When words like micro- and nanoparticles are used, most think of pollutants themselves, not remediation. But sometimes, scaling down can be the way to solve the most complex issues in the environment.
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Nanotechnology for Water Treatment
The treatment of wastewater and removal of water pollutants is a huge aspect of keeping the constant supply of water clean.
Human activity and industrial processes, such as agricultural, nuclear, or textile, and contamination from domestic and factory waste, severely degrade water bodies.
Nanotechnology is an emerging solution. It offers a diverse selection of innovative routes for removing water pollutants. In fact, owing in part to the varied wastewater nanotechnological treatments, such as membrane-based filtration, nano-adsorbents, and nano-catalytic treatment processes, the wastewater treatment industry reached an estimated value of 80 billion U.S. Dollars in 2020, which continues to grow steadily at an expansion rate of around 6.5 %.2
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Sustainable Synthesis of Iron Oxide Nanoparticles for Wastewater Treatment
Experts have been focusing on the sustainable and eco-friendly development of nanoparticles (NPs) and processes for the treatment of water bodies. Specifically, green nanomaterials, such as iron-based NPs, are being recognised for their exceptional physicochemical attributes, biocompatibility, degradability, lower cost, and reduced environmental footprint.
A recent study focused on the green and eco-friendly synthesis of magnetite and hematite iron oxide NPs using Leptolyngbya foveolarum and Azospirillum brasilense for wastewater treatment.
The iron NP synthesis involved mixing L. foveolarum and A. brasilense supernatant with 100 mM FeCl3·6H2O, followed by incubation at 50 °C for one hour. The testing involved analyzing the efficiency of various Fe NP concentrations (0.25, 0.50, and 1.0 mg/mL) against 100 mL of wastewater.
Mixing both types of NPs at 1mg/mL resulted in removal efficiencies of 81.75 %, 82 %, 87.68 %, 91.87 %, and 71.9 % for COD, BOD, nitrate, phosphate, and ammonia pollutants, respectively. The testing process was constantly analyzed for 16 days, during which a consistent reduction in pollutant concentration was observed.3
The research demonstrates the success and highly efficient potential of Fe3O4 and Fe2O3 NPs in wastewater treatment.
Nanotechnological Soil Remediation: A Key Approach for Sustainable Agricultural Development
Soil pollution and contamination are another serious issue in the environment. Not only affecting crop production and human health, soil contamination can also disrupt food security and supply.
Major pollutants include organic chemicals like total petroleum hydrocarbons (TPH), pesticides, and microplastics, while inorganic pollutants include heavy metals like copper, lead, zinc, mercury, and more.
Nanoremediation could be key to reducing the bioavailability and mobility of pollutants, and aid in the conversion of harmful chemicals into harmless by-products.4
Nanomaterials as Adsorbents
Nanomaterial-based adsorbents have proven to be key in pollutant removal. Nano-adsorbents can interact with the contaminants by pore-filling process, electrostatic interaction, ionic exchange, or precipitation, leading to the removal of harmful chemicals.
Nano-biochar and biochar-based nanomaterials continue to be explored extensively for their use as adsorbents.
A popular choice is nano-zerovalent iron (nZVI)-doped biochar, which has been proven to be successful in 87 %, 82 %, and 90 % removal of cadmium, lead, and 2,4-dichlorophenol (2,4-DCP), respectively.5
Nano-catalysts for Removing Soil Pollutants
Nanomaterial-based catalysts have also become popular for the degradation of organic and inorganic contaminants by Advanced Oxidation Processes (AOPs).
One study revealed the success of biochar-supported Ni/Fe bimetallic NPs in the removal of complex pollutants like decabromodiphenyl ether, showing an efficiency of approximately 89 %.
Such sustainable nanocatalysts are becoming increasingly popular for efficient remediation without releasing any harmful byproducts.
Nanophytoremediation: Efficient Use of Nanotechnology for Ecological Sustainability
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Traditional phytoremediation involves the use of plants as a cost-effective and harmless way for removing critical pollutants from soil and water bodies. The natural ability of plants to absorb pollutants, degrade them into harmless products, and stabilize the ecosystem makes them a superior candidate for the remediation of soil, water, and air.
However, traditional phytoremediation techniques are an extremely slow process, and cannot match the rising pollutant levels in ecological systems. Nanotechnology, or more specifically, nanoparticles, could be the solution.
If integrated successfully, their higher surface area-to-volume ratio can increase reactivity and degradation in a wide variety of contaminants.
Advantages of Using NPs for Phytoremediation Processes
The use of specialized NPs can enhance detection, removal, and degradation during remediation. Nanoparticles such as nano-zerovalent iron and fullerene have been key in boosting the bioavailability of pollutants and increasing plant adsorption rates.
Metal oxide TiO2 nanoparticles, among others, can break down complex organic contaminants into simple and easily adsorbable products, facilitating the uptake of remediation plants.
