, FTIR, EDX and UV-Vis analyses. The enhanced performance is linked to higher water temperature (68 °C) and larger ΔT. The distilled water meets WHO standards (TDS 9.35 mg/L, >99.4% reduction) with no detectable graphene-like carbon carryover. This work demonstrates the potential of waste-derived graphene-like carbon as a low-cost additive for solar desalination, addressing water scarcity and waste management within a circular economy framework. To our knowledge, this is the first study to use Ghars date waste-derived graphene-like carbon in a solar still. Full article

Environmental sustainability of natural and synthetic fibers used in textiles and composites depends on their impacts throughout production, use, and end-of-life (EoL) stages. Natural fibers are renewable and biodegradable but may require substantial water and agricultural inputs, whereas synthetic fibers contribute to fossil resource depletion, microplastic pollution, and persistent waste generation. Natural fibers are often regarded as more sustainable alternatives to synthetic fiber; however, evidence from a life cycle assessment (LCA) reveals a more nuanced reality. As demand for fiber-based materials increases across textile and composite applications, a deeper understanding of the environmental implications of both natural and synthetic options becomes essential. This review compares these fiber categories from a life cycle perspective, examining carbon footprint, energy demands, resource consumption, and EoL pathways. Natural fibers such as cotton, flax, jute, hemp, sisal, banana, coir, and emerging plant-based alternatives offer advantages including biodegradability and carbon sequestration during cultivation. Nevertheless, agricultural practices and subsequent industrial processing require substantial land, water, and chemical inputs. Synthetic fibers, predominantly derived from fossil resources, provide a long service life and consistent performance but are associated with high greenhouse gas (GHG) emissions, dependence on non-renewable feedstocks, microplastic pollution, and broader environmental impacts. By presenting a comprehensive life cycle-based comparison, this review identifies the conditions under which each fiber type may offer environmental benefits, supporting informed material selection for sustainable development. Full article

Excessive nitrate discharge causes water eutrophication and public health risks, which has become a core challenge in global water environment governance. Conventional nitrogen removal technologies suffer from limitations such as carbon source dependence and secondary pollution, and can hardly meet the requirements of low-carbon water treatment. Driven by electric energy and free of additional chemical reagents, electrocatalytic nitrate reduction enables flexible regulation of product selectivity. Among all possible reaction pathways, selective N₂ production is the nitrogen removal route with the highest environmental benefits. However, constrained by the high energy barrier of N–N coupling and intense competition from side reactions, achieving highly selective N₂ production remains a major technical difficulty, and most existing reviews in this field focus on ammonia synthesis. This paper systematically reviews the research progress in this field, elucidates the reaction network and nitrogen production mechanism, compares the advantages and disadvantages of three types of selectivity evaluation methods, summarizes the design strategies of multi-scale electrocatalysts, and analyzes how operational parameters (including applied potential, electrolyte composition, pH, etc.) and reactor configuration regulate the reaction selectivity. Finally, the existing challenges are concluded and future development directions are prospected, so as to provide a reference for the research, development and engineering application of electrocatalytic nitrogen removal technology. Full article

Coastal power plants draw seawater from the open ocean through their cooling-water circulation systems. The cooling water falls over an overflow weir inside the siphon well, entraining large quantities of air, and generates a foam pollution plume upon discharge to the sea. By combining physical model experiments with numerical simulation, this study investigates the key factors governing foam stability and the aeration behavior of the water downstream of the siphon-well overflow weir. The principal conclusions are as follows: among the three single-factor variables tested in controlled laboratory conditions—temperature, salinity, and shellfish-flesh suspension concentration—the biological substance proxy showed the strongest effect on foam stability; when the shellfish-flesh suspension concentration reaches 20% (mass/volume basis, independently prepared), the foam volume and half-life increase by factors of 1.4 and 3.36, respectively, relative to the 4% baseline condition. When the dimensionless aeration depth z/z₉₀ < 0.75, the air-concentration profile rises relatively slowly with depth, whereas it increases more rapidly as the free surface is approached. Within the investigated viscosity range of 1.0–8.3 mPa·s (1.0 mPa·s for the pure-water control and 1.5–8.3 mPa·s for the measured viscosities of the 4–20% shellfish-flesh suspensions), the cross-sectional mean air concentration shows an overall decreasing trend as the liquid-phase viscosity increases, and the total bubble number density decreases correspondingly. The findings provide a laboratory-based indication of the mechanisms that must be addressed in the development of physical foam-suppression technologies; confirmation against field discharge water is required. Full article

