Search Results (41,681)

The transition from conventional silica nanoparticle (SiNP) production based on purified alkoxysilanes and high-temperature flame hydrolysis of silicon tetrachloride to renewable and waste-derived silicon resources requires more than precursor substitution. It requires a mechanistic understanding of how feedstock mineralogy, silicon speciation, impurity chemistry, and processing history propagate through dissolution, nucleation, condensation, gelation, aging, drying, and pore evolution to determine material performance, environmental burden, and manufacturing feasibility. Although previous reviews have established the technical feasibility of producing silica from secondary resources, their predominant organization by feedstock, synthesis route, or application provides limited ability to explain why nominally similar processes generate materials with markedly different structural and functional properties. This review addresses these through a resource-pull, feedstock-to-function framework that links resource chemistry and process design to critical material attributes, application-specific specifications, sustainability, and scale-up requirements. Agricultural residues, industrial by-products, geothermal resources, waste glass, and fluorosilicate streams are critically compared according to silicon form and phase, reactivity, impurity profile, compositional variability, purification demand, and attainable product quality. Particular attention is given to waste-derived alkaline silicate systems, in which molecular, oligomeric, and colloidal silica coexist and therefore require characterization beyond bulk SiO₂ concentration. Established and emerging processing strategies, including controlled combustion and alkaline extraction, alkali fusion, ambient-pressure drying, microwave and mechanochemical activation, biogenic and biomimetic templating, and continuous processing, are evaluated according to their mechanistic effects, technological maturity, structural control, and demands for energy, reagents, water, solvents, effluent treatment, and capital. Across these routes, gelation and aging emerge as critical transfer stages through which feedstock composition is translated into network connectivity, pore architecture, shrinkage behavior, and ultimately functional performance. Evidence from secondary-source aerogels further shows that properly controlled waste-derived systems can attain BET surface areas of approximately 350–500 m² g⁻¹, within the textural range of many alkoxide-derived materials, indicating that feedstock variability, impurity management, and process control are more important constraints than an inherently lower performance ceiling. On this basis, this review proposes a minimum evidence framework comprising feedstock traceability, intermediate-speciation and colloidal characterization, silicon mass balance, gelation and aging metrics, application-specific qualification criteria, performance-normalized life cycle and techno-economic assessment, process analytical control, and staged pilot validation. Collectively, these principles provide a mechanistically grounded basis for moving sustainable silica synthesis beyond isolated proof-of-concept demonstrations toward reproducible, scalable, application-matched, and commercially credible manufacturing platforms. Full article

The Hwange Mining Area, located in the Mid-Zambezi Karoo Basin in northwestern Zimbabwe, is a major centre for coal mining, processing, and thermal power generation. This study evaluates the ecological and public health risks associated with these activities by characterising radionuclide (²²⁶Ra, ²³²Th, ⁴⁰K) activity concentrations in coal and surrounding soils using Hyper-Pure Germanium (HPGe) gamma spectrometry. Samples were collected from four locations, as follows: Hwange Colliery Company (underground and open-cast mines), Zambezi Gas open-cast operations, residential areas, and the Zimbabwe Power Company (ZPC) thermal power station. Radionuclide concentrations were measured using Hyper-Pure Germanium (HPGe) gamma spectrometry. Mean activity concentrations in coal were low at both mining sites (Hwange Colliery: ²²⁶Ra 16 ± 5.3 Bq/kg), ²³²Th 14 ± 5.7 Bq/kg), (⁴⁰K 51 ± 8.8 Bq/kg) and Zambezi Gas (²²⁶Ra 9.80 ± 2.3 Bq/kg), ²³²Th (11 ± 3.3 Bq/kg), ⁴⁰K (43 ± 26 Bq/kg), well below UNSCEAR world coal averages. In contrast, soils from residential areas): ²²⁶Ra (36 ± 15 Bq/kg), ²³²Th (36 ± 12 Bq/kg) and ⁴⁰K (220 ± 80 Bq/kg), and the ZPC power station (²²⁶Ra 47 ± 8.6 Bq/kg, ²³²Th (42 ± 10 Bq/kg), and ⁴⁰K 230 ± 92 Bq/kg, showed markedly elevated concentrations, consistent with the accumulation of coal-combustion by-products such as fly ash. Radiological hazard indices remained within internationally accepted limits at all sites, as follows: radium equivalent (Raeq) ranged from 29 ± 6.7 Bq/kg (Zambezi Gas) to 120 ± 18 Bq/kg (ZPC), well below the 370 Bq/kg safety ceiling, while external and internal hazard indices (H_ex, H_in) remained below unity throughout, peaking at 0.32 and 0.46, respectively, at ZPC. Annual effective dose equivalents (AEDE) ranged from 16 ± 3.8 to 69 ± 10 μSv/year, the latter (ZPC) representing approximately 7% of the ICRP public dose limit of 1 mSv/year. Excess lifetime cancer risk (ELCR) values ranged from 5.56 × 10⁻⁵ (Zambezi Gas) to 2.42 × 10⁻⁴ (ZPC), remaining below the global average outdoor reference of 0.29 × 10⁻³ but reaching approximately 83% of this reference at ZPC and 71% in residential areas. These findings indicate that, while coal mining activities in Hwange contribute minimally to environmental radioactivity, coal combustion at the ZPC thermal power station is the dominant driver of elevated radionuclide concentrations and radiological indices in the surrounding environment, with residential soils reflecting the same enrichment pathway. Although no immediate radiological hazard was identified at any location, the comparatively higher indices at ZPC and in nearby residential areas underscore the need for continuous environmental monitoring, strengthened regulatory control, and targeted radiation protection strategies to safeguard workers and nearby communities. Full article

