Search Results (374)

The present study involves the synthesis of polyvinylpyrrolidone (PVP)-stabilized iron-based trimetallic nanoparticles with different metal addition sequences (Fe/Ag/Zn, Fe/Zn/Ag and Fe/(Zn/Ag)) using the sodium borohydride reduction method. In order to investigate the catalytic reactivity of the nanoparticles, a series of batch experiments were performed using methyl orange dye as a model pollutant. It was found that the Fe/Ag/Zn system showed the maximum catalytic activity compared to the other studied trimetallic systems. About 100% of the methyl orange dye was removed within 1 min and the second-order rate constant obtained was 0.0744 (mg/L)⁻¹ min⁻¹; the rate of reaction was higher than that of the other trimetallic systems. Furthermore, the effects of pH, initial dye concentration and nanoparticle dosage on the degradation of methyl orange were investigated. The results showed that the reactivity of the Fe/Ag/Zn trimetallic nanoparticles was highly dependent on the aforementioned parameters. Higher reactivity was obtained at lower pH, lower initial methyl orange dye concentration and higher nanoparticle dosage. Lastly, liquid chromatography–mass spectroscopy (LC-MS) was used to elucidate the reaction pathway and identify by-products from methyl orange degradation. The developed catalyst demonstrated exceptionally rapid and apparent degradation of methyl orange within one minute, outperforming previously reported bimetallic and trimetallic systems. This work reports a cost-effective nZVI-based trimetallic system containing minimal silver, which shows promising reactivity toward azo dye degradation and may be suitable for future application in textile wastewater treatment. Full article

The simultaneous stabilization of Cu, Ni, Pb, and As in sustainable environmental development remains a significant challenge in heavy metal remediation. In this paper, liquid phase equilibrium experiments have evaluated the immobilization efficiency of 20 potential stabilization materials. Soil stabilization experiments, material characterization, and long-term effectiveness assessments have been performed to investigate the efficient composite stabilization agent and its underlying mechanisms. Results demonstrate that seven materials, including calcium oxide (CaO) and hydroxyapatite (HAP), exhibit multi-metal immobilization capabilities. Among single-material stabilization in soil, HAP for Pb, zero-valent iron (ZVI) for As, and blast furnace slag (BFS) for Cu exhibit prominent stabilization efficiency, yet they cannot efficiently stabilize the four heavy metals simultaneously. Subsequently, the ZVI:BFS:CaO composite agent (6:3:1 mass ratio, 10% addition rate) has been proposed by formulation optimization, achieving remarkable stabilization rates: 99.92% for Cu, 96.16% for Ni, 92.06% for Pb, and 99.58% for As. XRD, XPS, and SEM-EDS analyses confirm that the stabilization occurs through synergistic mechanisms including precipitation, complexation, and lattice encapsulation. The composite stabilizing agent withstood 15 wet–dry and 150 freeze–thaw cycles, with four types of heavy metals stabilization rates > 60%, confirming its long-term effectiveness. Full article

Advanced oxidation processes (AOPs) are increasingly used for the remediation of soils contaminated with petroleum hydrocarbons, as they rapidly mineralize recalcitrant fractions to CO₂ and H₂O. However, the effects of AOPs on the geotechnical properties of such soils remain not well understood. In this study, the influences of a combined oxidation system of sodium percarbonate (SPC), nanoscale zero-valent iron (nZVI), and sodium persulfate (PS) on the geotechnical behavior of petroleum hydrocarbon-contaminated soil were investigated. A series of tests, including basic geotechnical index, pH, Atterberg limits, particle size distribution, and consolidated undrained triaxial compression test, were conducted to explore the geotechnical responses and underlying mechanisms associated with the dual AOPs treatment. The results indicate that the diesel-contaminated soil exhibited slightly higher LL and PI compared with the natural soil. For the treated soils, LL and PI remained essentially unchanged with increasing SPC dosage. The particle-size distribution first migrated to finer fractions and then reverted to a coarser mode. The strongest fining was observed at 2% SPC, whereas higher SPC dosages induced aggregation and the formation of larger agglomerates. Consolidated undrained triaxial tests indicate that diesel contamination reduced undrained stiffness and strength. The nZVI–PS treatment without SPC produced a partial recovery in stiffness and a slight increase in the friction angle. With increasing SPC dosage, the soils exhibited a nonmonotonic response in stiffness and shear strength, where low SPC enhanced apparent cohesion and higher SPC weakened bonds while partially restoring frictional resistance. These findings suggest that advanced oxidation of petroleum hydrocarbon–contaminated soils requires a trade-off. This trade-off is between contaminant degradation efficiency and the preservation of geotechnical performance to ensure the reuse of the remediated soil. Full article

