Search Results (848)

Building facades and construction materials are continuously exposed to airborne particulate matter, organic pollutants, and microbial colonization, which cause progressive soiling, aesthetic degradation, and structural deterioration while imposing high maintenance and energy burdens. Photocatalytic titanium dioxide (TiO₂) has emerged as the most widely studied material for imparting self-cleaning functionality to building surfaces, owing to its ability to mineralize adsorbed contaminants under solar irradiation and to modulate surface wettability. This narrative review provides a structured account of TiO₂-based self-cleaning coatings for building materials, organized around three complementary themes: surface mechanisms, performance metrics, and outdoor durability. We first rationalize the two intertwined self-cleaning mechanisms—photocatalytic oxidative degradation and photoinduced superhydrophilicity—and their combination with physically repellent (superhydrophobic/superamphiphobic) wetting states. We then survey the principal coating-design strategies, including morphology and facet engineering, SiO₂-TiO₂ composites, metal/non-metal doping and heterojunction construction for visible-light activation, and dual-functional photocatalytic–superhydrophobic systems, and their integration into cementitious substrates, natural stone and cultural heritage, and transparent glass/photovoltaic surfaces. The quantitative metrics used to benchmark self-cleaning performance—water contact angle, dye photodegradation, NO_x and VOC abatement, and antimicrobial activity—are critically discussed together with the limitations of standardized laboratory tests. Finally, we analyze the weathering-induced deactivation pathways (photocatalyst leaching, surface contamination by soluble salts, and UV aging of organic matrices) and the emerging strategies for durable coatings, including inorganic binders, light-driven hydration, and defect- and heterojunction-engineered photocatalysts. The review concludes with an outlook on the open challenges that must be addressed to translate these coatings from laboratory demonstrations to long-lived, large-scale building applications. Full article

Background: Perfluorooctane sulfonate (PFOS) is a globally recognised persistent, bioaccumulative and toxic pollutant. Under China GB 5749-2022 and the US EPA 2024 drinking water MCL, permissible levels have fallen to 40 ng L⁻¹ and 4 ng L⁻¹, respectively, placing unprecedented demands on remediation technologies. Methods: An iron(III)–carboxylate metal–organic framework prepared from low-cost precursors (denoted MOF-LC, [Fe₃O(BDC)₃Cl]·x(solvent)) was synthesised via a one-pot solvothermal route from FeCl₃·6H₂O and terephthalic acid (H₂BDC). The material was characterised by PXRD, N₂ adsorption, FTIR, TGA, XPS, elemental analysis and ICP-OES. Adsorption performance was evaluated under varying initial concentrations, contact times, pH values, coexisting inorganic anions (Cl⁻, NO₃⁻, SO₄²⁻, HCO₃⁻, PO₄³⁻) and humic acid backgrounds, and by a panel of six water matrices. Results: MOF-LC exhibited a BET surface area of 1528 m² g⁻¹ and a dominant pore centred at 1.9 nm, which is geometrically compatible with the 1.36 nm molecular length of PFOS. Adsorption reached ≈95% of equilibrium capacity within 30 min and was best described by the pseudo-second-order model (R² = 0.998). Measured uptake reached 800.6 mg g⁻¹ at 298 K, corresponding to a Langmuir maximum capacity of 802 mg g⁻¹ (note that all adsorption experiments were conducted at mg L⁻¹ concentrations, several orders of magnitude above the regulatory limits cited above). Removal exceeded 88% across all six water matrices. PFOS removal efficiency fell from 99.2% to 85.8% over seven adsorption–regeneration cycles using a 1% NH₄Cl/methanol eluent, with 90.6% of the initial BET surface area retained and Fe leaching below 45 µg L⁻¹. Conclusions: Electrostatic, hydrophobic and pore confinement contributions are proposed as cooperative interpretations consistent with the observations. MOF-LC is identified as a technically promising laboratory-scale sorbent for PFOS removal from complex water matrices. Performance at environmentally relevant ng L⁻¹ concentrations and economic viability at scale remain to be established. Full article

