Search Results (878)

In line with circular economy principles, raw spent yerba mate (Ilex paraguariensis) waste (YMs) was transformed into a high-value aminated adsorbent (AYMs) for the removal of anionic dyes, namely Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84). The modification involved a two-step process using epichlorohydrin and aqueous ammonia, and the adsorbents were characterized via FTIR, BET, C/N elemental analysis, and pH_PZC. Batch experiments evaluated pH effects, kinetics (PFO, PSO, and intraparticle diffusion), and equilibrium isotherm analysis (single- and dual-site Langmuir models and Freundlich models). The results confirmed successful functionalization of the biomass with amino groups, shifting the point of zero charge (pH_PZC) from 4.74 (YMs) to 8.73 (AYMs). The optimal adsorption pH was 2.0 for YMs and 3.0 for AYMs. Kinetic data were best described by the pseudo-second-order model, while equilibrium data followed the dual-site Langmuir model, indicating energetic heterogeneity of the AYMs surface. The maximum adsorption capacity of AYMs reached 62.81 mg·g⁻¹ for RB5 and 61.78 mg·g⁻¹ for RY84, representing a fivefold and threefold increase over the YMs, respectively. These findings demonstrate that AYMs is a high-performance, sustainable alternative to commercial activated carbons, providing a scalable waste-to-value solution for industrial effluent treatment. Full article

In this study, Zn-doped Co₃O₄ nanorods and nanosheets with controlled Zn/Co molar ratios were synthesized via a hydrothermal strategy to clarify the respective roles of morphology and elemental doping in ethylbenzene sensing. The gas-sensing performance is strongly influenced by morphology, and the radially oriented nanorod structure significantly enhances sensing response compared with nanosheet structures. Zn doping effectively enhances the gas-sensing performance of Co₃O₄. As a result, the optimized Zn-doped nanorod sensor exhibits high sensitivity to ethylbenzene, a low detection limit, rapid response and recovery, and excellent operational stability. Density functional theory calculations reveal that the predominantly exposed facets of the nanorod structure possess stronger adsorption affinity and pronounced charge transfer toward ethylbenzene, providing theoretical support for the morphology-dominated sensing behavior. At the same time, Zn incorporation further adjusts the band structure and surface reactivity. Overall, this work elucidates a morphology-dominated and doping-assisted enhancement mechanism, offering clear design principles for high-performance Co₃O₄-based ethylbenzene sensors. Full article

Indium oxide was mechanically activated, and its effect on the operation of semiconductor gas-sensitive devices was evaluated. The structural and morphological characteristics of In₂O₃ following mechanical activation were examined. The powder treatment produced a defective particle surface structure, enhanced specific surface area, and improved material diffusion properties. Experimental evidence indicates a substantial enhancement in the reactivity of indium oxide with diverse gases, stemming from alterations in grain structure and the formation of novel adsorption sites. The results obtained demonstrate that mechanoactivation is a promising technological tool for the development of energy-efficient sensors. Full article

This review examines microplastics (MPs) in aquatic environments, their interactions with organic pollutants (OPs), effects on organisms, and implications for human and ecological health. MPs are ubiquitous, persistent contaminants. Their small size and large surface area enhance adsorption of diverse OPs; however, the extent to which MPs influence pollutant transport, fate, and bioavailability remains highly context-dependent and is still under scientific debate. Sorption processes are influenced by polymer type, pollutant properties, environmental factors, and aging processes that increase surface reactivity, further contributing to the variability of MP–OP interactions. Detection of MPs in human tissues raises concerns about long-term health effects, including inflammatory, immune, gastrointestinal, respiratory, and endocrine responses. Despite advances in analytical techniques, challenges remain in identifying and quantifying small particles in complex matrices. This review emphasizes the need for integrated, multi-technique, and environmentally realistic studies to understand MP–OP interactions and support risk assessment. Future research should focus on standardizing methodologies, improving nano-sized particle detection, and elucidating long-term effects, including trophic transfer and potential tissue accumulation. Full article

