Search Results (139)

There is an urgent need to develop sustainable approaches for the remediation of contaminated soil as well as to promote sustainable practices for waste management. Here, we provide the first evaluation of the performance of two types of iron nanoparticles (NA and NH) obtained from olive mill wastewater for the remediation of an acidic multi-contaminated soil, including metal(loid)s, PCBs, and a flame retardant (TCPP). Their efficiency was then compared against that of a commercial nanoscale zero-valent iron (NS) through a one-month microcosm experiment employing two doses of each nanomaterial. The impact of the treatments on key soil physicochemical properties, metal(loid) availability, PCB and TCPP concentrations, and soil phytotoxicity was assessed. All treatments reduced soil acidity. Regarding organic contaminants, bioremediation of TCPP was enhanced by all nanomaterials, particularly NH, whereas NA was the only treatment that significantly reduced PCB concentration under the tested conditions. NS achieved the highest rates of metal(loid) immobilization (63–100%); NH was most beneficial for soil fertility and immobilized As, Ni, and Pb (100, 38, and 53%, respectively), whereas NA was only effective for Pb (21–49%). The low dose of both NA and NH improved the germination index (66 and 61%, respectively), reducing soil phytotoxicity. These results highlight the potential of valorizing olive mill wastewater for soil remediation, thereby contributing to the principles of the Circular Economy. Full article

Phenolic compounds are widespread environmental contaminants whose removal from water and wastewater is essential for ecosystem protection. Among the several purification technologies, the use of zero-valent metals has gained increasing interest in recent years. The identification of effective and environmentally friendly materials is a key issue for the development of this technology. In this study, zero-valent magnesium (ZVMg), a highly reactive non-toxic material, was used for the first time for the degradation of gallic acid (GA), chosen as a model phenolic compound, in an aqueous system. Several tests were conducted in order to identify the effect of pH, ZVMg amount, and temperature on the process performance. Moreover, the reusability of the reactive material in subsequent treatment cycles was assessed. Optimal operational conditions were achieved with a ZVMg amount of 0.3 g, corresponding to a ratio of 0.33 g_GA/g_Mg, reaching a removal efficiency of almost 90% in about 180 min. The performance was clearly favored by an alkaline environment, and yields close to the maximum values were reached under uncontrolled pH conditions. The increase in temperature significantly accelerated the reaction rate, which followed pseudo-first-order kinetic law, achieving high abatement percentages with a reduced quantity of ZVMg. Finally, Mg⁰ demonstrated good reusability, maintaining high efficiency, close to 78%, for up to four cycles, with the possibility of restoring the material’s activity through acid washing. The detected results confirm that ZVMg is a promising and sustainable reactive material for environmental remediation processes, offering an effective alternative for the treatment of water contaminated by phenolic compounds. Full article

The role of the metal valence state on the surface properties of metal-loaded clay minerals in the adsorption/oxidative degradation of an antibiotic was investigated. Transitional metal cations and their zero-valent counterparts such as Fe⁰, Ni⁰, Co⁰ and Cu⁰ supported on montmorillonite were comparatively investigated for their interactions during adsorption and toxicity tests of antibiotic norfloxacin (NOF). UV-Vis spectrophotometric and Fourier transform infrared (FTIR) spectroscopic analyses confirmed the involvement of the hydroxyl and carboxyl groups and/or piperazinyl nitrogen of NOF in the complexation with metal cations. Ecotoxicological assessment using aquatic plants Lemna minor showed that the metal cations reduce the bioavailability of the organic pollutant and that the zero-valent metals display higher toxicity due to their specific interaction with NOF and clay mineral surface. This evaluation will provide insights into potential environmental impacts of the co-occurrence of antibiotics and metals and will certainly contribute to correlating the safety of the water treatment by assessing the residual toxicity and its fluctuations. 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