Next-generation waste degradation and valorization technologies are increasingly developed as integrated platforms for pollutant removal, resource recovery, and circular manufacturing. This review critically evaluates degradation and valorization routes for liquid, organic solid, and inorganic/electronic waste streams from an engineering perspective. For liquid waste, advanced oxidation processes, photocatalysis, electrochemical oxidation, plasma treatment, and hybrid systems are assessed with emphasis on radical utilization, photon and electron efficiency, catalyst stability, byproduct formation, and reactor hydrodynamics. For organic solid waste, biological, thermochemical, catalytic, enzymatic, and mechanical pathways are compared for agricultural residues, textile waste, and industrial polymers, including fermentation, pyrolysis, hydrogenolysis, solvolysis, enzymatic depolymerization, and mechanical recycling. Their practical viability depends strongly on feed purity, product selectivity, monomer or fuel recovery, and the energy and separation requirements of downstream processing. For inorganic and electronic waste, hydrometallurgical, pyrometallurgical, biohydrometallurgical, and physical separation routes are examined for the recovery of critical metals, mineral phases, and non-metallic fractions. Industrially mature integrated flowsheets generally offer greater feed tolerance, whereas emerging selective routes provide improved recovery potential but remain constrained by reagent consumption, reaction rate, and scale. Across all waste classes, the review identifies reactor design, process intensification, reaction–separation integration, techno-economic analysis, and life-cycle assessment as essential tools for translating laboratory performance into scalable, economically competitive, and environmentally sustainable processes. Full article

Mining and metallurgical wastes contain reactive Fe-, Al-, Ca-, Mg-, and Mn-bearing phases. These phases can be used for water treatment. Their performance depends on mineral accessibility, processing history, and water chemistry rather than waste identity alone. This review compares tailings, slags, red mud, and leaching residues for inorganic and organic contaminant removal, focusing on mechanisms, modification intensity, and validation. Cations are removed by ion exchange, surface complexation, and precipitation, whereas anion removal relies on Fe/Al sites, Ca-mediated mineral formation, and redox reactions. Organic treatment proceeds through adsorption or catalytic transformation and generally requires activation or additional functional phases. Red mud and blast-furnace slag showed the broadest applicability across both pollutant classes, although no unchanged formulation was validated for both. Under favorable conditions, waste-derived sorbents can achieve pollutant-removal efficiencies approaching 100% in synthetic solutions. However, their performance generally decreases in real wastewater and under continuous or cyclic operating conditions, with reported efficiency losses reaching approximately 25 percentage points. Deployment and machine-learning-assisted selection require application-matched processing, real-water and static/dynamic validation, and standardized reporting of separation, regeneration, cyclic stability, mass loss, secondary leaching, and spent-material fate. Full article

Efficient removal of organic dye pollutants remains challenging owing to the limited adsorption capacity and poor reusability of most conventional adsorbents. Herein, rhombic-dodecahedral zeolitic imidazolate framework-67 (ZIF-67) was successfully fabricated via a facile aqueous strategy. The obtained ZIF-67 exhibited a high BET specific surface area of 1842.31 m² g⁻¹, with a maximum Langmuir adsorption capacity of 156.74 mg g⁻¹ toward methyl orange (MO). The adsorption kinetics successfully followed the pseudo-second-order model, and the material maintained 88.9% dye removal efficiency after six ethanol-regeneration cycles. Common inorganic anions (HCO₃⁻ and SO₄²⁻) presented a distinct inhibitory effect on MO adsorption. Static electrostatic potential calculations and hydrated molecular dynamics simulations were further adopted to reveal the interfacial adsorption behavior on typical ZIF-67 (100) and (110) facets. Based on equilibrated trajectories of 40–50 ps, both facet systems exhibited stable temperature and potential-energy fluctuations. The dominant Co–O(MO) radial distribution distances for (100) and (110) facets were determined to be 5.825 Å and 5.775 Å, respectively, both far beyond conventional short-range Co–O coordination lengths. The stronger radial ordering of the (110) facet suggests facet-sensitive interfacial organization, rather than direct Co–O chemical bonding during MO adsorption. Full article

The disposal of stone mine tailings (SMTs) near agricultural lands has become a major environmental concern because of their elevated concentrations of environmentally hazardous metals (EHMs). The minimization of the potential detrimental effects of soil pollution on crop cultivation and food safety are the major concerns in modern agricultural practice. Vermitechnology has emerged as a sustainable bioconversion approach for biotically stabilizing mine tailings into a nature-friendly organic amendment. However, the agronomic potential and environmental safety of vermiprocessed stone mine tailings remain poorly understood. To fill this research gap, this study assessed the effectiveness of mine-tailing-derived vermicompost as an organic amendment for Solanum lycopersicum L. (tomato) cultivation. Vermicompost was prepared from both inorganic mine tailings and organic cow dung (1:1 and 2:1 ratios, w/w) together using earthworm Eisenia fetida species. The results demonstrated that the treatment amended with 1:1 vermicomposted tailings supplemented with the recommended dose of chemical fertilizer (T3) outperformed all other treatments by enhancing soil microbial activity, the concentration of bioavailable NPK, improved fruit yield, different biochemical parameters, and reduced post-harvest bioavailable Cr, Ni, Cu, Pb, and Cd concentration. Severity Adjustment Margin of Exposure (SAMOE) analysis indicated estimated dietary risk (Class 5) for Cr (VI) and Cd in tomatoes grown on untreated mine tailings, whereas vermicompost-amended treatments reduced the risk to low or negligible levels. Overall, the findings suggest that vermicomposted stone mine tailings emerged as a potential complementary soil amendment and an eco-friendly strategy which improve crop growth while reducing metal availability and its associated health risks. Full article

