Search Results (657)

Persistent reactive azo dyes released from textile finishing are a serious threat to water systems, but effective methods using sunlight to break them down are still limited. Everzol Yellow 3RS (EY-3RS) is particularly recalcitrant: past studies have relied almost exclusively on physical adsorption onto natural or modified clays and zeolites, and no photocatalytic pathway employing engineered nanomaterials has been documented to date. This study reports the synthesis, characterization, and performance of a visible-active ternary nanocomposite, Cu₄O₃/ZrO₂/TiO₂, prepared hydrothermally alongside its binary (Cu₄O₃/ZrO₂) and rutile TiO₂ counterparts. XRD, FT-IR, SEM-EDX, UV-Vis, and PL analyses confirm a heterostructured architecture with a narrowed optical bandgap of 2.91 eV, efficient charge separation, and a mesoporous nanosphere-in-matrix morphology. Photocatalytic tests conducted under midsummer sunlight reveal that the ternary catalyst removes 91.41% of 40 ppm EY-3RS within 100 min, markedly surpassing the binary catalyst (86.65%) and TiO₂ (81.48%). Activity trends persist across a wide range of operational variables, including dye concentrations (20–100 ppm), catalyst dosages (10–40 mg), pH levels (3–11), and irradiation times (up to 100 min). The material retains ≈ 93% of its initial efficiency after four consecutive cycles, evidencing good reusability. This work introduces the first nanophotocatalytic strategy for EY-3RS degradation and underscores the promise of multi-oxide heterojunctions for solar-driven remediation of colored effluents. Full article

This study focuses on the exchange of mono- and divalent metal cations in FAU-type zeolite and their behavior in gas-phase CO₂ adsorption measurements and liquid-phase methylene blue (MB) adsorption in the absence of oxidizing agents under dark conditions. Firstly, zeolites exchanged with different cations were characterized by several techniques, such as XRD, SEM, XRF, XPS, and N₂ adsorption–desorption, to reveal the impact of the cations on the zeolite texture and structure. The adsorption studies revealed a positive effect of cation exchange on the adsorption capacity of the zeolite, particularly for silver-loaded FAU zeolite. In liquid-phase experiments, Ag-Y zeolite also demonstrated the highest MB removal, with a value of 79 mg/g. Kinetic studies highlighted that Ag-Y could reach the MB adsorption equilibrium within 1 h, with its highest rate of adsorption occurring during the first 5 min. In gas-phase adsorption studies, the highest CO₂ adsorption capacity was also achieved over Ag-Y, yielding 10.4 µmol/m² of CO₂ captured. Full article

This study examined a strategy for effective reject water treatment involving hydrodynamic cavitation (HC) combined with subsequent adsorption using natural zeolites. Two experiments were conducted: The first involved the selection of optimal pre-treatment conditions of HC for biodegradability and to reduce the ammonium nitrogen and phosphate content. Three inlet pressures of 3, 5, and 7 bar and two types of cavitation inducers, i.e., multiple- and single-hole orifice plates, were evaluated. Adsorption experiments were conducted in batch mode using natural zeolite, and three doses of zeolite (50, 100, and 200 g/L) and six contact times (4–24 h) were examined. In the HC experiments, the application of 3 bar pressure, a single-hole cavitation inducer, and a cavitation time of 30 min resulted in the removal of ammonia nitrogen and phosphates amounting to 26.5 and 23%, respectively. In this case, 3.6-fold enhancement in the biodegradability index was also found. In the second experiment, the use of zeolite led to a decrease in the remaining content of both ammonia nitrogen and phosphates, improving the chemical oxygen demand-to-total nitrogen ratio. The highest removal efficacy was found for the highest zeolite dose of 200 g/L and the longest cavitation time of 24 h. Under these conditions, the ammonia nitrogen and phosphate removal rates were 70 and 94%, respectively. Full article

This paper presents the results of an investigation into the catalytic activity and selectivity of rhodium-based catalysts supported on natural zeolite clinoptilolite from the Shankanai field (Kazakhstan) in the dehydrogenation of light alkanes from associated petroleum gas (APG). Three modifications of the catalyst have been studied: basic 1%Rh/HCpt, modified with tin 1%Rh/10%SnO/HCpt, and combined with additives of tin and potassium 1%Rh/10%SnO/5%K₂O/HCpt. It has been shown that the addition of tin contributes to increased thermal stability and a decreased coking rate, while the addition of potassium suppresses side reactions (cracking and isomerization), increasing the selectivity for olefins. The highest yield of olefins (~30%) is achieved with the 1%Rh/10%SnO/5%K₂O/HCpt catalyst in the presence of water vapor. Using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), improved distribution of active components and reduced catalyst deactivation have been confirmed. The obtained data demonstrate the potential of the developed systems for the efficient processing of APG and the selective synthesis of olefins. Full article