High-valent metal species (iron, manganese, cobalt, copper, and ruthenium) based advanced oxidation processes (AOPs) have emerged as sustainable technologies for water remediation. These processes offer high selectivity, electron transfer efficiency, and compatibility with circular chemistry principles compared to conventional systems. This comprehensive review discusses recent advances in the synthesis, stabilization, and catalytic applications of high-valent metals in aqueous environments. This study highlights their dual functionality, not only as conventional oxidants but also as mechanistic mediators within redox cycles that underpin next-generation AOPs. In this review, the formation mechanisms of these species in various oxidant systems are critically evaluated, highlighting the significance of ligand design, supramolecular confinement, and single-atom engineering in enhancing their stability. The integration of high-valent metal-based AOPs into photocatalysis, sonocatalysis, and electrochemical regeneration is explored through a newly proposed classification framework, highlighting their potential in the development of energy efficient hybrid systems. In addition, this work addresses the critical yet underexplored area of environmental fate, elucidating the post-oxidation transformation pathways of high-valent species, with particular attention to their implications for metal recovery and nutrient valorization. This review highlights the potential of high-valent metal-based AOPs as a promising approach for zero wastewater treatment within circular economies. Future frontiers, including bioinspired catalyst design, machine learning-guided optimization, and closed loop reactor engineering, will bridge the gap between laboratory research and real-world applications. Full article

Soil degradation and pollution pose significant threats to global agricultural sustainability and food security. Conventional remediation methods are often constrained by low efficiency, high cost, and potential secondary pollution. Nanobiotechnology, an emerging interdisciplinary field, offers innovative solutions by integrating functional nanomaterials with plant–microbe interactions to advance soil remediation and sustainable agriculture. This review systematically elaborates on the mechanisms and applications of nanomaterials in soil remediation and enhanced plant stress resilience. For contaminant removal, nanomaterials such as nano-zero-valent iron (nZVI) and carbon nanotubes effectively immobilize or degrade heavy metals and organic pollutants through adsorption, catalysis, and other reactive mechanisms. In agriculture, nanofertilizers facilitate the regulated release of nutrients, thereby markedly enhancing nutrient use efficiency. Concurrently, certain nanoparticles mitigate a range of abiotic stresses—such as drought, salinity, and heavy metal toxicity—through the regulation of phytohormone balance, augmentation of photosynthetic performance, and reinforcement of antioxidant defenses. However, concerns regarding the environmental behavior, ecotoxicity, and long-term safety of nanomaterials remain. Future research should prioritize the development of smart, responsive nanosystems, elucidate the complex interactions among nanomaterials, plants, and microbes, and establish comprehensive life-cycle assessment and standardized risk evaluation frameworks. These efforts are essential to ensuring the safe and scalable application of nanobiotechnology in environmental remediation and green agriculture. 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

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

Cadmium {Cd (II)} poses a high risk to ecological security and human health due to its high toxicity, easy migration and difficult degradation. Using waste rubber seed shell biochar (RSSB) as the carrier material of nZVI may inhibit the caking oxidation of zero-valent iron and improve the removal efficiency of Cd (II) from water. Through a series of batch experiments, the adsorption mechanism of modified biochar on Cd (II) clarified that the removal effect of nano-zero-valent iron-rubber seed shell biochar (nZVI-RSSB) on heavy metals in water was better than that of RSSB. The results showed that when the dosage of complex biochar was 80 mg, the initial concentration of Cd (II) was 50 mg/L, and the solution pH was 6, the maximum adsorption capacity of nZVI-RSSB for Cd (II) reached 30.42 mg/g, compared with the RSSB of 13.32 mg/g. The adsorption kinetics model showed that chemisorption and physical adsorption existed simultaneously. The results of the in-particle diffusion model show that the adsorption process may be divided into two stages. The Langmuir competitive adsorption model was followed. Electrostatic adsorption and precipitation/co-precipitation could be the main ways for the removal of Cd (II) by composite materials. Meanwhile, the synergistic adsorption of nZVI-RSSB composites with multiple metals in actual water showed its application potential in water pollution control. Hence, the nZVI-RSSB not only successfully inhibits the caking oxidation of zero-valent iron, but also effectively improves the removal efficiency of heavy metals from water. Full article