A nano-CuO/ZnO desulfurizer was successfully prepared via a homogeneous precipitation method, and the effects of Cu doping on its microstructure, oxygen species, desulfurization performance, and reaction mechanism were systematically investigated. The results show that an appropriate Cu doping amount (TZ2, Cu:Zn = 1:18.40) significantly reduces the particle size (to ~10.9 nm) compared with pure ZnO (14.3 nm), leading to an increased number of surface-active sites. XPS and TG analyses reveal that Cu incorporation increases the proportion of lattice oxygen and decreases the concentration of oxygen vacancies, indicating that the modification effect of Cu dominates over the particle size effect in regulating surface oxygen species. Despite the reduced oxygen vacancy concentration, the desulfurization performance is markedly enhanced, with TZ2 exhibiting the longest breakthrough time under oxygen-free conditions at room temperature. This improvement is attributed to the strong interaction between highly dispersed Cu species and the ZnO matrix, which promotes H₂S adsorption and activation. Mechanistic studies demonstrate that, unlike pure nano-ZnO, where oxygen vacancy-mediated reactions dominate, the CuO/ZnO system follows a chemisorption-driven pathway involving the formation of copper sulfides and highly reactive polysulfide intermediates. Furthermore, the presence of oxygen significantly influences the reaction behavior, with an optimal oxygen concentration (~10%) maximizing desulfurization performance by balancing the generation of reactive oxygen species and sulfur intermediates. This work provides new insights into the design of high-performance ZnO-based desulfurizers and highlights the critical role of Cu-induced mechanism transformation. Full article

Hydrogen peroxide (H₂O₂) is an important green oxidant, and developing efficient visible-light-driven routes for its synthesis is highly desirable. Herein, a CN/Zn_V-ZCS composite photocatalyst was constructed by coupling g-C₃N₄ (CN) with Zn-vacancy-containing ZnCdS (Zn_V-ZCS) for photocatalytic H₂O₂ production. The optimized CN/Zn_V-10 delivered 44.58 mmol g⁻¹ H₂O₂ within 60 min under 425 nm LED irradiation, outperforming pristine CN, ZCS, Zn_V-ZCS, and vacancy-free CN/ZCS, with good cycling stability. Trapping and EPR results identify O₂ as the key electron acceptor and ·O₂⁻ as an important intermediate. Structural characterization and XPS results indicate successful Zn-vacancy introduction, intimate heterointerface formation, and interfacial electron redistribution. Combined VB-XPS, photoelectrochemical, and reactive-species analyses suggest that Zn vacancies are favorable for O₂ adsorption/activation, whereas the CN/Zn_V-ZCS heterointerface promotes charge separation and migration. Based on the available evidence, a Z-scheme interfacial charge-transfer pathway is established in the CN/Zn_V-ZCS system. Full article

Bismuth oxychloride (BiOCl) has garnered significant research interest owing to its non-toxicity, affordability, and distinct layered structure. Although BiOCl possesses promising photocatalytic potential, its large band gap and rapid photocarrier recombination restrict its practical use. In this work, a natural tourmaline mineral was effectively integrated with BiOCl to form a composite (TBO). Comprehensive characterization and photocatalytic assessments revealed that the intrinsic electric field of tourmaline notably strengthened both the adsorption capacity and the light-driven catalytic efficiency of BiOCl. Under visible-light irradiation, ofloxacin (OFX, 10 ppm) was eliminated by approximately 98% within 60 min. The apparent reaction rate constant (k) of TBO was 0.0407 min⁻¹, which was approximately 184.8 and 2.26 times those of tourmaline alone and pristine BiOCl, respectively. Furthermore, both the visible-light absorption and the separation efficiency of photogenerated electron–hole pairs were significantly enhanced. After evaluating its behavior under various simulated natural environmental conditions, TBO displayed strong potential for practical application. Reactive species trapping and analysis identified singlet oxygen (¹O₂) and superoxide radicals (·O₂⁻) as the primary active species in photocatalysis. Moreover, the degradation route of ofloxacin and the toxicity of its intermediates were systematically examined. These findings offer meaningful guidance for improving photocatalytic materials by utilizing naturally occurring minerals. Full article