The coal gangue waste dumps formed by open-pit coal mining are prone to low-temperature oxidation and heat storage, creating deep hidden high-temperature abnormal areas, continuously releasing toxic gases, and causing complex disasters such as slope instability and water and soil pollution. At present, self-ignition prevention and control technology is only applicable to the shallow treatment of small and flat gangue mountains. For large, deep, high-temperature waste dumps with significant height differences, multiple steps, and large areas, there is a lack of an integrated, complete set of technologies. The multi-field coupling mechanism of grouting fire extinguishing lacks engineering verification, and there is no quantitative evaluation system combining long and short periods. This paper takes the deep spontaneous-combustion high-temperature area of the No. 5 spoil dump of Lutian Coal Mine of Wuhai Energy as the research object. With the core goals of precisely delineating the fire zone space, revealing the multi-field coupling fire extinguishing mechanism of grouting, and establishing a long-term quantitative evaluation system, this study proposes a multi-process joint governance technology, along with a standardized hole filling and zoned differentiated grouting parameter system. The research systematically demonstrated technical feasibility through on-site drilling, large-scale grouting construction, and full-process quality control and error analysis. The results show that the 50 m interval geothermal gradient boreholes can accurately identify high-temperature distributions in the deep part of the dump from 0 to 34 m. The maximum combustion depth of the fourth-level and fifth-level platforms is 34 m and 20 m, respectively. A total of 1578 grouting boreholes have been constructed, with a total grouting volume of 139,289.3 cubic meters. After the treatment, the concentrations of toxic gases were all below the detection limits of the equipment, and the single cooling range reached 43% to 87%. This research refined relevant theories on the spontaneous combustion control of large-scale multi-step waste dumps, established standardized engineering processes, and provided theoretical and engineering references for the prevention and control of spontaneous combustion of solid waste in similar mines. It holds significant value for the ecological safety of mines and regional pollution control. Full article

Microplastics (MPs), defined as plastic particles smaller than 5 mm in diameter, are an emerging class of environmental contaminants of global concern. As the “Water Tower of Asia” and a critical global ecological barrier, the environmental condition of the Qinghai–Tibet Plateau has a direct influence on the ecological security of major river systems and the well-being of populations downstream. MPs have now been detected across multiple environmental compartments on the plateau, including soils, water bodies, and glaciers. Given the fragility and ecological uniqueness of the region, systematic investigation of plastic pollution here is essential for safeguarding its ecological security. Based on current research, existing data on MP pollution across the Qinghai–Tibet Plateau are reviewed and synthesized. Evidence suggests that the abundance of MP varies significantly across different environmental media in various regions and is influenced by multiple factors. Two major potential sources are identified: local anthropogenic activities and transboundary inputs via atmospheric transport and other pathways. The unique environmental conditions of the region, such as intense ultraviolet radiation, large day–night temperature variation, and frequent high-wind events, provide a distinctive setting for the migration, dispersion, transformation, and degradation of MPs across environmental matrices. Understanding the distribution, sources, and migration patterns of microplastics on the Qinghai–Tibet Plateau will help facilitate sustainable environmental management, ecosystem conservation, and pollution control in these fragile high-altitude regions. Full article

Low-cost adsorbents derived from agricultural and livestock waste offer a sustainable approach to wastewater remediation. In this study, a material derived from cow dung ash (SMCDA) was prepared through a simple waste-valorization route without chemical activation and evaluated for the removal of methylene blue (MB) from aqueous solution. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, and zeta-potential measurements were used to characterize the mineral composition, surface functional groups, morphology, pore structure, and surface charge of SMCDA. Batch adsorption experiments examined the effects of solution pH, adsorbent dosage, initial MB concentration, contact time, and temperature. The highest removal efficiency, 97.33%, was obtained at pH 8 with an SMCDA dosage of 1000 mg L⁻¹. Equilibrium data were fitted using seven isotherm models and evaluated using multiple statistical criteria and Multi-Objective Optimization by Ratio Analysis (MOORA). The Freundlich model achieved the highest MOORA ranking and predicted an equilibrium adsorption capacity of 13.944 mg g⁻¹ at the highest concentration investigated, which is close to the experimental value of 14.425 mg g⁻¹. The results are consistent with heterogeneous adsorption involving electrostatic attraction, possible π–π interactions, hydrogen bonding, and pore filling. These findings demonstrate the potential of cow dung ash as a low-cost adsorbent prepared without hazardous chemical activating agents. Full article