In order to develop an efficient, environmentally friendly heavy metal ions adsorbent, the amino-modified expanded vermiculite-supported nano zero-valent iron (nZVI@PEI/EVMT) was prepared by using polyethyleneimine (PEI) as the functional reagent and expanded vermiculite (EVMT) as the carrier. The characterization results of nZVI@PEI/EVMT confirm that the PEI modification did not destroy the crystal configuration of EVMT, and when nano zero-valent iron (nZVI) was successfully loaded onto the PEI/EVMT surface, the value of saturation magnetic field was 41.5 emu/g, which could be separated from solution with magnet. The performance of Cr(VI) adsorption onto nZVI@PEI/EVMT was studied, showing that the ideal mass ratio for nZVI@PEI/EVMT was 1:1, and the removal capacity was largest when solution pH was 2. After four adsorption–desorption cycles, the adsorption amounts remained 40.1 mg/g. The Cr(VI) adsorption onto nZVI@PEI/EVMT was more consistent with a pseudo-second-order kinetics equation. Isotherm adsorption data accord with the Langmuir model, which suggests that the adsorption was the monolayer, the maximum adsorption amount was 116.2 mg/g at 30 °C and pH 2, and the adsorption was spontaneous and endothermic. It was inferred that the adsorption mechanisms included electrostatic attraction, reduction, chemical complexation, and co-precipitation. Full article

Zero-valent iron (ZVI), particularly in its nanoscale form (nZVI), is now considered a highly promising material for the remediation of toxic metal ions from polluted groundwater owing to its strong reductive potential, significant surface area, and reactive behavior. This review systematically explores the application of pristine and modified ZVI systems—including doped ZVI, bio-stabilized composites, and ZVI supported on advanced materials like MXene and nanocellulose—for effective treatment of water containing metal species like As(III/V), Hg(II), Cr(VI), and Ni(II). Emphasis is placed on understanding the underlying mechanisms, including redox reactions, surface complexation, and synergistic adsorption–reduction pathways. Key factors affecting adsorption efficiency—such as pH, temperature, ZVI dosage, and competing ions—are thoroughly analyzed, alongside adsorption kinetics and isotherm models. Modified ZVI composites exhibit enhanced stability, selectivity, and reusability, demonstrating promising performance even in complex aqueous environments. Despite significant progress, challenges such as nanoparticle passivation, limited field-scale data, and potential toxicity of byproducts remain. The review concludes by highlighting future research directions focused on improving material longevity, regeneration efficiency, selective adsorption, and integration with other advanced remediation technologies for sustainable and scalable groundwater treatment. Full article

The accumulation of heavy metal cadmium (Cd) in farmland soil in edible parts of crops seriously threatens plant growth, human health, and even the global ecological environment. Finding stabilization remediation technology is an important means to treat Cd-contaminated soil. This study comprehensively evaluated the synergistic effects of independent or combined application of biochar (BC) (10, 30 g kg⁻¹) and nano zero-valent iron (nZVI) (0.1% w/w) on soil properties and morphological and physiological traits of pakchoi (Brassica rapa L. subsp. chinensis) under Cd (1, 3 mg kg⁻¹) stress by pot experiments. It was shown that Cd toxicity negatively affected soil properties, reduced pakchoi biomass and total chlorophyll content, and increased oxidative stress levels. On the contrary, the combined application of BC (30 g kg⁻¹) and nZVI (0.1%, w/w) reduced the Cd accumulation in the shoot parts of pakchoi from 0.78 mg·kg⁻¹ to 0.11 mg·kg⁻¹, which was lower than the Cd limit standard of leafy vegetables (0.20 mg kg⁻¹) in GB 2762-2017 “National Food Safety Standard”. Compared with the control, the treatment group achieved a 61.66% increase in biomass and a 105.56% increase in total chlorophyll content. At the same time, the activities of catalase (CAT) and superoxide dismutase (SOD) increased by 34.86% and 44.57%, respectively, and the content of malondialdehyde (MDA) decreased by 71.27%. In addition, the application of BC alone (30 g·kg⁻¹) increased the soil pH value by 0.43 units and the organic carbon (SOC) content by 37.82%. Overall, the synergistic effect of BC (30 g kg⁻¹) and nZVI (0.1% w/w) helped to restore soil homeostasis and inhibit the biotoxicity of Cd, which provided a new option for soil heavy metal remediation and crop toxicity mitigation. Full article