This work optimizes the energetic performance of 2,4,6-trinitrotoluene (TNT) abatement in water using a sono-photo-Fenton-like (SPF) process coupled with nano zero-valent iron (nZVI). A response–surface methodology (RSM) with a five-level central composite design (CCD) was applied to concurrently minimize specific energy consumption (SEC) from ultrasound (US) and UV irradiation while maximizing TNT removal. The optimal conditions were US power 80 W for 2 min and UV power 10 W for 6 min, yielding 73.95% TNT removal with SEC = 101.19 kWh kg⁻¹ TNT removed. The analysis of variance (ANOVA) test revealed that US power had the greatest effect on removal efficiency, whereas UV and US exposure times predominantly influenced SEC. Relative to the other Fenton-like configurations examined, the optimized SPF achieved superior removal at lower SEC and enabled enhanced iron recovery compared with photo-Fenton process using Fe²⁺. When applied to actual “yellow” wastewater, the optimized SPF again outperformed the photo-Fenton process using Fe²⁺, reducing SEC from 380.77 to 252.60 kWh kg⁻¹ and increasing treatment efficiency. The high-power/short-duration US paired with a low-power/short-duration UV regime provides a favorable efficacy–energy trade-off and supports pilot-scale deployment. Full article

Amorphous nano zero-valent iron (A-nZVI) was synthesized via liquid-phase reduction and ethylenediamine (EDA) modification to enhance trichloroethylene (TCE) dechlorination. A-nZVI showed a cauliflower-like morphology, where 20–50 nm primary particles formed 500–1000 nm secondary agglomerates with a high surface area. Compared with crystalline nZVI (C-nZVI), A-nZVI exhibited higher electron transfer efficiency and stronger reducing capability (potentiodynamic polarization analysis). TCE removal followed a two-stage model: a rapid adsorption–reduction phase (pseudo-second-order; q_e = 9.48 mg/g, R² = 0.998) and a slower degradation phase (pseudo-first-order; k = 0.0125 h⁻¹, R² = 0.994). No toxic intermediates (e.g., dichloroethylene or vinyl chloride) were detected; products were mainly acetylene, ethylene, and ethane. The electron utilization efficiency increased from 8.47% (C-nZVI) to 15.32% (A-nZVI), while hydrogen evolution decreased by 32%. EDA formed Fe–N coordination bonds that facilitated electron transfer and stabilized the amorphous structure. A-nZVI retained 40% of its activity after four cycles under neutral to alkaline conditions. Full article

Caproate is a valuable medium-chain fatty acid (MCFA) that is found to be extensively used in biofuel production, food preservation, and the pharmaceutical industries. Short-chain fatty acids (SCFAs) from waste streams can be upgraded sustainably through their biological synthesis via anaerobic chain elongation. However, caproate production is frequently limited in real-world systems due to low carbon conversion efficiency and a lack of electron donors. In this study, we developed a two-stage fermentation strategy employing yellow water—a high-strength organic wastewater from liquor manufacturing—as a novel substrate. During primary fermentation, Lactobacillus provided endogenous electron donors by converting the residual carbohydrates in the yellow water into lactic acid. Nano zero-valent iron (NZVI) was introduced to the secondary fermentation to enhance power reduction and electron flow, further promoting caproate biosynthesis. The caproate production increased significantly due to the synergistic action of lactic acid and NZVI, reaching a maximum concentration of 20.41 g·L⁻¹ and a conversion efficiency of 69.50%. This strategy enhances carbon recovery and electron transport kinetics while lowering dependency on expensive external donors like hydrogen or ethanol. Microbial community analysis using 16S rRNA sequencing revealed enrichment of chain-elongating bacteria such as Clostridium kluyveri. These findings demonstrate the feasibility of employing an integrated fermentation–electron management technique to valorize industrial yellow water into compounds with added value. This study offers a scalable and environmentally sound pathway for MCFA production from waste-derived resources. Full article