This study investigates lignite, long-flame coal, coking coal, and anthracite to elucidate the rank-dependent evolution of coal macromolecular structure and pore systems. Elemental/proximate analyses, FTIR, XPS, ¹³C NMR, and low-temperature N₂ adsorption–desorption, combined with BET, BJH, and DFT models, were employed to quantify structural parameters, characterize pore-size distributions, and establish representative macromolecular models. The results show that coalification is accompanied by progressive aromatization and polycondensation. Low-rank coal contains abundant hydroxyl, carboxyl, and aliphatic side-chain structures, exhibiting low aromaticity and weak aromatic-ring condensation. With increasing rank, oxygen-containing groups and aliphatic chains are progressively removed, while aromatic carbon content and the bridgehead-to-peripheral carbon ratio increase markedly. High-rank coal is dominated by highly condensed aromatic lamellae, with lower molecular polarity and enhanced structural ordering and graphitization. Meanwhile, N and S occurrence modes evolve from edge-related reactive species to more stable heterocyclic configurations, reflected by increasing graphitic N and thiophenic S contents. Pore structures also change systematically: low-rank coal is characterized by open, multimodal mesopores; intermediate-rank coal shows compaction and mesopore collapse; and high-rank coal becomes micropore-dominated with a relatively closed network. The U-shaped variation in micropore and mesopore volumes with rank indicates coupled macromolecular polycondensation and pore reconstruction, providing a structural basis for spontaneous combustion propensity and coalbed methane occurrence. Full article

Textile wastewater remains one of the most challenging industrial effluents to remediate due to its intense and persistent coloration, high organic load, elevated salinity, and fluctuating pH and the presence of recalcitrant dye structures and auxiliary chemicals. Conventional physicochemical and biological treatments frequently achieve incomplete removal, generate secondary wastes, or fail under high-salt and toxic dye matrices. Advanced oxidation processes (AOPs) provide molecular-level degradation via reactive oxygen species (ROS), yet their deployment is often constrained by narrow operating windows, catalyst instability, chemical/energy demand, and scale-up limitations. In this context, metal–organic frameworks (MOFs) have emerged as tunable porous catalytic platforms that integrate adsorption and oxidation within a single architecture through controllable metal nodes, functional linkers, and engineered pore environments. This critical review reimagines textile effluent treatment through the lens of MOF-based hybrid catalysts, synthesizing progress across Fenton/photo-Fenton catalysis, photocatalytic MOFs, persulfate activation, and MOF-derived/composite systems. Mechanistic pathways are discussed by linking pollutant enrichment, cyclic redox reactions, charge-transfer processes, and ROS-driven degradation toward mineralization, with emphasis on the distinction between rapid decolorization and true organic removal. A critical comparison highlights how hybridization improves charge transport, stability, and catalyst recovery, while persistent gaps remain in hydrolytic robustness, metal leaching control, intermediate toxicity assessment, real-wastewater validation, continuous-flow reactor integration, and techno-economic feasibility. Finally, the review outlines actionable research directions, including water-stable and defect-engineered MOFs, immobilized and structured catalysts, solar-driven operation, standardized performance metrics, and life-cycle-informed design, to accelerate translation toward scalable and sustainable textile wastewater remediation. By bridging material chemistry with reactor-level feasibility and sustainability assessment, this review provides an implementation-oriented perspective for next-generation textile wastewater treatment. Full article

