Search Results (243)

Waste electrical and electronic equipment (WEEE) is one of the fastest-growing waste streams globally. Disposable e-cigarettes are among the products that have gained popularity in recent years. Their complex construction and embedded lithium-ion batteries (LIBs) present environmental, safety, and resource recovery challenges. Despite growing research interest, integrated analyses linking material composition with user disposal behavior remain limited. This study is the first to incorporate device-level mass balance, material contamination assessment, battery residual charge measurements, and user behavior to evaluate the waste management challenges of disposable e-cigarettes. A mass balance of twelve types of devices on the Polish market was performed. Plastics dominated in five devices, while non-ferrous metals prevailed in the others, depending on casing design. Materials contaminated with e-liquid residues accounted for 4.4–10.7% of device mass. Battery voltage measurements revealed that 25.6% of recovered LIBs retained a residual charge (greater than 2.5 V), posing a direct fire hazard during waste handling and treatment. Moreover, it was estimated that 7 to 12 tons of lithium are introduced annually into the Polish market via disposable e-cigarettes, highlighting substantial resource potential. Survey results showed that 46% of users disposed of devices in mixed municipal waste, revealing a knowledge–practice gap largely independent of gender or education. Integrating technical and social findings demonstrates that improper handling is a systemic issue. The findings support the relevance of eco-design requirements, such as modular casings for battery removal, alongside the enforcement of Extended Producer Responsibility (EPR) schemes. Current product fees (0.01–0.03 EUR/unit) remain insufficient to establish an effective collection infrastructure, highlighting a key systemic barrier. Full article

The circular economy approach aims to reduce raw material use and limit landfill disposal of industrial by-products. In the metal casting industry, waste foundry sand (WFS) disposal is a persistent financial and environmental challenge due to hazardous metal contamination. This study assessed three South African ferrous foundries’ sand streams—virgin, fettling/shot blast, and moulding/shakeout—using the toxicity characteristic leach procedure (TCLP) under the South African Waste Management Act. Results showed that while virgin sand was inert, fettling/shot blast and shakeout sands contained elevated Cr (0.024–1.02 mg/L), Mn (62–97 mg/L), and Ni (0.14–3.26 mg/L), exceeding inert waste thresholds (Cr: 0.05 mg/L; Mn: 0.5 mg/L; Ni: 0.07 mg/L). The shakeout sand, which accounts for 50–70% of total foundry waste, was the most critical stream. Particle size analysis revealed that the majority of sand (70%) falls between 600 and 75 µm, with hazardous metals concentrated in fine fractions (<150 µm). These fines contained up to 94–97% magnetic metallic debris, primarily Cr, Mn, and Ni, and exhibited TCLP leachability above inert classification limits. By contrast, coarser fractions (>150 µm) had low leachability and characteristics comparable to virgin sand. A simple size segregation treatment reduced hazardous metal content by up to 93–97%, rendering 75–85% of shakeout sand inert, while only 10–15% (fine portion) required hazardous waste disposal. These findings highlight that targeted removal of fines can substantially reduce disposal costs and environmental risk, supporting greener and more sustainable foundry operations. Full article

The production and use of Li-ion batteries (LIBs) is steadily increasing each year, leading to a growing number of battery-powered products. Consequently, the number of chemical hazards associated with the operation and other stages of the life cycle of this type of cell is increasing as well. Therefore, this study examined the impact of selected extinguishing agents for extinguishing Li-ion battery fires—namely, a dedicated extinguishing granulate, a natural sorbent (exfoliated vermiculite), and quartz sand—on the level of heat and released substances. The study determined the emission of heavy metals and polycyclic aromatic hydrocarbons (PAH) into the air during a cell fire, the concentration of the inhalable aerosol fraction, and the concentration of hazardous substances in the extinguishing agent residue. The analysis concluded that quartz sand provides the most effective heat removal and insulation of the battery from the external environment, which also reduces the amount of pollutants released into the environment. Full article