Nonylphenol (NP), a typical emerging pollutant, is widely detected in water bodies, yet its hepatotoxic mechanisms and mitigation strategies remain underexplored. This study evaluated the protective effects of a mixed probiotic (Lactobacillus acidophilus and Bacillus subtilis) against NP-induced hepatotoxicity in Silurus meridionalis by integrating transcriptomic and metabolomic analyses, with validation by RT-qPCR and ELISA. The results showed that NP exposure disrupted the arachidonic acid (AA) pathway (activating pro-inflammatory COX and LOX pathways while the suppressing anti-inflammatory CYP450 branch), promoted ferroptosis via iron dyshomeostasis and oxidative damage, and impaired triglyceride (TG) synthesis. Probiotic pretreatment reversed these toxic effects by modulating AA metabolism, suppressing COX (ptgs2a↓ → PGE₂↓) and LOX (alox12↓ → MDA↓) pathways, while upregulating the CYP450 pathway (cyp2j↑ → 11,12-EET↑). Probiotics also enhanced Fe³⁺ sequestration (steap4↑) and antioxidant defense (CAT↑, gpx4a↑), limiting Fenton reaction-mediated oxidative injury, and restored hepatic TG synthesis through upregulation of the DHAP-to-TG cascade (DHAP—(gpd1b↑) → G3P↑—(gpat3↑) → LPA—(agpat6↑) → PA—(plpp7↑) → DAG↑—(dgat2↑) → TG↑). These findings suggest that NP induces hepatotoxicity in S. meridionalis, involving ferroptosis, AA metabolism disruption and impaired TG synthesis as interconnected pathological events. Probiotics likely counteract this toxicity through systemic metabolic reprogramming. Collectively, these findings elucidate the hepatotoxic mechanisms of NP in S. meridionalis and offer toxicological data for its risk assessment, supporting the potential of probiotic-based strategies to mitigate emerging pollutant impacts in aquatic organisms. Full article

Heavy metal wastewater, characterized by high toxicity, poor biodegradability, and strong bioaccumulation potential, poses a serious threat to the ecological environment and human health. Conventional chemical treatment methods are costly and prone to secondary pollution. In contrast, using solid waste to prepare environmental functional materials for “waste control by waste” has emerged as a research hotspot in the field of synergistic water pollution control and resource recovery. This review systematically consolidates the sources, physicochemical properties, and compositional characteristics of typical industrial solid wastes—including red mud, electroplating sludge, fly ash, copper slag, and blast furnace slag—and elucidates how compositional variations constrain the selection of functionalization pathways. On this basis, key preparation techniques, namely hydrothermal synthesis, surface modification/impregnation, thermal treatment, geopolymerization, and sol–gel/polymerization, are critically reviewed and compared in terms of product structural regulation, process complexity, and engineering scale-up potential. Subsequently, the adsorption performance of the resultant materials toward heavy metals such as Pb²⁺, Cu²⁺, Cr(VI), As(VI), Cd²⁺, Ni^2+, and Zn²⁺ is discussed, with particular emphasis on the pronounced effects of pH, temperature, initial concentration, coexisting ions, and adsorbent dosage on adsorption capacity. Notably, Pb²⁺ exhibits the highest adsorption capacity, whereas the removal of Cr(VI) and As(V) is strongly governed by the positive charge density and reduction efficiency of the material surface. In quinary heavy metal competitive systems, marked differences in the affinity of adsorption sites toward distinct metal ions have been observed. Mechanistic analysis identifies ion exchange, surface complexation, electrostatic attraction, and redox reactions as the predominant removal pathways. This review further incorporates engineering-oriented assessments, including multi-component competitive adsorption, fixed-bed column operation, and regeneration stability, and identifies the critical bottlenecks currently impeding the transition from laboratory-scale research to practical implementation—namely, performance instability arising from feedstock variability, attenuation of adsorption capacity during prolonged operation (with a 10–40% decline over 5–10 cycles), underdeveloped regeneration and recovery routes, and a systemic deficiency in techno-economic analysis and life-cycle assessment data. Finally, future research directions are proposed, emphasizing the development of low-carbon and energy-efficient preparation technologies, the promotion of synergistic valorization of multiple solid wastes alongside critical metal recovery, and the advancement of this field toward engineering applications through artificial intelligence-assisted design and life-cycle assessment, thereby furnishing theoretical references and technical support for the integrated management of industrial solid waste resource utilization and heavy metal wastewater treatment. Full article