Background: Airborne microplastics (AMPs) are an emerging air pollutant and there are growing concerns about their potential effects on respiratory health due to their persistence, inhalability and ability to carry other toxic pollutants. Methods: Relevant peer-reviewed studies released from 2015 to 2025 were located by searches on PubMed, Scopus, and Web of Science. Data from experimental, epidemiological, and review research were amalgamated to investigate sources of airborne microplastics, routes of exposure, analytical methodologies, respiratory toxicological processes, and regulatory viewpoints. Results: Modern studies suggest inhaled antimicrobic peptides can reach the lower respiratory tract and cause chronic pulmonary inflammation via induction of oxidative stress, mitochondrial dysfunction, epithelial barrier damage, inflammasome activation, immune system imbalance and extracellular matrix remodeling. These pathways have been associated with chronic respiratory diseases, such as chronic obstructive pulmonary disease, asthma, pulmonary fibrosis, and lung carcinoma. Toxicity can be increased by the accumulation of heavy metals, persistent organic pollutants and microbiological impurities. However, the lack of standardised protocols for exposure assessment, inconsistency of sampling and analytical methods and limited human epidemiological data hamper health risk assessment. Conclusions: Airborne microplastics are an emerging environmental health concern with potentially significant effects on respiratory health. Harmonised surveillance strategies, standardised analytical methods, improved inhalation exposure models and prolonged epidemiological studies are urgently needed to improve risk assessment and enable evidence-based air quality policy for the protection of respiratory health. Full article

Global commodity chains reshape rural territories through interconnected environmental and socioeconomic processes; these dynamics are often examined through the lens of land-use change. Export-oriented agricultural frontiers illustrate how global market integration can generate landscape and societal transformations. In western Mexico, the expansion of the avocado industry exemplifies commodity-driven territorial change, linking land-use dynamics with transformations in rural economies and livelihoods. This study analyzes how export integration into the international avocado commodity chain was associated with transformations in land systems and socioeconomic dynamics across four municipalities in Michoacán, Mexico, between 2003 and 2023. Using high-resolution land-use maps alongside demographic and socioeconomic indicators, we apply a qualitative, comparative and inductive synthesis of spatial and census data to examine how commodity integration interacted with local conditions to shape landscape and territorial organization. Avocado expansion coincided with territorial transformation, including the conversion of pine-oak forest and traditional agricultural lands, as well as changes in labor arrangements, demographic dynamics, and rural livelihood systems. Land-use analysis shows continued orchard expansion and accelerated land conversion after 2015. Socioeconomic indicators reveal population growth, increased female employment, and persistent income inequality, highlighting the uneven incorporation of rural territories into global commodity chains. We identified four territorial pathways: agricultural specialization, agro-industrial urbanization, transitional diversification, and rural commodity integration. These findings contribute to debates on uneven geographical development and commodity frontier expansion by showing how global commodity integration intersects with ecological, economic, and social processes to generate distinct pathways. Full article