Hydrothermal carbonization (HTC) of agricultural waste is a promising waste management technique. However, the use of different raw materials may produce hydrochars with varying efficiencies, both in yield and application, and environmental impacts, due to differences in composition and required processing conditions. To understand the influence of biomass type and acid-assisted HTC conditions, this study used sugarcane and agave bagasse to produce functionalized hydrochars and evaluated them for the removal of Reactive Orange 84; an azo dye used in the textile industry. Material characterization was performed using FT-IR, TGA, BET, and XRD analyses. In addition, a life cycle assessment was conducted to evaluate environmental impacts associated with hydrochars produced using H₂SO₄ at concentrations of 0.2 and 0.5 M. TGA and XRD results indicate that agave bagasse hydrochars (HBA) retain more crystalline lignocellulosic structures, whereas sugarcane bagasse hydrochars (HBS) exhibit predominantly amorphous structures after HTC. FT-IR analysis confirmed the presence of –SO₃H functional groups; however, HBA samples showed greater availability of these groups with increasing acid concentration. Adsorption experiments and LCA results demonstrated that the most favorable treatment, in terms of emission reduction and dye removal, was agave bagasse functionalized with 0.5 M H₂SO₄, achieving 75.7% mass yield and 94.5% dye removal. Full article

Cerium dioxide (CeO₂) has emerged as a structurally versatile oxide for dye-wastewater purification because its architecture, porosity, and surface accessibility can be tuned over a wide range while maintaining good chemical stability and environmental compatibility. Recent studies show that template-free or low-template routes can generate porous, mesoporous, multilayered, and flower-like CeO₂ architectures with rapid dye uptake and, in some systems, adsorption-assisted photocatalytic removal. However, CeO₂-based dye removal has often been discussed either within broad surveys of environmental applications or from composition-centered viewpoints, whereas the more fundamental question is how synthesis route controls architecture formation and how architecture, in turn, governs adsorption and subsequent removal behavior. This mini-review addresses that question from a morphology-centered perspective. It first examines template-free and low-template routes for constructing structured CeO₂, then discusses how porosity, hierarchical assembly, and surface accessibility regulate adsorption kinetics and equilibrium capacity in dye-containing aqueous systems. It further considers adsorption-assisted photocatalytic removal and argues that dark adsorption should be regarded as the structural first step rather than a secondary contribution. On this basis, the review shows that rare-earth doping in these systems is most usefully understood as a secondary tuning strategy that refines an already favorable host architecture by modifying surface interaction, optical response, or reactive-species generation. Overall, the available evidence indicates that CeO₂-based dye-wastewater purification is most meaningfully interpreted through a route–architecture–function framework in which morphology defines the host, adsorption organizes the local reaction environment, and doping serves mainly as structure-assisted tuning. This perspective shifts the design logic of CeO₂ from empirical performance optimization toward rational structure-directed construction of integrated removal platforms. Full article

Background: The enzymatic saccharification of cellulose is governed by heterogeneous reaction environments that deviate from classical Michaelis–Menten behavior. Methods: Fractal kinetics were applied to describe the hydrolysis of microcrystalline cellulose (Avicel PH-101) and pretreated hemp hurds using Cellic CTec2. Optimal enzyme loading was first established on Avicel, and the influence of mixing regimes was evaluated. Results: Rotational agitation markedly improved hydrolysis efficiency. Organosolv-based pretreatments generated cellulose-enriched substrates that exhibited higher reactivity than Avicel, while redeposited lignin showed minimal inhibitory effects. Enzyme adsorption studies revealed substantial binding to lignocellulosic substrates, suggesting nonspecific interactions and crowding effects that influence kinetic parameters. Conclusions: Fractal coefficients k and h successfully captured differences in substrate accessibility and reactivity, demonstrating the suitability of fractal models for describing cellulose saccharification in complex solid–liquid systems. Organosolv pretreatment allows a high degree of saccharification, whereas redeposited lignin does not interfere with the enzymatic reaction. Full article