The treatment of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/Fs) in incineration fly ash presents a significant challenge in solid hazardous waste management. This study systematically analyzed the influence mechanisms of multiple factors on the removal efficiency of PCDD/Fs during fly ash pyrolysis. It integrated 4068 datasets conducted between 2010 and 2025 through meta-analysis. Results show that Al₂O₃, CaO, SiO₂, and Cl in fly ash components enhance the removal efficiency by 14.0%, while Fe₂O₃ (Content greater than 5.7%) exhibits inhibitory effects. Cd and Cr demonstrate a bimodal response pattern: low/high concentrations promote removal, while medium concentrations inhibit it. Process optimization identified the optimal parameter combination as pyrolysis temperatures of 500–900 °C, residence time of 50–90 min, and a gas flow rate greater than or equal to 400 mL/min. A significant negative correlation was observed between the initial dioxin concentration and removal efficiency. This study established a structural equation modeling (SEM) model to describe how metallic and nonmetallic components, fly ash components, and pyrolysis conditions determine removal efficiency. Fly ash composition was confirmed as the most influential factor (total effect = 0.3194), with fixed carbon and ash content being the most reliable indicators. Among pyrolysis conditions, gas conditions (flow rate, gas type) also significantly affected removal efficiency (total effect = 0.2357). Conversely, nonmetallic components and excessively prolonged pyrolysis time (beyond the window) consistently reduced removal efficiency. These findings provide theoretical support for upgrading fly ash pyrolysis processes toward low-carbon and resource-efficient operations. Full article

Pollution of water resources with hazardous substances of anthropogenic origin (e.g., synthetic dyes, heavy metal ions) is currently one of the most important environmental issues, and the development of not only effective and economical but also eco-friendly methods of removing these substances from aqueous solutions is one of the greatest challenges. Among the various separation methods, techniques based on the utilization of different types of polymer membranes have gained increasing interest due to their usually high efficiency, the materials’ stability and reusability, and the possibility of using “green” components for their formation. Recent research efforts have been concentrated, inter alia, on the application of natural polysaccharide polymers (e.g., cellulose, alginates, starch, cyclodextrins) and their derivatives to produce well-performing membranes. Appropriately composed polysaccharide-based membranes under optimal process conditions enable effective separation of dyes, salts, and metal ions (e.g., often with a rejection rates of >95% for dyes and metal ions and <7% for salts). This review concerns the latest developments in the formation and utilization of novel polysaccharide-based membranes for the separation of synthetic dyes and metal ions from aqueous solutions and suspensions, with emphasis on their most important advantages, limitations, and potential impact on the environment and sustainability. Full article

Mercury (Hg²⁺) contamination in water systems poses a severe environmental and health hazard due to its high toxicity and bioaccumulation potential. In this study, a novel adsorbent was developed by sequentially modifying kaolin via acid–base treatment, titanium dioxide (TiO₂) incorporation, and 3-aminopropyltriethoxysilane (APTES) grafting. Batch adsorption experiments revealed that the fully modified kaolin (TiO₂-loaded and APTES grafted) exhibited the highest adsorption capacity (25.6 mg/g) compared to the acid–base-treated (5.8 mg/g) and TiO₂-loaded (17.7 mg/g) kaolin. Under optimal conditions (75 mg adsorbent dosage; 70 mg/L Hg²⁺; pH 5), the fully modified kaolin maintained its performance even in the presence of varying ionic strengths, natural organic matter, and competing metal ions. Adsorption kinetics followed a pseudo-second-order model, and the equilibrium data were well fitted by the Langmuir isotherm. Antibacterial activity assay revealed that the TiO₂-loaded kaolin effectively inhibited S. aureus (minimum inhibitory concentration = 2.5 mg/mL) and showed moderate activity against E. coli (BL21) (minimum inhibitory concentration = 5 mg/mL). However, antibacterial activity decreased after amine functionalization, indicating a compromise between enhancing adsorption capacity and preserving antibacterial functionality. This study presents a promising cost-efficient approach for the simultaneous removal of Hg²⁺ ions from water matrices and inhibiting bacterial growth, aligning with SDG 6 (Clean Water and Sanitation). Full article