The contamination of water bodies with organic pollutants has emerged as one of the most pressing environmental and public health challenges of the modern era. The continuous discharge of dyes, pesticides, agricultural runoff, and pharmaceutical residues into the aquatic ecosystem degrades water quality. Long-term exposure to these organic pollutants poses a severe risk to human and aquatic life. ZnO and TiO₂ have emerged as promising photocatalysts, particularly for degrading organic waste in wastewater. However, their photocatalytic activity is limited to the UV region due to their wide band gaps. To improve nanoparticle efficiency, polydopamine (PDA) is incorporated as a modifying agent. PDA-modified ZnO and TiO₂ nanocomposites exhibit enhanced photocatalytic activity in the degradation of various organic pollutants under visible light, compared with their unmodified counterparts. Furthermore, they exhibit improved antibacterial activity against a variety of waterborne pathogens; this is advantageous as wastewater contains both chemical pollutants and microorganisms. Thus, the combined photocatalytic and antibacterial properties of PDA-modified ZnO and TiO₂ make them promising materials for next-generation wastewater treatment. Full article

This study evaluates whether existing long-term monitoring data are sufficient to distinguish natural background concentrations from anthropogenic influences on chemical river water quality in Lake Sevan basin. A comprehensive dataset covering physicochemical parameters, nutrients, and trace metals was analyzed for nine major tributaries with different geological settings and land-use characteristics. Multivariate statistical analysis was applied to identify baseline conditions and deviations attributable to human activities. The results indicate that water chemistry is primarily controlled by lithology and hydrological regime, particularly in minimally impacted headwater regions. In contrast, elevated concentrations of nutrients (e.g., nitrate and phosphate) and selected trace elements were associated with agricultural runoff, urban discharge, and localized industrial inputs. Spatial patterns reveal clear gradients of increasing anthropogenic impact downstream and in densely populated sub-basins. The study also demonstrates that, while the current monitoring network is suitable for assessing the overall chemical status of rivers, it is less effective in defining natural background levels and quantifying individual pollution sources due to limited upstream reference conditions. Overall, this approach provides a scientific basis for improved water quality management and policy implementation in the Lake Sevan basin. The findings highlight the importance of integrating long-term monitoring data with statistical tools to support sustainable watershed management in vulnerable catchments. Full article

Microplastics are plastic particles smaller than 5 mm that have become a growing environmental concern due to their persistence and widespread distribution. They originate from diverse sources, including laundry detergents, vehicle tires, cosmetic microbeads, and the degradation of larger plastics through ultraviolet radiation and saline exposure. This systematic review was conducted following the PRISMA guidelines to summarize current knowledge on the environmental and human health effects of microplastics. A comprehensive literature search was performed in ScienceDirect, PubMed, Web of Science, and Google Scholar databases, yielding 2694 initial records. After applying exclusion criteria and removing duplicates, 111 studies were selected for full reading, and 54 articles were ultimately included in the analysis. The results reveal that microplastics can absorb and release pollutants, leading to the contamination of water and soil and enabling them to enter the food chain, thereby posing potential risks to both ecosystems and human health. However, significant discrepancies were found among the databases regarding the amount and quality of available data, highlighting the need for standardized research approaches. In conclusion, understanding the sources, distribution, and impacts of microplastics is crucial to developing strategies to mitigate their release, and further research is essential to assess their long-term effects and to guide environmental policy. Full article