The textile industry releases effluents containing toxic contaminants such as azo dyes, which severely affect water quality and aquatic ecosystems. This study optimized the Fe⁰/H₂O₂/UV photo-Fenton process through Response Surface Methodology (RSM) using a Box–Behnken design applied to real textile wastewater. The process relies on in situ hydroxyl radicals (•OH) generation, which degrades refractory organic compounds. Under optimal conditions (pH 3.5, 0.5 g Fe⁰, and 0.55 mL H₂O₂), the system achieved complete color removal, 91% aromatic structures degradation, and an 80% COD reduction within 3 h. Statistical validation indicated an excellent model fit (R² = 1.0; Q² = 1.0), with strong correlation between experimental and predicted results. Spectroscopic analyses (UV–Vis and FTIR) further confirmed the cleavage of chromophoric and aromatic structures, indicating efficient pollutant degradation. Overall, the findings indicate that the Fe⁰/H₂O₂/UV system is an effective and sustainable technology for treating textile wastewater, offering strong potential for industrial-scale application. Full article

The agrifood sector produces considerable waste, offering opportunities for sustainable innovation. In the coffee industry, spent coffee grounds (SCG) can be valorized to generate eco-friendly nanomaterials such as nano zerovalent iron (nZVI), widely applied in soil and water remediation. In this study, green nZVIs were synthesized using SCG hydromethanolic extracts and FeCl₃, subsequently characterized, and assessed for cytotoxicity. High-performance liquid chromatography with diode-array detection (HPLC-DAD) was employed to identify hydroxycinnamic acids, caffeine, and trigonelline in the SCG extracts. Preliminary remediation assays were conducted with seven contaminants, with venlafaxine selected for detailed pH and kinetic studies. Characterization of nZVIs included SEM and EDS analyses, which revealed spherical nZVI particles (72–83 nm) composed of carbon (47%), oxygen (34%), and iron (16%). Dynamic light scattering (DLS) measurements indicated the presence of smaller particles (15–23 nm). Thermogravimetric analysis (TG) confirmed a residual mass of about 20% at 1400 °C. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed phenolic compound incorporation, while X-ray diffraction (XRD) revealed an amorphous structure. The particles exhibited magnetic behavior and showed no cytotoxicity toward MRC-5 and U87 cell lines. Among the tested contaminants, venlafaxine displayed the highest removal efficiency in remediation tests. Compared with chemically synthesized nZVI, the green version exhibited enhanced stability, attributed to the presence of surface-bounded organic matter. Overall, this sustainable and cost-effective approach to produce nZVI from SCG provides an innovative method for waste valorization and environmental remediation. Full article

Rice (Oryza sativa L.) exhibits a heightened ability to bioaccumulate arsenic (As) and cadmium (Cd), which directly affects the quality of agricultural products and poses serious risks to both the ecological environment and human health. Due to considerable differences in the occurrence states and chemical behaviors of As and Cd, simultaneous remediation efforts for water or soil contaminated by these elements often prove challenging. Our previous study indicated that the addition of both As and Cd markedly promoted the immobilization of each other by sulfidized nano-zero-valent iron (S-nZVI). To further explore the influence of S-nZVI on the passivation of As-Cd composite contamination, we examined its effect on the residual proportions of As and Cd in the soil by varying the dosage of S-nZVI, the soil moisture content and pH levels. At 2 g·kg⁻¹ S-nZVI over a 90-day period, residual fraction reached 83% for As and 39% for Cd. When the water content was 100%, residual fractions peaked at 83% for As and 29% for Cd. Additionally, variations in initial pH levels were found to have no significant impact on the remediation efficiency of As and Cd. This suggests that S-nZVI has the ability to sustain the stabilization of As and Cd in soil across diverse environmental conditions. The evident passivation effects on As-Cd composite contaminated soil can effectively reduce the potential ecological risk associated with these contaminants. Full article