The textile dyeing and printing (TDP) industry in Zhejiang Province faces significant pressure to reduce conventional pollutants and carbon emissions. Dyeing and finishing (DF) are key links in energy consumption and pollutant emissions in the TDP industry. However, the trade-offs between pollution reduction and carbon mitigation remain poorly understood. This study evaluated five synergistic technology pathways using a hybrid life cycle assessment (LCA) approach. The pathways included low-carbon energy substitution, waste heat recovery, advanced wastewater treatment, intelligent process control, and integrated application. The IMPACT 2002+ method was used to quantify 7 environmental impact categories. The results showed that no single technology pathway achieved optimal performance across all categories. Scenario 3 (advanced wastewater treatment) reduced eutrophication potential by 54.97% but increased global warming potential by 18.00%. Scenario 5 (integrated application) achieved the best overall performance. It reduced non-renewable energy consumption by 30.90%, global warming potential by 32.69%, acidification potential by 26.08%, and eutrophication potential by 40.00%. The synergy coefficient of Scenario 5 was 1.08, indicating strong pollution-reduction synergy. Extrapolation to the provincial level showed reductions of 40% for COD, 39.76% for ammonia nitrogen, 40.78% for SO₂, 10.67% for NOx, and 14% for VOCs. These findings demonstrate that systematic technology integration can resolve the trade-offs inherent in individual pollution control measures under the conditions evaluated in this Zhejiang-based case study. This study provides scientific guidance for technology selection and policy formulation in the DF industry. Full article

Construction on very soft peaty clay remains a major geotechnical challenge due to its high compressibility and low-bearing capacity. The deep mixing method (DMM) is widely adopted for in situ stabilization using cement; however, environmental concerns associated with cement production have driven the search for sustainable alternatives such as geopolymers using low-carbon materials. Existing studies predominantly rely on dried peat, processed precursors such as fly ash or calcined ground rice husk ash (RHA), and high concentrations of alkali activators such as sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH), which increase both environmental and economic burdens. This study develops a novel waste-based geopolymer incorporating untreated brick kiln-derived RHA, activated solely with low-concentration NaOH, while completely eliminating Na₂SiO₃. The avoidance of precursor pre-treatment and Na₂SiO₃ significantly reduces processing energy, cost, and associated environmental emissions. A systematic investigation was conducted to determine the optimum mixing time for maximizing strength under field-relevant conditions. Mechanical performance was evaluated using unconfined compressive strength tests considering variations in binder content, curing duration (7, 28 days), alkali concentration (6, 3 M), and alkali-to-binder ratio (0.3, 0.5, 0.7). Failure characteristics were examined, and an integrated framework combining cost analysis, life cycle assessment, and grey relation analysis was employed to optimize mix design. The optimized geopolymer achieved 2.2 times higher strength than cement-treated soil, with 25% cost reduction and more than 85% reduction in environmental impact. These findings demonstrate a scalable and sustainable solution for stabilizing highly organic soils, while promoting the valorization of supplementary cementitious materials without energy-intensive preprocessing. Full article

With the improvement in people’s quality of life, issues related to food health and nutritional supplementation have attracted widespread attention. Polyphenols have been established as bioactive compounds that exert multiple beneficial effects on human health. However, due to their chemical instability and susceptibility to environmental factors, polyphenols face restrictions during food processing and exhibit decreased absorption rates in the human body. This review critically investigates the encapsulation of polyphenols via nanoparticle technology, with emphasis on preparation methodologies, mechanistic pathways, and application performance, particularly with respect to oxidative stability in oil-based systems. The present review provides a comprehensive discussion on the influence of nanoparticle encapsulation on the bioaccessibility of polyphenols, with the goal of enhancing their bioaccessibility and broadening their applicability across the food, cosmetic, and pharmaceutical sectors. These findings offer significant reference value for the future incorporation of polyphenols into food matrices. Full article