Biodiesel, a renewable and environmentally friendly alternative to fossil fuels, has attracted significant attention due to its potential to reduce greenhouse gas emissions. However, high production costs and complex processing remain challenges. Heterogeneous catalysts have shown promise in overcoming these barriers by offering benefits, such as easy separation, reusability, low-cost raw materials, and the ability to reduce reaction times and energy consumption. This review evaluates key classes of heterogeneous catalysts, such as metal oxides, ion exchange resins, and zeolites, and their performance in transesterification and esterification processes. It highlights the importance of catalyst preparation methods, textural properties, including surface area, pore volume, and pore size, activation techniques, and critical operational parameters, like the methanol-to-oil ratio, temperature, time, catalyst loading, and reusability. The analysis reveals that catalysts supported on high surface area materials often achieve higher biodiesel yields, while metal oxides derived from natural sources provide cost-effective and sustainable options. Challenges, such as catalyst deactivation, sensitivity to feedstock composition, and variability in performance, are discussed. Overall, the findings underscore the potential of heterogeneous catalysts to enhance biodiesel production efficiency, although further optimization and standardized evaluation protocols are necessary for their broader industrial application. Full article

This study systematically compares the environmental and economic performance of three wastewater treatment systems: constructed wetlands (CWs), microbial fuel cells (MFCs), and their integration (CW–MFC). Lab-scale units of each system were constructed using a multi-media matrix (gravel, zeolite, and granular activated carbon), composite native wetland species (Juncus effusus, Iris sp., and Typha angustifolia), carbon-based electrodes (graphite), and standard inoculum for CW and CW–MFC. The MFC system employed carbon-based electrodes and proton-exchange membrane. The experimental design included a parallel operation of all systems treating domestic wastewater under identical hydraulic and organic loading rates. Environmental impacts were quantified across construction and operational phases using life cycle assessment (LCA) with GaBi software 9.2, employing TRACI 2021 and ReCiPe 2016 methods, while techno-economic analysis (TEA) evaluated capital and operational costs. The key results indicate that CW demonstrates the lowest global warming potential (142.26 kg CO₂-eq) due to its reliance on natural biological processes. The integrated CW–MFC system achieved enhanced pollutant removal (82.8%, 87.13%, 78.13%, and 90.3% for COD, NO₃, TN, and TP) and bioenergy generation of 2.68 kWh, balancing environmental benefits with superior treatment efficiency. In contrast, the stand-alone MFC shows higher environmental burdens, primarily due to energy-intensive material requirements and fabrication processes. TEA results highlight CW as the most cost-effective solution (USD 627/m³), with CW–MFC emerging as a competitive alternative when considering environmental benefits and operational efficiencies (USD 718/m³). This study highlights the potential of hybrid systems, such as CW–MFC, to advance sustainable wastewater treatment technologies by minimizing environmental impacts and enhancing resource recovery, supporting their broader adoption in future water management strategies. Future research should focus on optimizing materials and energy use to improve scalability and feasibility. Full article

Implementing efficient strategies for the circular recovery and reuse of nutrients from wastewaters is mandatory to meet the Green Deal objectives and Sustainable Development Goals. In this context we investigated the use of zeolitic tuff (containing chabazite and phillipsite) in the selective recovery and reuse of N from various anaerobic liquid digestates in view of their implementation in farm-scale treatment plants. We tested the method on three livestock digestates and two municipal organic solid waste digestates. Adsorption isotherms and kinetics were assessed on each digestate, and a large set of parameters, including (i) contact time, (ii) initial NH₄⁺ concentration, (iii) presence of competing ions, (iv) total solids content, and (vi) separation methods (microfiltration and clarification), were considered in the experimental design. Our results showed that the adsorption mechanism can be explained by the Freundlich model (R² up to 0.97), indicating a multilayer and heterogeneous adsorption, while the kinetic of adsorption can be explained by the pseudo-second-order model, indicating chemical adsorption and ion exchange. The efficiency in the removal of NH₄⁺ was indirectly related to the K⁺ and total solids content of the digestate. Maximum NH₄⁺ removal exceeded 90% in MSW-derived digestates and 80% within 60 min in livestock-derived digestates at a 5% solid/liquid ratio. Thermodynamic parameters confirmed favorable and spontaneous adsorption (ΔG up to −7 kJ⋅mol⁻¹). Farm-scale projections estimate a nitrogen recovery potential of 1.2 to 16 kg N⋅day⁻¹, depending on digestate type and process conditions. These findings support the application of natural zeolitic tuffs as a low-cost, chemical-free solution for ammonium recovery, contributing to sustainable agriculture and circular economy objectives. Full article