Over the past decade, stringent emission control policies have been implemented in the North China Plain, fundamentally altering regional air pollution profiles. This study investigates the long-term temporal evolution (2015–2025) and chemical reconstruction of air pollutants in Jinan, China. Benefiting from rigorous emission controls, annual median concentrations of PM_2.5, SO₂, and CO decreased significantly by 64%, 81%, and 54%, respectively. Conversely, NO₂ exhibited a slower decline (47%), and the maximum 8-h daily average (MDA8) ozone (O₃) increased by 23%. Generalized additive model (GAM) analysis identified solar radiation, temperature, relative humidity, and NO₂ as the primary factors strongly associated with O₃ variations. The amplified atmospheric oxidation capacity driven by O₃ has triggered a profound chemical reconstruction of secondary inorganic aerosols (i.e., SO₄²⁻, NO₃⁻, and NH₄⁺), with a significant increase in sulfur and nitrogen oxidation ratios (SOR and NOR), which may continue to intensify the combined pollution trend of ozone and PM_2.5. These findings emphasize that coordinated reductions in nitrogen oxides and volatile organic compounds must be achieved in future air quality management while also taking into account the promoting effect of climate warming on ozone generation. Full article

Lead (Pb²⁺) pollution poses a severe threat to the ecological environment and human health due to its high toxicity, bioaccumulation, and refractory nature. Traditional treatment technologies for lead-contaminated wastewater, such as chemical precipitation, ion exchange, and membrane separation, often face limitations, including secondary pollution, high costs, and high energy consumption. In contrast, adsorption has emerged as a promising alternative technology with advantages such as a simple process, high efficiency at low concentrations, and renewability. Biomass-based hydrogels and their composite systems, as novel green adsorbent materials, combine the abundant functional groups of natural biomass with the structural stability, high porosity, and recoverability of hydrogels through a three-dimensional cross-linked network, offering unique advantages for lead ion adsorption. Depending on their composition, these systems range from fully biodegradable pure biopolymer networks to partly biodegradable or biomass-containing composites incorporating inorganic, carbon-based, or metal–organic framework (MOF) materials. This paper systematically reviews the latest research progress on cellulose, lignin, sodium alginate, chitosan, starch-based hydrogels, and their composite systems for lead (Pb²⁺) adsorption. First, the structural characteristics, cross-linking mechanisms, and functional modification strategies of various biomass hydrogels are introduced. Then, the adsorption mechanisms of Pb²⁺, including multiple modes of action such as coordination complexation, ion exchange, electrostatic interaction, and physical adsorption, are systematically analyzed. The adsorption performance of different material systems is compared in detail. The regeneration and recycling performance, as well as the potential practical applications, of the materials are evaluated. On this basis, the main challenges in current research are summarised: balancing adsorption capacity and mechanical strength, achieving selective adsorption in actual wastewater, improving regeneration efficiency, and optimizing costs. In addition, future development directions for biomass hydrogel adsorbent materials are discussed, including the design of multi-functional composite materials, the development of intelligent, responsive hydrogels, engineering-scale-up, and life-cycle assessment. This review aims to provide a theoretical framework and technical roadmap for the rational design of high-performance, sustainable hydrogel adsorbents and to promote their engineering application for the treatment of lead-contaminated wastewater. Full article

Inorganic tin (Sn) is an emerging pollutant whose phytotoxicity and plant detoxification mechanisms remain poorly understood. Here, we demonstrate that inorganic Sn severely inhibits root growth and triggers ROS accumulation in Lemna minor and Arabidopsis. We identified the transcription factor STOP1 as a critical regulator of Sn tolerance. Mechanistically, STOP1 confers Sn tolerance primarily by activating the citrate transporter MATE, contrasting sharply with Al tolerance which relies heavily on the malate transporter ALMT1. Inorganic Sn stress strongly induced root citrate exudation, and the mate mutant displayed severe Sn hypersensitivity. Exogenous citrate application effectively rescued root growth by impeding Sn uptake and attenuating ROS overaccumulation. Our study reveals that the STOP1-MATE-citrate axis constitutes a pivotal detoxification mechanism against inorganic Sn, providing novel insights into how plants adapt to heavy metal stress through distinct organic acid secretion pathways. Full article