Sustainable livestock production in the arid regions of Central Asia depends almost entirely on groundwater resources. However, regional groundwater quality remains insufficiently characterized from the perspective of long-term water security and sustainable pasture management. Understanding the interaction between natural hydrogeochemical evolution and anthropogenic contamination is therefore essential for developing climate-resilient groundwater management strategies. This study presents a comparative hydrogeochemical assessment based on 101 groundwater samples collected from 58 sites in the Karaganda region and 43 sites in the Ulytau region during a single dry-season campaign (June–July 2025), with field sampling conducted across 4630 km² of active pastureland within a combined regional area of 409,070 km². Groundwater in Ulytau showed substantially greater mineralization, with a median TDS of 1027 mg/L compared with 538 mg/L in Karaganda; the proportion of samples exceeding 1000 mg/L was 53.5% (23/43) and 29.3% (17/58), respectively (Fisher’s exact p = 0.023). Median NO₃⁻ concentrations were also markedly higher in Ulytau (35.0 mg/L) than in Karaganda (5.0 mg/L), with the 50 mg/L guideline exceeded in 46.5% (20/43) vs. 19.0% (11/58) of samples (p = 0.004). NO₃⁻ and TDS were not significantly correlated in Karaganda (r_s = 0.108, p = 0.418), whereas a moderate positive relationship occurred in Ulytau (r_s = 0.388, p = 0.010). These results indicate that regional salinization is predominantly controlled by geogenic hydrochemical evolution, while nitrate contamination represents a localized anthropogenic pressure associated with vulnerable water points. The pronounced quantitative contrast between the two regions highlights the need for region-specific groundwater protection and management strategies to support sustainable livestock production and long-term water security in Central Kazakhstan. Rather than providing only a regional hydrochemical description, the present study evaluates groundwater quality as a sustainability indicator for livestock production, groundwater security, and regional adaptation to increasing water stress. Groundwater quality differed significantly between the two regions, with Ulytau exhibiting consistently higher mineralization, more frequent nitrate exceedances, and higher groundwater vulnerability. Statistical analyses confirmed that groundwater quality deterioration is controlled by different combinations of geogenic processes and localized anthropogenic impacts in the two hydrogeological settings. The findings demonstrate that groundwater quality represents a critical component of sustainable livestock production in Central Kazakhstan. The proposed regional groundwater vulnerability framework provides practical guidance for groundwater protection, climate adaptation, and the sustainable management of pastoral water resources under increasing environmental pressures. Full article

Wind erosion is a major driver of land degradation in drylands worldwide, yet the relative importance of climatic forcing and local surface conditions remains poorly understood. We quantified horizontal mass transport (HMT), characterized the particle-size distribution and organic matter of transported sediments, and identified the main environmental controls on wind erosion across three rangeland sites in the Patagonian steppe of southern Argentina. HMT was monitored over one year using passive sediment collectors (Mendeźs trap), while climatic erosivity, vegetation cover, and topsoil properties were concurrently assessed. Wind erosion exhibited substantial spatial variability, with annual HMT ranging from 0.22 to 2.35 kg m⁻¹ yr⁻¹ among sites. Transported sediments were enriched in both silt and organic matter relative to source soils, indicating the preferential export of fine, carbon-rich fractions during aeolian transport. Multivariate analyses revealed that wind erosion was more strongly associated with local vegetation cover and soil erodibility than with climatic erosivity. These findings suggest that surface conditions can override regional climatic controls on sediment transport in arid rangelands. Our results highlight the critical role of maintaining vegetation cover and soil surface stability to mitigate desertification processes and provide empirical evidence to improve wind erosion assessment and land management strategies in drylands. Full article

Hydrological methods are widely used for environmental-flow assessment in data-limited rivers, but different methods often produce divergent monthly thresholds, making method selection difficult under strong seasonal variability. This study develops a scenario-based multi-objective framework for selecting hydrological environmental-flow methods in the upper Datong River, a cold-region and semi-arid headwater tributary of the upper Yellow River. Using daily discharge records from the Gadatan hydrological station during 1956–2022, monthly environmental-flow thresholds were estimated using nine commonly applied hydrological methods. A four-dimensional RDVS framework was constructed to evaluate reliability, deficit intensity, naturalness deviation, and intra-annual rhythm distance. Pareto non-dominated screening and scenario-oriented ranking were then applied under three management scenarios: low-flow baseline protection, critical-period protection, and annual process consistency. The results show that low-flow months exhibit higher empirical variability and greater kurtosis and are associated with greater inter-method divergence. The Tennant method ranked first under the low-flow baseline scenario, whereas the intra-annual distribution method ranked first under both the critical-period and annual-consistency scenarios. The Texas method consistently entered the top three across all scenarios, indicating cross-scenario robustness. The targeted anomaly test and the annual-block bootstrap both supported the stability of the primary recommendations: the Tennant method ranked first in 94.0% of the S1 bootstrap replicates, whereas the intra-annual distribution method ranked first in 98.7% and 100.0% of the S2 and S3 replicates, respectively. Overall, the proposed framework transforms hydrological method comparison into a transparent, scenario-based, and reproducible selection process and provides a hydrology-based decision-support tool for screening candidate environmental-flow methods in data-limited rivers. Full article