In this study, aligned with the principles of the circular economy and sustainability, novel eugenol@natural zeolite (EG@NZ) and citral@natural zeolite (CT@NZ) nanohybrids were developed. These nanohybrids were successfully incorporated into a pork gelatin (Gel)/glycerol (Gl) composite matrix using an extrusion–compression molding method to produce innovative active packaging films: Gel/Gl/xEG@NZ (where x = 5, 10, and 15%wt.) and Gel/Gl/xCT@NZ (where x = 5 and 10%wt.). All films exhibited zero oxygen barrier properties. Release kinetic studies showed that both EG@NZ and CT@NZ nanohybrids adsorbed up to 58%wt. of their respective active compounds. However, EG@NZ exhibited a slow and nearly complete release of eugenol, whereas CT@NZ released approximately half of its citral content at a faster rate. Consequently, the obtained Gel/Gl/xEG@NZ films demonstrated significantly higher antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazylradical (DPPH) assay and superior antibacterial effectiveness against Escherichia coli and Listeria monocytogenes compared to their CT-based counterparts. Overall, the Gel/Gl/xEG@NZ films show strong potential for applications as active pads for fresh pork ham slices, offering zero oxygen permeability, enhanced antioxidant and antibacterial properties, and effective control of total viable count (TVC) growth, maintaining a low and steady rate beyond the 10th day of a 26-day storage period. Full article

Edible oils undergo undesirable changes over time or during thermal treatment due to enzymatic, microbial, and chemical processes, leading to spoilage. In this study, the oxidative state of sunflower oil was assessed by determining the peroxide value (PV), anisidine value (AV), and totox value (TV) using standard methods. The oil was heated at temperatures ranging from 110 to 190 °C for 10 and 30 min, also in the presence of molecular sieves (zeolite 4A, clinoptilolite, and bentonite). When using the synthetic molecular sieve zeolite 4A, a reduction in the totox value by 35.72% was observed. When natural molecular sieves were used, a reduction of 33.19% was recorded for clinoptilolite, while for bentonite, the reduction was 31.08%. Both natural and synthetic molecular sieves demonstrated a strong ability to regenerate thermally treated oils. Full article

Particle film technology is an environmentally sustainable crop protection method, offering an alternative to chemical pesticides for disease control. Copper-based compounds have long been central to the management of bacterial and fungal diseases, particularly in organic agriculture. However, due to their environmental persistence, their use has been increasingly restricted by European regulations, making the management of widespread diseases such as Olive Knot (Pseudomonas savastanoi pv. savastanoi) and Downy Mildew (Plasmopara viticola) more difficult. The LIFE Microfighter project addresses this problem by testing a novel Zeo-Biopesticide (ZBp), in which natural zeolite serves as a carrier for the beneficial bacterium Pseudomonas synxantha DLS65. Field trials conducted in high-rainfall areas of Emilia-Romagna (Italy) evaluated the product’s distribution and persistence on olive and grape leaves through ESEM (Environmental Scanning Electron Microscopy) observations, its ability to retain the microorganism, and its effectiveness for disease control. Results showed that ZBp significantly reduced Olive Knot incidence compared to both the untreated control and Cu-based treatments (p < 0.05), supporting its potential as an alternative for bacterial disease management, while showing no statistically significant difference compared to the control in either the incidence or severity of Downy Mildew (p > 0.05). Its persistence and adherence to plant surfaces, which could influence its overall field performance, were affected by environmental conditions, particularly rainfall. Full article

Although constructed wetlands (CWs) are a viable solution for wastewater treatment, substrate selection significantly affects their performance. This study evaluated the adsorption behavior of ammonium and orthophosphate on natural zeolite (coarse- and fine-grained) and coarse gravel using kinetic and isotherm experiments. Coarse materials are intended for use as filler media in CWs to address problems such as clogging. Ammonium removal due to adsorption reached 96.20% and 96.49% for coarse and fine zeolite, respectively, and 16.84% for gravel. For orthophosphate, the removal was 11.46% and 12.81% for coarse and fine zeolite, respectively, and 6.70% for gravel. Kinetic analysis showed that the adsorption of both nutrients followed the pseudo-second-order model. Zeolite exhibited high ammonium adsorption capacities (181.87 and 174.23 mg/kg), with granulometry showing minimal effect. The orthophosphate adsorption capacities were lower (11.76 and 12.35 mg/kg for zeolite; 6.44 mg/kg for gravel). Isotherm modeling indicated that ammonium adsorption fitted better to the Langmuir model (monolayer adsorption), while orthophosphate followed the Freundlich model (heterogeneous surface adsorption). Ζeolite adsorbed six times more ammonium and twice as much phosphate as gravel. These findings suggest that natural zeolite is an effective and sustainable CW substrate, enhancing nutrient removal and serving as an economical and environmentally friendly alternative to traditional filler media. Full article