Automotive paint sludge (APS) is a hazardous industrial waste generated during automotive coating operations and is characterized by high moisture content, variable organic and inorganic composition, volatile organic compounds, pigments and heavy metals. Conventional disposal methods, including landfilling and direct incineration, present increasing environmental and regulatory challenges, thereby motivating interest in thermochemical conversion technologies for APS valorization and energy recovery. This review evaluates the current state of research on APS thermochemical conversion through incineration, pyrolysis and gasification pathways. The review compares the major operational characteristics of thermochemical pathways, including reactor conditions, temperature ranges, product yields, energy recovery potential, pollutant formation and downstream cleanup requirements. Also, techno-economic considerations such as drying energy demand and scale-up limitations are discussed. According to the current literature, incineration is the most industrially mature route for APS destruction, whereas pyrolysis offers more flexibility for fuel and material recovery. Gasification shows potential for syngas and hydrogen production but remains insufficiently studied for APS applications. Despite growing interest in APS valorization, a lot of research gaps remain regarding standardized feedstock classification, pilot-scale validation, process integration, environmental risk assessment and techno-economic optimization. Conclusively, future approaches towards managing APS would need to incorporate process optimization for specific APS types, incorporation of co-processing techniques, as well as an overall assessment for both environmental and economic feasibility. Full article

Long-term open-air storage of coal gangue (CG) can generate leachates containing oxidizable components contributing to chemical oxygen demand (COD), together with sulfate (SO₄²⁻) and fluoride (F⁻), yet their source-term behavior remains poorly understood. In this study, batch and column leaching tests were conducted on multi-source CG samples and combined with ToF-SIMS (surface compositional mapping), solid-phase TOC gradient leaching, and PHREEQC-XGBoost-SHAP modeling (coupled geochemical–machine learning analysis). Batch-leachate COD levels ranged from 4.6 to 68.0 mg/L, while SO₄²⁻ and F⁻ concentrations reached maxima of approximately 317 and 1.29 mg/L, respectively. During column leaching, COD levels and SO₄²⁻ concentrations were highest at low liquid-to-solid ratios (L/S) and subsequently decreased, with maximum initial values of 186.6 and 3074 mg/L, respectively, whereas F⁻ exhibited delayed and persistent release at approximately 0.3–2.3 mg/L. Solid-phase TOC did not directly predict the COD response, and ToF-SIMS revealed aliphatic organic fragments associated with aluminosilicate surfaces that weakened or were redistributed after leaching. The COD–DOC discrepancy further indicated that dissolved organic matter alone could not fully explain the COD response, although the possible contribution of inorganic reducing species requires direct verification. Within the modeled framework, the sulfate source-term coefficient accounted for 69.4–76.9% of the modeled influence at L/S = 0.5–2.0 L/kg, while the influence of the HFO surface complexation increased during later leaching. In contrast, the F⁻ source-term coefficient remained dominant over L/S = 0.5–10.0 L/kg, accounting for 97.0–97.9% of the modeled influence. These findings support parameter- and stage-specific monitoring and pollution control at CG disposal sites. Full article

Urban sewer sediments represent an underexplored reservoir of recoverable organic resources, yet conventional disposal practices, landfilling and incineration perpetuate greenhouse gas emissions and irreversible carbon loss. This study establishes a pH-regulated pretreatment strategy (pH 4, 6, 10, and 12) for selective release of organic matter from sewer sediments under simulated hydraulic conditions (solid-to-liquid ratio of 10 g/L, 1154 rpm). Pronounced non-linear release response across the pH revealed a crucial window at pH 10, where COD release attained 1488.68 mg/L (42.6% enhancement over controls) with a 93.70% organic dissolution rate, while total phosphorus release was simultaneously suppressed by 22.4%. The resulting liquid-phase carbon-to-nitrogen and carbon-to-phosphorus ratios of 62.9 and 320.8, respectively, markedly surpassed control values of 46.0 and 174.5, highlighting the potential for high-quality external carbon source recovery. The mechanistic underpinning integrates mineral surface deprotonation, EPS disintegration, and calcium–phosphorus precipitation. Extrapolated to China’s national sewer network, this strategy could potentially mitigate methane emissions by approximately 1.73 × 10⁷ t/yr and save wastewater treatment plants USD 794.83 million/yr in carbon procurement, while inorganic residues retain potential for construction material reuse. This study offers a feasible pathway toward integrated pollution control and high-value waste valorization, aligning with circular economy objectives in urban water systems. Full article