Municipal solid waste incineration (MSWI) fly ash, classified as hazardous waste (HW18) due to the presence of heavy metals and dioxins, necessitates both harmless treatment and resource utilization. In this study, a Na-P1 zeolite adsorbent was synthesised from MSW incineration fly ash using its intrinsic Si and Al sources, supplemented by silica sol and sodium aluminate solution. The synthesised zeolite was employed for the adsorption removal of tetracycline hydrochloride (TCH) from wastewater. Under the optimised conditions (initial TCH concentration of 10 mg·L⁻¹, adsorbent dosage of 0.4 g·L⁻¹, pH 5.0, temperature 45 °C, and contact time 60 min), a maximum adsorption capacity of 14.8 mg·g⁻¹ and a removal efficiency of 59.1% were achieved. Kinetic analysis revealed that the adsorption process followed the pseudo-first-order model (R² = 0.975). The Langmuir isotherm provided a better fit than the Freundlich model (R² = 0.988), indicating monolayer adsorption on homogeneous sites. Thermodynamic parameters (ΔG < 0, ΔH > 0) confirmed that the adsorption was spontaneous and endothermic, with higher temperatures favoring enhanced TCH adsorption. This work demonstrates the feasibility of converting hazardous MSW incineration fly ash into a value-added Na-P1 zeolite adsorbent with excellent performance for antibiotic wastewater treatment, thereby offering a sustainable strategy for fly ash resource recovery and environmental remediation. Full article

The intensification of industrialization and increasing energy consumption have led to elevated emissions of hazardous gases such as NO, NO₂, and SO₂, making their efficient capture and removal crucial for environmental remediation. In this work, first-principles calculations were employed to systematically investigate the adsorption behavior of these gases on single-atom-decorated (Sc, Ti, and V) 1T-ZrS₂ monolayers. The results indicate that the transition metal atoms preferentially occupy the hexagonal hollow sites of ZrS₂, forming an approximately octahedral coordination field and exhibiting characteristic d-orbital splitting. During gas adsorption, the decorated systems exhibit pronounced metal-to-adsorbate charge donation and strong d-p hybridization, indicative of strong chemisorption. Notably, Ti-ZrS₂ exhibits the strongest adsorption toward NO₂, inducing partial molecular dissociation and suggesting catalytic activity, whereas Sc- and V-decorated systems predominantly maintain molecular adsorption. Recovery time calculations indicate that the adsorption processes are comparatively stable, making these systems suitable for gas capture and pollution abatement. Overall, single-atom decoration provides an effective strategy to modulate the electronic structure and gas interactions of ZrS₂, highlighting its potential as an efficient gas scavenger for NO, NO₂, and SO₂. Full article

With the expansion of industrial production capacity, a substantial volume of hazardous wastewater containing Pb (II) and Ni (II) requires treatment. Kaolin, a low-cost adsorbent with strong adsorption properties, was modified through thermal activation at 750 °C, 850 °C, and 950 °C to enhance its adsorption capacity. Following the optimization of pH, reaction time, temperature, heavy metal concentrations, and adsorbent amount, the 850-K was found to have the best removal efficiency, achieving removal rates > 90% for both PbCl₂ and NiCl₂, and the removal efficiency of PbCl₂ was higher compared to NiCl₂. The pseudo-second-order kinetics and Langmuir model could reasonably match the adsorption processes of PbCl₂/NiCl₂. The experimental findings were corroborated through simulations of adsorption distance, variations in bond length/bond angle, adsorption energy, frontier molecular orbital, charge density, and differential charge density. The differences in reactions between adsorbents and PbCl₂/NiCl₂ were primarily due to the electron transfer direction and bonding mechanisms. The O atoms were the main reactive atoms of the adsorbents, capable of forming covalent bonds with both PbCl₂ and NiCl₂, and the Cl atoms could form either ionic or covalent bonds with the adsorbent. Pb could form covalent bonds with the adsorbent, while Ni might be adsorbed through electrostatic interactions. Full article