Kasugamycin (KSM) is easily affected by photolysis, acid–base destruction, and oxidative decomposition in the natural environment, leading to its poor durability and low effective utilization rate, which affects its control effect on plant bacterial diseases. Nanomaterials modified with environment-responsive agents enable the control of the release of pesticides through intelligently responding to external stimuli, thereby improving efficacy and reducing environmental impact. In this study, a pH-responsive controlled release system was constructed using zeolitic imidazolate frameworks (ZIF-93) for the sustained and targeted delivery of KSM. The synthesized KSM@ZIF-93 exhibited a diameter of 63.93 ± 11.19 nm with a drug loading capacity of 20.0%. Under acidic conditions mimicking bacterial infection sites, the Schiff base bonds and coordination bonds in ZIF-93 dissociated, triggering the simultaneous release of KSM and Zn²⁺, achieving a synergistic antibacterial effect. Light stability experiments revealed a 34.81% reduction in UV-induced degradation of KSM when encapsulated in ZIF-93. In vitro antimicrobial assays demonstrated that KSM@ZIF-93 completely inhibited Erwinia amylovora at 200 mg/L and had better antibacterial activity and persistence than KSM and ZIF-93. The field experiment and safety evaluation showed that the control effect of KSM@ZIF-93 on pear fire blight at the concentration of 200 mg/L was (75.19 ± 3.63)% and had no toxic effect on pollen germination. This pH-responsive system not only enhances the stability and bioavailability of KSM but also provides a targeted and environmentally compatible strategy for managing bacterial infections during the flowering period of pear trees. Full article

Chabazite, a tectosilicate mineral, belongs to the zeolite group and has been widely used for the adsorptive removal of a number of cationic contaminants from the aqueous phase. However, a negatively charged chabazite surface can be altered by chemical modification in order to change its adsorption abilities towards anions. This study reports the potential for the removal of hexavalent chromium ions from aqueous solutions by modified chabazite. In this regard, natural chabazite was modified by the immobilization of HDTMA-Br to achieve double-layer coverage on its surface, defined as the double external cation exchange capacity. Next, a batch adsorption system was applied to study the adsorption of inorganic Cr(VI) anions from aqueous solutions. The process equilibrium was described by 11 theoretical isotherm equations, while 6 adsorption kinetics were represented by four models. Among those tested, the most appropriate model for the description of the studied process kinetics was the pseudo-second order irreversible model. The obtained results suggest that Cr(VI) adsorption takes place according to a complex mechanism comprising both Langmuir-type sorption with the maximum adsorption capacity of modified chabazite, approx. 9.3–9.9 mg g⁻¹, and the trapping of Cr(VI) inside the capillaries of the amorphous sorbent, making it a viable option for water treatment applications. Full article

Materials derived from metal–organic frameworks (MOFs) as MOF-derived oxides retain a highly porous and active structure from the MOF precursor, exhibiting excellent sensing properties. In addition, the tunable nature of MOFs allows the structural and chemical properties of the resulting oxides to be specifically tuned to enhance their performance as sensing materials. In this work, zinc-based MOF structures belonging to the family of zeolitic imidazolate frameworks (ZIFs) were synthesized, characterized and then subjected to a high-temperature calcination process to obtain the corresponding oxides. To improve sensing performance, various silver doping strategies (1 wt.%) were explored, specifically through a growth process and an impregnation process. Among these approaches, the oxide obtained via the growth process demonstrates superior performance, exhibiting a response 5.8 times higher than pristine ZnO when exposed to 80 ppm of ethanol at 300 °C in a humidity-controlled chamber. These results highlight the potential of silver doping via growth process as an effective strategy to enhance the sensing performance of MOF-derived ZnO. Full article

This study focuses on the production and characterization of activated carbons derived from the carbonaceous residue obtained through the catalytic pyrolysis of waste tires. A catalytic pyrolysis process was conducted at 450 °C and 575 °C, employing two zeolitic catalysts, the commercial ZSM-5 and a synthesized zeolite (PZ2), developed from natural pozzolan, which played a key role in the pyrolysis performance and the quality of the resulting carbons. After pyrolysis, the solid residues were chemically activated using KOH to improve their porous structure and surface characteristics. Comprehensive characterization was carried out, including textural properties (BET surface area and porosity) and morphological (SEM) analysis of the activated carbons, as well as crystallinity evaluation (XRD) of the zeolitic catalysts. The BET surface areas of activated carbons PZ2-T1-AK and PZ2-T2-AK reached 608.65 m²/g and 624.37 m²/g, respectively, values that surpass those reported for similar materials under comparable activation conditions. The developed porous structure suggests strong potential for applications in adsorption processes, including pollutant removal. These findings demonstrate the effectiveness of zeolite-catalyzed pyrolysis, particularly using PZ2, as a sustainable strategy for transforming tire waste into high-performance adsorbent materials. This approach supports circular economy principles through innovative waste valorization and offers a promising solution to an environmental challenge. Full article