Estimating transmissivity and hydraulic conductivity is crucial for groundwater resource assessment, flow modeling, pollution remediation, and sustainability studies. In the volcanic highlands of Ethiopia, millions rely on hand-dug wells and springs for drinking and irrigation, yet the hydraulic properties of these shallow aquifers remain largely uncharacterized. This study provides the first comprehensive estimation of transmissivity and hydraulic conductivity for the shallow groundwater aquifers in the Lake Tana Basin through integrated analyses of pumping and slug tests. The effective dataset comprised 31 tests, unevenly distributed among four aquifer types: eight in Quaternary basalt, 13 in weathered basalt regolith, seven in pyroclastic deposits, and three in alluvio-lacustrine sediments. Time-series groundwater level data were additionally used to characterize seasonal recharge responses and recession behaviors. Quaternary basalt aquifers showed high transmissivity values of 117–1064 m²/d, with a geometric mean of 235 m²/d, reflecting the influence of open and hydraulically connected fractures. Weathered basalt regolith aquifers had transmissivity values of 0.27–71 m²/d, with a geometric mean of 3.09 m²/d, whereas pyroclastic aquifers ranged from 0.17 to 11 m²/d, with a geometric mean of 0.96 m²/d. The alluvio-lacustrine aquifers ranged from 1.68 to 173 m/d, with a geometric mean of 8.56 m²/d; however, this estimate should be interpreted cautiously because it is based on only three tests. This study reveals strong heterogeneity within and across aquifers. Pumping tests were generally more applicable to the relatively transmissive Quaternary basalt aquifers, whereas slug tests provided a practical approach for characterizing shallow weathered regolith, pyroclastic, and alluvio-lacustrine aquifers. Seasonal groundwater level patterns varied with geology and topographic position: aquifers on slopes and plateaus generally showed rapid recharge and recession responses, whereas those at foothills and floodplains exhibited more sustained groundwater levels, probably because of lateral inflow and interactions with river water. The findings provide preliminary hydraulic-property ranges for groundwater assessment and indicate that fractured Quaternary basalt aquifers may represent promising targets for water-supply development. Full article

Caffeine has been recognized as an emerging pollutant in aquatic ecosystems due to its persistence. This study evaluated the techno-economic viability of caffeine removal using thermally modified bentonite (Na–Bent–400) as an adsorbent. Caffeine removal was simulated under two operational schemes: Scenario 1 (S1: Adsorption–Disposal), where Na–Bent–400 is discarded following saturation, and Scenario 2 (S2: Regeneration–Reuse–Disposal), which integrates adsorbent regeneration to enable the reuse of Na–Bent–400 in a second adsorption before final disposal. Using the optimized model for caffeine removal (95.97% removal efficiency in batch operation: 2.26 g/L Na–Bent–400, 30 mg/L caffeine, and pH 8), the process was scaled up through process simulation in Aspen Plus (V14) for a treatment flow rate of 8 L/s (252,288 m³/year). Capital expenditure (CapEx) was estimated at USD 331,004 without adsorbent regeneration (S1) and USD 486,725 with regeneration (S2), showing a 47% increase due to auxiliary equipment and operational complexity; however, integrating adsorbent regeneration minimizes long-term operational expenditures by reducing raw material requirements and wastewater treatment costs. Estimated water treatment costs based on operational expenditures (OpEx) are USD 1.38/m³ for S1 and USD 0.74/m³ for S2. A sensitivity study found that caffeine concentrations above 30 mg/L have little effect on treatment costs. By evaluating these scenarios, this study demonstrates the preliminary techno-economic viability of thermally modified bentonite for treating caffeine-contaminated agroindustry effluents. Full article

Hollow fiber loose nanofiltration (HF-LNF) has attracted increasing attention as a pressure-driven membrane platform that combines loose nanofiltration (LNF) selectivity with the high packing density and self-supporting geometry of hollow fibers. This review critically evaluates recent advances in HF-LNF membranes, including controllable fabrication strategies, surface functionalization techniques, and practical engineering applications, with a discussion of life cycle assessment (LCA) for evaluating the environmental and economic sustainability of HF membrane systems. Phase inversion, interfacial polymerization (IP), coating, and grafting are compared in terms of structural controllability, process complexity, selective-layer stability, modification uniformity, reproducibility, and scale-up feasibility. Phase inversion is relatively compatible with continuous hollow-fiber spinning, but independent regulation of the support and selective layer remains difficult. IP provides greater control over selective-layer chemistry and effective pore size, whereas coating and grafting offer flexible surface functionalization but may be limited by additional transport resistance, layer durability, and non-uniform modification of curved surfaces. Direct HF-LNF application remains concentrated on dye/salt separation. Based on the evidence from HF-NF or flat LNF systems, the potential of HF-LNF in water softening, heavy metal removal and emerging pollutant control is analyzed. Critical challenges restricting industrial translation are discussed, including poor long-term antifouling capacity and difficulties in large-scale, low-cost manufacturing. On this basis, LCA is further introduced as a decision-support framework for identifying potential environmental hotspots in membrane manufacturing and operation, while the limited availability and comparability of HF-LNF-specific life-cycle data are explicitly recognized. Ultimately, it is proposed to focus on novel functional materials, eco-friendly preparation processes, and scaled membrane engineering, aiming to offer theoretical support for the rational design and real-world industrial deployment of next-generation HF-LNF membranes. Full article