In this work, two novel nanoscale zero-valent iron (nZVI) composites (nanoscale zero-valent iron and copper-intercalated montmorillonite (MMT-nFe⁰/Cu⁰) and carbon microsphere-supported sulfurized nanoscale zero-valent iron (CMS@S-nFe⁰)) were used to treat soil contaminated with both Cr(VI) and p-nitrophenol (PNP), and added persulfate (PMS). Experiments found that the pollutant removal effect has a great relationship with the ratio of water to soil, the amount of catalyst, the amount of PMS, and the pH value. When the conditions are adjusted to the best (water–soil = 2:1, catalyst 30 g/kg, PMS 15 g/kg, pH 7–9), both materials fix Cr(VI) well and decompose PNP. The removal rates of Cr(VI) and PNP by the MMT-nFe⁰/Cu⁰ system are 90.4% and 72.6%, respectively, while the CMS@ S-nFe⁰ system is even more severe, reaching 94.8% and 81.3%. Soil column leaching experiments also proved that the fixation effect of Cr can last for a long time and PNP can be effectively decomposed. Through detection methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), we found that Cr(VI) was effectively reduced to Cr(III) by Fe⁰ and Fe²⁺ ions and subsequently transformed into stable FeCr₂O₄ spinel oxides, and the groups produced after the decomposition of PNP could also help fix the metal. This work provides a way to simultaneously treat Cr(VI) and PNP pollution, and also allows the use of multifunctional nZVI composites in complex soil environments. Full article

Iron-based catalysts for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation represent a cornerstone of advanced oxidation processes (AOPs) in environmental remediation, prized for their cost-effectiveness, environmental compatibility, and high catalytic potential. These catalysts, including zero-valent iron, iron oxides, and iron-organic frameworks, activate PMS/PDS through heterogeneous and homogeneous pathways to generate reactive species such as sulfate radicals (SO₄•⁻) and hydroxyl radicals (•OH). However, their large-scale implementation is constrained by inefficient iron cycling, characterized by sluggish Fe³⁺/Fe²⁺ conversion and significant iron precipitation, leading to catalyst passivation and oxidant wastage. This comprehensive review systematically dissects innovative strategies to augment iron cycling efficiency, encompassing advanced material design through elemental doping, heterostructure construction, and defect engineering; system optimization via reductant incorporation, bimetallic synergy, and pH modulation; and external field assistance using light, electricity, or ultrasound. We present a mechanistic deep-dive into these approaches, emphasizing facilitated electron transfer, suppression of iron precipitation, and precise regulation of radical versus non-radical pathways. The performance in degrading persistent organic pollutants—including antibiotics, per- and polyfluoroalkyl substances (PFASs), and pesticides—in complex environmental matrices is critically evaluated. We further discuss practical challenges related to scalability, long-term stability, and secondary environmental risks. Finally, forward-looking directions are proposed, focusing on rational catalyst design, integration of sustainable processes, and scalable implementation, thereby providing a foundational framework for developing next-generation iron-persulfate catalytic systems. Full article

To address the issues of zero-valent iron Fe(0) passivation and limited nitrogen and phosphorus removal in constructed wetlands (CWs), this study investigated the enhancement effect of two carbon materials—activated carbon (AC) obtained through high-temperature pyrolysis and biochar (BC) obtained through low-temperature pyrolysis—when coupled with Fe(0). Four systems were set up: control (CW-C), Fe(0) alone (CW-Fe), Fe(0) with AC (CW-FeAC), and Fe(0) with BC (CW-FeBC). Evaluations covered wastewater treatment performance, microbial community structure, and functional gene abundance. Results showed that iron–carbon coupling significantly improved nitrogen and phosphorus removal, with the CW-FeAC system performing best, achieving 58% total nitrogen (TN) and 90% total phosphorus (TP) removal. This enhancement was attributed to AC’s high conductivity, which strengthened iron–carbon micro-electrolysis, accelerated Fe(0) corrosion, and enabled continuous Fe²⁺/Fe³⁺ release, supplying electrons for denitrification and phosphorus precipitation. Microbial analysis indicated that iron–carbon coupling markedly reshaped community structure, enriching key genera such as Thiobacillus (33.8%) and Geobacter (12.5%) in CW-FeAC. Functional gene analysis further confirmed higher abundances of denitrification (napA/narG→nirS→nosZ) and iron metabolism genes (feoA/feoB), suggesting enhanced nitrogen-iron cycling. This study clarifies the mechanisms by which iron–carbon coupling improves nitrogen and phosphorus performance in CWs and highlights the superiority of AC over BC in facilitating electron transfer and functional microorganism enrichment, providing a basis for the design of enhanced CW systems treating low-carbon-nitrogen-ratio wastewater, such as secondary effluent or lightly polluted surface water. Full article