Magnesium oxychloride (MOA) adhesive plywood represents a novel inorganic matrix panel technology that eliminates organic volatile compounds from the adhesive system and avoids high-temperature hot pressing, potentially offering significant carbon footprint advantages. This study presents a comparative life cycle carbon footprint assessment of conventional urea–formaldehyde (UF) plywood and MOA plywood manufactured in China, using 1 m³ of a finished panel as the functional unit under a cradle-to-grave system boundary, comprising the production stage (Modules A1–A3)—explicitly including forestry operations (silviculture, felling, extraction/forwarding, loading and log haulage) and veneer manufacture within Module A1, now reported as a disaggregated inventory and delimited in a system boundary diagram—and the end-of-life stage (Modules C2–C4), evaluated across three end-of-life (EOL) scenarios: incineration, landfill, and mechanical recycling. Foreground data (process energy, adhesive formulation, transport distances) are metered/primary data collected over a full production year at a single large-scale plywood plant in Suqian, Jiangsu; background data are from ecoinvent v3.9.1 (cut-off), characterised with IPCC AR6 GWP100. Results indicate that MOA plywood generates approximately 253 kg CO₂-e/m³ at the production stage (A1–A3), compared with 301 kg CO₂-e/m³ for UF plywood, a reduction of 15.8% (47.5 kg CO₂-e/m³). Contribution analysis attributes virtually the entire gap to process energy (steam 65.7%, electricity 34.3%), while adhesive raw materials and inbound transport cancel to within rounding, demonstrating that the advantage is a process energy rather than a green chemistry phenomenon. A parameter-specific one-at-a-time analysis and a 200,000-run Monte Carlo simulation with triangular distributions show no reversal of the UF–MOA ranking in any of the 200,000 realisations within the adopted uncertainty ranges, with an approximately 56 kg CO₂-e/m³ median advantage (5th–95th percentile of about 31–85). Under EOL incineration, MOA plywood retains a substantial advantage even after the newly quantified burden of flue gas HCl neutralisation (13.3 kg CO₂-e/m³) and inorganic residue management (0.9 kg CO₂-e/m³) arising from the chloride content of the Sorel cement binder are charged to the MOA system. Under landfill, both products behave similarly, as wood carbon dynamics dominate. A break-even analysis shows that the service life of MOA plywood would have to fall below 25.3 years (against a 30-year reference) for its cradle-to-gate advantage to be erased. These findings clarify the lifecycle trade-offs of inorganic adhesive plywood and provide actionable data for environmental product declarations and procurement frameworks. Full article