Emerging organic contaminants (EOCs), including polychlorinated bisphenyls (PCBs), pharmaceuticals, personal care products, pesticides, polycyclic aromatic hydrocarbons (PAH), and dyes, are among the most hazardous pollutants found in water bodies and sediments. These substances pose serious threats to the environment and human health due to their high toxicity, long-range mobility, and bioaccumulation potential. Although various methods for degradation of organic pollutants exist, photocatalysis using ultraviolet (UV) and visible light (VIS) has emerged as a promising approach. However, its practical applications remain limited due to challenges such as the use of powdered photocatalysts, which complicates their removal and recycling in industrial settings, and the restricted solar availability of UV light (~4% of the solar spectrum). This review investigates the effectiveness of hybrid electrospun conductive polymer nanofibers on metal oxide photocatalysts such as TiO₂ and ZnO (including doped and co-doped forms) and fabricated via mono- or coaxial electrospinning, in the degradation of EOCs in water under visible light. Furthermore, strategies to enhance the fabrication of these hybrid electrospun conductive nanofibers as visible-light-responsive photocatalysts, such as the inclusion of dopants and/or plasmonic materials, are discussed. Finally, the current challenges and future research directions related to electrospun nanofibers combined with photocatalysts for the degradation of EOCs in water treatment applications are outlined. Full article

Arsenic-containing wastewater and soil systems are a serious hazard to public health and the environment, particularly in areas where agriculture and drinking water depend on groundwater. Therefore, the removal of arsenic contamination from soil, water, and the environment is of great importance for human welfare. Most of the conventional methods are inefficient and have very high operational costs, especially for metals at low concentrations or in large solution volumes. This review delivers a comprehensive approach to arsenic remediation, including microbiological processes, phytoremediation, biochar technologies, bio-based adsorbents, and nanomaterial-assisted techniques. All of these methods are thoroughly examined in terms of removal competence, their mechanisms, environmental impact, cost-effectiveness, and scalability. Phytoremediation and microbial remediation techniques are self-regenerating and eco-friendly, whereas fruit-waste-derived materials and biochar provide abundant adsorbents, and are therefore low-cost. On the other hand, nanotechnology-based approaches show remarkable effectiveness but raise concerns regarding economic feasibility and environmental safety. Additionally, this review represents a comparative analysis and discusses synergistic and hybrid systems that combine multiple technologies for enhancing the remediation performance. Future research directions are emphasized along with challenges such as material stability, regeneration, and policy integration. This review aims to guide decision-makers, research scholars, and industry stakeholders toward affordable, sustainable, and high-performance arsenic remediation techniques for practical use. Full article

The growing demand for ultra-low sulfur fuels has intensified interest in recovering strategic metals from the large volumes of hazardous hydrodesulfurization catalysts that are discarded yearly. This work evaluates a task-specific ionic liquid, tri-n-octylammonium bis(2-,4-,4-trimethylpentyl)-phosphinate [TOA][Cy272], synthesized by the acid–base neutralization of tri-n-octylamine and Cyanex 272. FT-IR spectroscopy confirmed complete proton transfer and the formation of a stable ion pair. Liquid–liquid extraction tests were conducted with synthetic Co–Ni–Mo solutions (0.1–2.5 g/L each), a varying ionic liquid concentration (10–50 vol%), pH (1.5–12.5), and organic/aqueous ratio (1:1). At 35 vol% of ionic liquid and pH 2, the extraction efficiency for Mo reached 94%, with separation factors βMo/Ni = 12 and βMo/Co = 7.5; Co and Ni uptake remained ≤15%. Selectivity decreased at higher metal loadings because of ionic liquid saturation, and an excessive ionic liquid amount (>35%) offered no benefit, owing to viscosity-limited mass transfer. Stripping studies showed that 1 M NH₄OH stripped about 95% Mo, while leaving Co and Ni in the organic phase; conversely, 2 M HCl removed 92–98% of Co and Ni, but <5% Mo. Overall Mo recovery of about 95% was obtained by a two-step extraction/stripping scheme. The results demonstrate that [TOA][Cy272] combines the cation exchange capability of quaternary ammonium ILs with the strong chelating affinity of organophosphinic acids, delivering rapid, selective, and regenerable separation of Mo from mixed-metal leachates and wastewater streams. Full article