The bloom of cyanobacteria has severely disrupted ecological balances, posing significant risks to human health and safety. However, there is currently a lack of environmentally friendly methods that can sustainably suppress these blooms over the long term. This study integrates untargeted metabolomics, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) to systematically characterize the responses of Microcystis aeruginosa to nano zero-valent iron (nZVI). Exposure to nZVI reprograms lipid and amino acid metabolism, coincides with the suppression of protein biosynthesis, and perturbs central pathways—including the tricarboxylic acid (TCA) cycle, photosynthesis, and carbohydrate metabolism—leading to disruptions in energy balance and metabolic homeostasis. FTIR and SEM provide complementary evidence of membrane compromise, with attenuation of -OH, -C-H, and C=O functional group signals, abnormal cell morphology, and progressive oxidative injury culminating in cell lysis and solute leakage. Together, these results support the inhibitory effect of nZVI on M. aeruginosa and provide insights to guide metabolomics studies of M. aeruginosa using nZVI. Full article

This study presents a comprehensive bibliometric analysis of 217 publications on nanomaterials for soil and groundwater remediation, sourced from the Scopus database, covering the period from 2010 to 2024. The findings highlight significant contributions from various countries, with India identified as the leading contributor, followed by China and the United States. This reflects robust international collaboration in addressing environmental contamination. The analysis also identifies influential journals in this field, particularly “Science of the Total Environment” and “Environmental Science and Technology”, which are recognized for their high citation impact and play a crucial role in disseminating research findings and advancing knowledge in nanomaterials for environmental remediation. A keyword co-occurrence analysis reveals six distinct clusters that emphasize critical research themes. The first cluster focuses on environmental toxicity, underscoring the risks posed by contaminants, particularly heavy metals and emerging pollutants such as PFAS, highlighting the need for advanced monitoring strategies. The second cluster showcases innovative nanoremediation technologies, particularly zero-valent iron (nZVI) and carbon nanotubes (CNTs), which are noted for their effectiveness in pollutant removal despite challenges like surface passivation and high production costs. The third cluster addresses heavy metals and phytoremediation, advocating integrated strategies that enhance crop resilience while managing soil contamination. The fourth cluster explores photocatalysis and advanced oxidation processes, demonstrating how nanomaterials can enhance pollutant degradation through light-activated catalytic methods. The fifth cluster emphasizes adsorption mechanisms for specific contaminants, such as arsenic and pharmaceuticals, suggesting targeted remediation strategies. Finally, the sixth cluster highlights the potential of nanomaterials in agriculture, focusing on their role in improving soil fertility and supporting plant growth. Overall, while nanomaterials demonstrate significant potential for effective environmental remediation, they also pose risks that necessitate careful consideration and further research. Future studies should prioritize optimizing these materials for practical applications, addressing both environmental health and agricultural productivity. Full article

In this study, the use of spent coffee waste as a green precursor of polyphenolic compounds, which are subsequently employed as reducing agents for the synthesis of zero-valent iron nanoparticles (nZVI) aimed at the efficient removal of dyes from aqueous systems, has been investigated. The nanoparticles, generated in situ in the presence of controlled amounts of hydrogen peroxide, were applied in the removal of organic dyes—including methylene blue, methyl orange, and orange G—through a heterogeneous Fenton-like catalytic process. The synthesized nZVI were thoroughly characterized by nitrogen adsorption at 77 K, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (XRD). A statistical design of experiments and response surface methodology were employed to evaluate the effect of polyphenol, Fe(III), and H₂O₂ concentrations on dye removal efficiency. Results showed that under optimized conditions, a 100% removal efficiency could be achieved. This work highlights the potential of nZVI synthesized from agro-industrial waste through sustainable routes as an effective solution for water remediation, contributing to circular economy strategies and environmental protection. Full article