To address the challenges of environmental adaptability and passivation in nanoscale zero-valent iron (nFe⁰) systems, we developed oxalate-modified nFe⁰ (nFe_oxa) through a coordination-driven synthesis strategy, aiming to achieve high-efficiency Cr(VI) removal with improved stability and reusability. Structural characterization (STEM and FT-IR) confirmed the formation of a FeC₂O₄/nFe⁰ heterostructure, where oxalate coordinated with Fe(II) to construct a semiconductor interface that effectively inhibits anoxic passivation while enabling continuous electron supply, achieving 100% Cr(VI) removal efficiency within 20 min at an optimal oxalate/Fe molar ratio of 1/29. Mechanistic studies revealed that the oxalate ligand accelerates electron transfer from the Fe⁰ core to the surface via the FeC₂O₄-mediated pathway, as evidenced by EIS and LSV test analyses. This process dynamically regenerates surface Fe(II) active sites rather than relying on static-free Fe(II) adsorption. XPS and STEM further demonstrated that Cr(VI) was reduced to Cr(III) and uniformly co-precipitated with Fe(II/III)-oxalate complexes, effectively immobilizing chromium. The synergy between the protective semiconductor layer and the ligand-enhanced electron transfer endows nFe_oxa with superior reactivity. This work provides a ligand-engineering strategy to design robust nFe⁰-based materials for sustainable remediation of metal oxyanion-contaminated water. Full article

This study investigates the effect of nanoscale zero-valent iron (NZVI) and sediment microbial fuel cells (SMFCs) on the three typical heavy metals’ (Pb, Cr and As) removal and stabilization. Results showed that the combined use of NZVI and SMFCs obtained the highest removal efficiencies in the sediment (Pb 37.7 ± 2.2%, Cr 26.4 ± 1.5% and As 30.1 ± 2.0%) and overlying water (Pb 55.8 ± 2.3%, Cr 47.6 ± 1.9% and As 45.8 ± 2.1%). The use of an NZVI electrode can transform heavy metals with relatively weak binding into forms with stronger binding, thereby diminishing their bioavailability and toxicity. After 60 days of operation with the addition of NZVI in the SMFC system, over 50% of the Pb, Cr and As in the sediment was transformed into the residual fraction. An anodic microbial communities analysis indicated that operating a SMFC can mitigate the adverse effects of NZVI on the community diversity and increase the content of electrogenic bacteria in sediments. Consequently, our findings indicated that integrating SMFCs and NZVI represents a viable approach for remediating rivers contaminated with heavy-metal-polluted sediments. Full article

To increase the interaction between a catalyst and large pollutant molecules in industrial wastewater, this study employed worm-like micelles created by surfactants as soft templates for synthesizing structured hydrotalcites with high specific surface areas and diverse pore sizes. Following this, the integration of these hydrotalcites with AgBr yielded supported, structured hydrotalcites that exhibited enhanced redox properties. Characterization techniques, including XRD, FT-IR, SEM, and EDS, validated the successful incorporation of AgBr into the structured hydrotalcites. Furthermore, UV–Vis DRS and electrochemical analyses revealed that the integration with AgBr narrowed the band gap of the hydrotalcites, thereby expanding their light absorption range. At 25 °C with an initial solution pH of 5 and an adsorbent dosage of 0.5 g/L, the efficiency of methyl orange removal by the composite material reached 97.69% after 60 min of dark adsorption. EPR and reactive species-trapping experiments revealed that the high-efficiency degradation of methyl orange was primarily attributed to the combined action of highly active h⁺, •O₂₋, and ¹O₂ species. Full article