This review examines the research progress on non-noble-metal-based catalysts for formaldehyde (HCHO) oxidation at room temperature. It begins with an introduction to the hazards of HCHO as an indoor pollutant and the urgency of its removal, comparing several HCHO removal technologies and highlighting the advantages of room-temperature catalytic oxidation. It delves into the classification, preparation methods, and regulation strategies for non-precious metal catalysts, with a focus on manganese-based, cobalt-based, and other transition metal-based catalysts. The effects of catalyst preparation methods, morphological structure, and specific surface area on catalytic performance are discussed, and the catalytic oxidation mechanisms of HCHO, including the Eley–Rideal, Langmuir–Hinshelwood, and Mars–van Krevelen mechanisms, are analyzed. Finally, the challenges faced by non-precious metal catalysts are summarized, such as issues related to the powder form of catalysts in practical applications, lower catalytic activity at room temperature, and insufficient research in the presence of multiple VOC molecules. Suggestions for future research directions are also provided. Full article

Micropollutants (MPs), which include both natural and manmade substances, are becoming more prevalent in aquatic habitats as a result of the insufficient removal of these compounds in wastewater treatment plants (WWTPs). Advanced remediation techniques are required due to their persistence and potential ecotoxicological hazards. Although adsorption and photo(electro)catalysis exhibit potential in laboratory-scale investigations, the effects of their use in actual WWTP systems are still poorly understood. However, before large-scale application can be implemented, a number of issues need to be resolved, including material limitations, reactor design and optimization, and actual wastewater complexities. This study critically evaluates the application of adsorption and photo(electro)catalysis to actual wastewater, as well as recent advancements in adsorption and photo(electro)catalytic systems for the removal of micropollutants. We also explore the particular difficulties and strategies involved in the large-scale use of adsorption and photo(electro)catalysis in the treatment of wastewater. Emerging trends such as nanocomposites, metal–organic frameworks (MOFs), heterojunctions, and single-atom catalysts (SACs) are highlighted by the bibliometric analysis. We also evaluate MPs’ ecological effects in aquatic environments and the incorporation of artificial intelligence (AI) for process optimization. A strategy for transferring nanotechnologies from laboratory-scale research to wastewater treatment implementation is presented in this paper. In this strategy, implementation is proposed based on actual wastewater conditions, focusing on the development of adsorbents and catalysts, reactor design and optimization, synergy between adsorption and catalysis, life cycle analysis, and cost–benefit studies. Full article

Excess phosphorus (P) and nitrogen (N) in wastewater contribute to eutrophication, driving the need for low–cost and sustainable recovery technologies. This study presents a novel adsorbent synthesized from spent coffee grounds biochar (CB) chemically modified with Mn²⁺/Zn²⁺/Fe³⁺ (oxy)hydroxide nanoparticles (CB–M) for simultaneous removal of phosphate and ammonium. Batch adsorption experiments using both synthetic solution and municipal wastewater were conducted to evaluate the material’s adsorption performance and practical applicability. Kinetic, isotherm, thermodynamic, and sequential extraction analyses revealed that CB–M achieved maximum phosphate adsorption capacities ranging from 42.6 to 72.0 mg PO₄³⁻·g⁻¹ across temperatures of 20–33 °C, reducing effluent phosphate concentrations to below 0.01 mg·L⁻¹. Ammonium removal was moderate, with capacities ranging between 2.8 and 2.95 mg NH₄⁺·g⁻¹. Thermodynamic analysis indicated that phosphate adsorption was spontaneous and endothermic, dominated by inner–sphere complexation, while ammonium uptake occurred primarily through weaker, reversible ion exchange mechanisms. Sequential extraction showed over 70% of adsorbed phosphate was associated with Fe-Mn-Zn phases, indicating the potential for use as a slow–release fertilizer. The CB–M retained structural integrity and exhibited partial desorption, supporting its reusability for nutrient recovery. Compared to other biochars, CB–M demonstrated superior phosphate selectivity at a neutral–pH, avoided the use of hazardous metals, and transformed coffee waste into a multifunctional material for wastewater treatment and soil amendment. These findings underscore the potential of CB–M as a circular economy solution for nutrient recovery without introducing secondary contamination. Full article