We report highly sensitive NO₂ gas sensors based on ZnO thin films prepared via a sol–gel method and deposited onto nanostructured black silicon (b-Si). The b-Si layers, fabricated using maskless reactive ion etching, consist of densely packed silicon nanoneedles with an average height of ~810 nm, a base diameter of ~160 nm, and a characteristic periodicity of ~190 nm. Owing to this highly developed surface morphology, the effective surface area of the b-Si layer is estimated to be approximately one order of magnitude higher than that of planar silicon, thereby enhancing gas adsorption and charge-transfer processes in the ZnO film. ZnO/b-Si/Si sensors exhibit a response of 448% at 25 ppm NO₂ at an optimal operating temperature of 200 °C, which is approximately 1.5 times higher than that of planar ZnO/Si sensors at the same concentration and temperature. Notably, a comparable response (~300%) is achieved at a reduced temperature of 140 °C, indicating the potential for low-power operation. The sensing mechanism is governed primarily by the ZnO layer, while b-Si serves as a morphological scaffold, increasing the effective surface area. These results demonstrate that ZnO-coated b-Si nanostructures represent a promising platform for high-performance NO₂ sensing and offer strong potential for integration with silicon-based microelectronic technologies. Full article

The cocontamination of arsenic (As) and cadmium (Cd) in agricultural soils poses severe risks to ecosystem stability and food safety because of their high toxicity, mobility, and bioaccumulation potential. However, single amendments often exhibit selective immobilization, which limits their effectiveness for As–Cd-cocontaminated soils. In this study, a sepiolite-supported nanoscale zero-valent iron composite (S-nZVI) was synthesized via liquid-phase reduction, and its remediation performance and mechanisms under different moisture conditions were evaluated. The characterization results confirmed that the nZVI nanoparticles were uniformly dispersed and anchored onto the sepiolite matrix, thus mitigating aggregation and oxidative passivation while increasing surface reactivity. Soil incubation experiments demonstrated that S-nZVI reduced the bioavailability of As and Cd and promoted their transformation from labile to stable fractions under both 50% and 120% water holding capacity (WHC). Under flooded conditions (120% WHC), 0.5% S-nZVI reduced the bioavailable Cd and As concentrations by 52.3–58.7% and 67.4%, respectively, after 120 days. Mechanistically, immobilization was governed by a synergistic “adsorption–reduction–coprecipitation” pathway coupled with pH–Eh regulation. Rice pot experiments further validated the effectiveness of S-nZVI, with the grain As and Cd concentrations reduced by 73.3% and 52.3%, respectively, without impairing plant growth. Overall, S-nZVI provides an efficient strategy for simultaneous immobilization of As and Cd in As–Cd-cocontaminated soils and supports the safe use of polluted agricultural lands. Full article

The TiO₂-modified LaMnO₃ catalyst demonstrated outstanding catalytic performance across a broad pH range (4.2 to 10.0) and under various complex water conditions. It achieved complete degradation of the ibuprofen parent compound, attaining an 85.9% mineralization rate. The efficacy stems from the reversible Mn³⁺/Mn⁴⁺ redox couple. The ratio of Mn³⁺/Mn⁴⁺ was 3.9 for TiO₂-modified LaMnO₃, significantly higher than 1.2 for nanocast LaMnO₃. Experimental results and density functional theory revealed that La and Ti did not actively participate in the catalytic ozone reaction. Notably, the Mn³⁺/Mn⁴⁺ pair emerged as key drivers in the involvement of HO•, O₂•⁻, and ¹O₂ in the reactive oxygen species pathway. Notably, ozone exhibited preferential adsorption and activation on the (010) crystal face of the catalyst. A moderated reduction in interaction forces facilitated the Mn³⁺/Mn⁴⁺ redox cycle, resulting in increased production of reactive oxygen species. These findings contributed to the development of more efficient catalysts for environmental remediation. Full article