Microplastics (MP) are emerging pollutants found in the Veracruz Reef System National Park (PNSAV). They are widely distributed in the aquatic environment and are ingested by organisms either accidentally or because they are mistaken for food. In this article, the author analyses the physicochemical characteristics of reef sediments using visual identification, Nile Red (NR), scanning electron microscopy (SEM), and Energy Dispersive Spectroscopy (EDS) of microplastics found in sediments adjacent to reefs; this allowed us to determine their distribution within the PNSAV. A total of 687 microplastics per kilogram of dry sediment were quantified, including fibres (98.5%), films (1.4%), and fragments (0.01%). The predominant colour was transparent (60.2%), followed by blue (16%) and red (12%). Based on their MP distribution, the sites were classified into two groups: north and south. The sampling stations with the highest concentrations of MP are located in the group of reefs south of the PNSAV, with the Anegadilla Reef being the most affected station. SEM/EDS analyses revealed elemental spectra dominated by carbon and oxygen, which is consistent with the expected elemental composition of polymeric materials. Peaks of chlorine were detected in some MP particles, suggesting the possible presence of chlorinated polymers, such as polyvinyl chloride (PVC). In addition, elements such as titanium, silicon, and nickel were identified, which could be associated with inorganic particles adhering to the surface or with additives commonly incorporated during the manufacture of plastics such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polyethylene terephthalate (PET). The presence of elements such as titanium and nickel were detected; these are found in additives used in the manufacturing of polymers. Full article

Photocatalytic decomposition of water to produce hydrogen and the degradation of organic pollutants are among the most ideal strategies for addressing energy shortages and environmental pollution. Moreover, constructing organic–inorganic heterojunctions based on surface interactions is one of the most effective strategies for enhancing photocatalytic activity. In this work, a novel II-type polyimide/zinc sulfide (PI/ZnS) heterojunction photocatalyst was successfully synthesized for the first time through a simple hydrothermal method. The influence of PI in the PI/ZnS composite material was systematically studied. The 1PI/ZnS composite shows the highest rate (587.7 μmol/g/h) of photocatalytic water splitting for hydrogen production, which is approximately 19% higher than the value of ZnS (492.5 μmol/g/h), and it is 34.6 times the PI value (16.95 μmol/g/h). The degradation efficiency of the 3 PI/ZnS composite is nearly 35.5 times that of PI and nearly 1.9 times that of ZnS. The enhancement in the photocatalytic activity of the PI/ZnS photocatalyst is mainly attributed to the dense interface and II-type heterojunction between the PI and ZnS, which effectively improves the spatial separation efficiency of photogenerated carriers. This study demonstrates that the nanostructured II-type heterojunction in the PI/ZnS composite can significantly improve the photocatalytic performance of polyimide photocatalysts. Full article

Landfill leachate represents a long-term source of contamination that may significantly affect groundwater and receiving water bodies through the migration of organic, inorganic, and toxic pollutants. This study evaluated the long-term migration of landfill leachate and its potential environmental impacts using the LandSim Release 2 probabilistic software model applied to two municipal waste landfills in the Republic of Serbia: the regional sanitary landfill “Gigoš” in Jagodina and the sanitary landfill “Meteris” in Vranje. The modelling framework integrated laboratory leachate analyses, hydrogeological conditions, engineered barrier system characteristics, and receptor-oriented contaminant transport assessment. Model validation was performed through comparison of simulated and laboratory-measured concentrations. Two scenarios were analyzed for each site: an engineered sanitary landfill scenario with a functional containment system and a conservative barrier-failure scenario representing complete loss of engineered barrier functionality. Ten representative leachate parameters were included, covering nitrogen compounds, inorganic ions, toxic substances, and heavy metals/metalloids. The results showed that engineered protection systems significantly delay contaminant migration and reduce receptor concentrations, while barrier-failure conditions lead to earlier pollutant breakthrough and higher environmental risk. The simulations demonstrated that under the engineered sanitary landfill scenario, receptor concentrations of all analyzed contaminants remained below the corresponding maximum allowable concentrations, with contaminant migration occurring only after several centuries. In contrast, the conservative barrier-failure scenario resulted in substantially earlier contaminant breakthrough, with nitrogen compounds and phenols representing the greatest environmental concern due to their rapid migration and exceedance of regulatory thresholds, while the “Meteris” landfill generally exhibited higher receptor concentrations than the “Gigoš” landfill. These findings highlight the importance of predictive modelling and long-term monitoring for sustainable landfill management and groundwater protection. Full article