Carbon-based nanocomposite materials with multifunctional attributes for environmental remediation of emerging pollutants

Cutting-edge nanotechnology approaches for efficient mercury remediation: Mechanisms, innovations and future prospects in polluted environments

Mercury contamination poses a significant threat to the environment and human health due to its persistence, bioaccumulation, and toxicity. Conventional remediation methods such as chemical precipitation, coagulation, and membrane filtration often fall short due to limitations like incomplete removal, secondary pollution, and low selectivity. In response, advanced nanomaterials, defined as engineered nanostructures with high surface area, tunable surface chemistry, and exceptional mercury-binding capabilities, have emerged as powerful alternatives. This review critically evaluates five major classes of nanomaterials, such as carbon-based nanomaterials, metal and metal oxide nanoparticles, functionalized polymer nanocomposites, biosynthesized nanoparticles, and hybrid nanomaterials, with a focus on their mercury removal efficiency, regeneration capacity, environmental safety, and real-world applicability. While these materials have been previously reported, this work offers a unique comparative analysis that synthesizes fragmented data across the literature to highlight performance trade-offs and implementation feasibility. Furthermore, nanotechnology-assisted techniques including adsorption, photocatalysis, membrane-based separation, and hybrid treatment systems are systematically reviewed, emphasizing removal efficiencies, operational parameters, and scalability. Among these, hybrid nanomaterials and multifunctional systems demonstrate the highest potential, achieving mercury removal rates exceeding 95 % and offering adaptability to complex contaminated matrices. Rather than introducing new experimental data, this review identifies key research gaps, unresolved challenges such as nanoparticle toxicity and recovery, and the lack of field-scale validation. It concludes with a roadmap to guide future research toward the development of safe, cost-effective, and environmentally sustainable nanotechnology-driven mercury remediation strategies. This work aims to support informed decision-making among researchers, engineers, and environmental policymakers working to mitigate mercury pollution effectively.

Selective recovery of europium from real acid mine drainage using modified Cr-MIL and SBA15 adsorbents

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal-organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost-benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD.

Recyclable Multifunctional Nanocomposites Based on Carbon Nanotube Reinforced Vitrimers with Shape Memory and Joule Heating Capabilities

The present study focuses on the multifunctional capabilities of carbon nanotube (CNT)-reinforced vitrimers. More specifically, the thermomechanical properties, the Joule effect heating capabilities, the electrical conductivity, the shape memory, and the chemical recycling capacity are explored as a function of the CNT content and the NH2/epoxy ratio. It is observed that the electrical conductivity increases with the CNT content due to a higher number of electrical pathways, while the effect of the NH2/epoxy ratio is not as prevalent. Moreover, the Tg of the material decreases when increasing the NH2/epoxy ratio due to the lower cross-link density, whereas the effect of the CNTs is more complex, in some cases promoting a steric hindrance. The results of Joule heating tests prove the suitability of the proposed materials for resistive heating, reaching average temperatures above 200 °C when applying 100 V for the most electrically conductive samples. Shape memory behavior shows an outstanding shape fixity ratio in every case (around 100%) and a higher shape recovery ratio (95% for the best-tested condition) when decreasing the NH2/epoxy ratio and increasing the CNT content, as both hinder the rearrangement of the dynamic bonds. Finally, the results of the recyclability tests show the ability to regain the nanoreinforcement for their further use. Therefore, from a multifunctional analysis, it can be stated that the proposed materials present promising properties for a wide range of applications, such as Anti-icing and De-icing Systems (ADIS), Joule heating devices for comfort or thermotherapy, or self-deployable structures, among others.

Functionalized gum acacia-activated carbon-CaO/NiO nanocomposite for potential photocatalytic removal of organic pollutants from water

A functionalized gum acacia-activated carbon-CaO/NiO nanocomposite was synthesized using an eco-friendly sol-gel method. The formed nanocomposite was designed to apply various light sources to enhance the improved removal of organic dyes such as methylene blue, methyl orange, methyl red, and rhodamine B from aqueous media. The band gap energies of CaO, NiO nanoparticles and gum acacia-activated carbon were 3.54, 4.28, and 5.34 eV, respectively, corresponding to a reflection edge of 350, 290, and 232 nm, respectively. The surface area of the synthesized nanocomposite was measured to be 17.892 m2 g-1. Sunlight and 20 mg L-1 of the nanocomposite quenched the dyes (methylene blue, 99.7%; methyl orange, 98.3%; methyl red, 96.7%; and rhodamine B, 93.5%) after 120, 100, 100, and 75 min of irradiation, respectively. However, after 80, 100, 100, and 75 min, the percentage of dyes under UV light irradiation was 98.6%, 95.8%, 98.4%, and 94.2% for methylene blue, methyl orange, methyl red, and rhodamine B, respectively. The nanocomposite showed excellent stability after five cycles of dye reduction.

Hydrogels from a Self-Assembling Tripeptide and Carbon Nanotubes (CNTs): Comparison between Single-Walled and Double-Walled CNTs

Supramolecular hydrogels obtained from the self-organization of simple peptides, such as tripeptides, are attractive soft materials. Their viscoelastic properties can be enhanced through the inclusion of carbon nanomaterials (CNMs), although their presence can also hinder self-assembly, thus requiring investigation of the compatibility of CNMs with peptide supramolecular organization. In this work, we compared single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) as nanostructured additives for a tripeptide hydrogel, revealing superior performance by the latter. Several spectroscopic techniques, as well as thermogravimetric analyses, microscopy, and rheology data, provide details to elucidate the structure and behavior of nanocomposite hydrogels of this kind.

Recent advances in carbon-based nanomaterials for the treatment of toxic inorganic pollutants in wastewater

Wastewater contains inorganic pollutants, generated by industrial and domestic sources, such as heavy metals, antibiotics, and chemical pesticides, and these pollutants cause many environmental problems.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H2O2 neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Nanohybrid catalysts with porous structures for environmental remediation through photocatalytic degradation of emerging pollutants

Water supplies have been seriously challenged by new emerging pollutants, which are difficult to remove by traditional wastewater treatment. Thus, new technologies such as catalytic advanced oxidation processes have merged as suitable solutions; however, the drawbacks of typical catalysts limit their application. To overcome this issue, new materials with enhanced textural properties have been developed, showing that their porosity and chemical nature influence their potential as a catalyst. Herein, the recent progress in highly porous catalysts and their suitable deployment to effectively nano-remediate the polluted environmental matrices are reviewed in detail. First, following a brief introduction, several environmental pollutants of emerging concerns from different sectors, including pharmaceutical residues, endocrine-disrupting chemicals (EDCs), pesticides, and hazardous dyes are also introduced with relevant examples. To effectively tackle the sustainable remediation of emerging pollutants, this work also focuses on the multifunctional features of nanohybrid porous materials that act as catalysts constructs to degrade emerging pollutants. The influence of surface reactive centers, stability, bandgap energies, light absorption capacities, and pollutants adsorption capacities are also discussed. Successful examples of the employment of nanohybrid porous catalysts for the degradation of pharmaceutical pollutants, EDCs, pesticides, and hazardous dyes are summarized. Finally, some challenges faced by nanohybrid porous materials to achieve their potential application as advanced catalysts for environmental remediation have been identified and presented herein.