Excess fluoride originating from phosphate mining activities poses a significant environmental and public health challenge, particularly in arid and semi-arid regions where water resources are limited. This study presents a comparative evaluation of four conventional defluoridation technologies for the treatment of real phosphate mine waters collected from two major Moroccan phosphate mining sites (Youssoufia and Khouribga). The investigated processes included coagulation–flocculation using aluminum sulfate and ferric chloride, chemical precipitation with calcium hydroxide and calcium chloride, adsorption on aluminum oxide (Al₂O₃) and zirconium oxide (ZrO₂), and fluoride removal using calcined bovine bone apatite under both batch and continuous-flow conditions. Adsorption equilibrium was interpreted using Langmuir and Freundlich isotherm models, while the effects of adsorbent dosage, contact time, and water matrix composition were systematically investigated. Among the coagulation processes, aluminum sulfate achieved fluoride removal of up to approximately 82.5% in phosphate washing water and approximately 76.3% in mine drainage water, whereas ferric chloride removed about 52% of the dissolved fluoride under the reported conditions. Lime and calcium chloride exhibited moderate removal efficiencies of 66% and 61%, respectively. Aluminum oxide showed the highest equilibrium adsorption capacity (q_m = 7.14 mg g⁻¹), while zirconium oxide displayed faster fluoride uptake because of its higher surface affinity for fluoride ions. The presence of competing ions in real mine waters was associated with lower adsorption performance compared with synthetic fluoride solutions. Calcined bone apatite proved to be the most effective material, achieving approximately 83% fluoride removal within 20 min under batch conditions and maintaining good performance during continuous fixed-bed operation, producing treated water with fluoride concentrations below the World Health Organization guideline value. Overall, the results demonstrate that calcined bone apatite provides the highest fluoride-removal performance among the investigated materials under the tested conditions. Its waste-derived origin, rapid adsorption kinetics, and effective fluoride removal make it a promising material for the treatment of fluoride-rich phosphate mine waters. The comparative evaluation further indicates that integrating chemical pretreatment with adsorption may represent a promising strategy for the treatment and potential reuse of mining effluents, although the performance of such a combined treatment train should be validated experimentally. Full article

Bacterial communication or quorum sensing (QS) is a common yet complex system where multiple factors influence the extent to how this chemical dialog is transferred from a single clone to the larger community of microbes in the population. More often, when bacteria are in large concentrations, their genetic and subsequent biochemical response to different chemical cues is influenced by not only which microorganisms are present but also the environmental variables that surround those individuals. This is especially relevant when symbiotic bacteria are dependent upon host functions yet are in high enough concentrations that can manifest their own behaviors in response to the present host prior, during, and after colonization. This review will examine the various abiotic and biotic factors that regulate QS when bacteria are in the process of detecting, colonizing, and persisting in a host that uptakes its microbial partner from the environment, as well as the consequences of multiple stressors on this dynamic communication process. Full article

Environmental conditions have become more unstable; therefore, innovative and eco-friendly methods of food production are urgently required. Most existing hydroponic systems lack the capacity for real-time responses and decision-making based on integrated data, similar to contemporary farms. This document outlines the creation of an advanced hydroponic farming system that utilizes Internet of Things (IoT) sensors and a digital twin (DT) simulator to address these challenges. A completely monitored and continuously assessed hydroponic farming simulator operating on a Raspberry Pi, employing various sensors, data management and processing, and automated environmental regulation. The development of this intelligent hydroponic farming system employs a dual-model machine learning pipeline: one that identifies plant diseases through image analysis, and another that assesses plant nutrient levels based on sensor data. The data from the two models are combined using a cloud-based DT, enabling remote access to the DT and offering closed-loop control for irrigation, nutrient dosing, and management of all environmental factors related to crop growth in a hydroponic setting. This research showcases the capability to develop scalable, data-focused precision agriculture solutions that can adapt to the demands of today’s agricultural environment by combining all elements of IoT sensing, machine learning, and DT simulations into one functional hyperphysical system. Full article

Benzaldehyde is a key intermediate in the fine chemical, pharmaceutical, fragrance, and agrochemical industries, and the development of efficient and sustainable synthetic routes remains a major research priority. This review critically examines the principal catalytic pathways reported for benzaldehyde production, with particular emphasis on the oxidation of benzyl alcohol and the partial oxidation of toluene. Reaction conditions, catalytic systems, and performance descriptors such as conversion and selectivity are systematically analyzed, highlighting the strengths and limitations of each approach. Special attention is given to the choice of oxidants, reaction phase, and operating temperature, as these factors strongly influence process efficiency and product distribution. From a sustainability perspective, conventional routes are compared with greener alternatives based on molecular oxygen or air, aiming to reduce energy consumption and the generation of hazardous by-products. The review further discusses current challenges associated with catalyst stability, overoxidation, and process scalability. It identifies the principal scientific gaps limiting the industrial implementation of heterogeneous catalytic systems and critically examines how catalyst design, synthesis methodologies, sustainable feedstocks, waste-derived materials, and techno-economic considerations can collectively contribute to scalable and environmentally responsible benzaldehyde production. Finally, future research directions are proposed to guide the development of highly selective, economically viable, and sustainable catalytic processes. Full article