The use of nanotechnology has also been pivotal in boosting the growth rate of plants and improving their stress tolerance. The antioxidant enzyme activity accelerates in the presence of NPs, protecting plants from oxidative damage from heavy metals.
During phytoremediation, nanoparticles immobilize metal particles in the soil, reducing soil toxicity and enabling plants to build tolerance to and remove contaminants.
Nanoparticles such as Zinc oxide (ZnO) have been useful in degrading harmful pollutants. These NPs in the presence of sunlight act as photocatalysts, enhancing the oxidative reactions leading to the degradation of organic dyes and pesticides.
Similarly, carbon-based NPs such as carbon nanotubes (CNTs) and graphene oxide (GO) have been shown to act as enzyme carriers, significantly boosting the degradation of organic chemicals.6
Despite nanotechnology's observed enhancements to phytoremediation, selecting the appropriate NP based on plant species, ecological conditions, and pollutant types is a highly complex task.
On top of this, NPs can react with beneficial microorganisms in the soil, destroying their microbial communities and severely affecting both soil fertility and stability of the ecosystem.
The long-term effects of NPs accumulating in food chains are also unknown and need to be better understood before such techniques can become widespread. Initial studies, for instance, have found nanoparticles can cause ecotoxicological effects like DNA damage, growth inhibition, and oxidative stress.6,7
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Risks and Challenges Associated with the Use of Nanotechnology for Environmental Remediation
There are certain risks and regulatory hurdles involved in scaling nanotechnological processes for ecological preservation.
The production of nanomaterials used for wastewater treatment is usually highly complex and energy-intensive. This poses serious concerns about the sustainability and efficiency of the nanotechnological process.
For air filtration, CNT-based filters are being researched and integrated into advanced filtration systems to capture and degrade particulate matter, aerosols, and microbes. However, experimental studies have shown that inhaling CNTs can lead to lung inflammation and fibrosis in rats, with long-term exposure posing serious concerns about lung cancers.
All of these issues remain unresolved due to the absence of any standardized risk assessment procedure for NPs. A standardized framework for ecological risk assessment of nanomaterials will be the first step toward addressing toxicity issues.7
When dealing with soil contamination, the use of nanocarriers has been highly beneficial, but accurately monitoring and controlling delivery behavior through soil irrigation or foliar spray to enable appropriate dosage at the required time and place remains highly challenging.
Most promising soil remediation technologies involving the use of nanotechnology are still in the research phase, with increasing them to the industrial scale without any compromise to their functionality a major hurdle.8
Despite these significant challenges, the use of modern technologies like Machine Learning (ML) may prove to be key in the production of highly optimized and functional nanomaterials. ML tools are being trained for semi-quantification of particle size and number and automated image analysis for classification, which will be beneficial for developing an environmental risk assessment (ERA) framework.
The integration of risk assessment frameworks and ML tools into life cycle analysis (LCA) and the sustainable development of nanotechnology will bring us into a new phase of ecological preservation and pollutant degradation.
Further Reading
- Tariq, N. et. al. (2025). Nanotechnology in Environmental Remediation: A Sustainable Frontier. Journal of Medical & Health Sciences Review, 2(2). Available at: https://doi.org/10.62019/rjsvwh72
- Pandit, S. et. al. (2025). Life cycle assessment and techno-economic analysis of nanotechnology-based wastewater treatment: Status, challenges and future prospectives. Journal of the Taiwan Institute of Chemical Engineers. 105567. 166 (2). Available at: https://doi.org/10.1016/j.jtice.2024.105567
- Sheekh, M. et. al. (2025). Green synthesis of iron oxide nanoparticles using Lyptolyngbya foveolarum and Azospirillum brasilense for wastewater treatment. Int. J. Environ. Sci. Technol. 22, 9933–9948. Available at: https://doi.org/10.1007/s13762-024-06257-5
- Li, Y. et. al. (2022). Remediation of soil contaminated with organic compounds by nanoscale zero-valent iron: A review. Science of The Total Environment. 143413. 760. Available at: https://doi.org/10.1016/j.scitotenv.2020.143413
- Qian, W. et. al. (2022). A porous biochar supported nanoscale zero-valent iron material highly efficient for the simultaneous remediation of cadmium and lead contaminated soil. Journal of Environmental Sciences. 113. 231-242. Available at: https://doi.org/10.1016/j.jes.2021.06.014
- Gomes, M.P. (2025). Nanophytoremediation: advancing phytoremediation efficiency through nanotechnology integration. Discov. Plants 2, 8. Available at: https://doi.org/10.1007/s44372-025-00090-x
- Rajabzadeh, H. et. al. (2025). Nanotechnology in Environmental Remediation: Opportunities and Risks. International Journal of New Chemistry. 11(4). 776-791. ISSN: 2645-7237. Available at: https://www.doi.org/10.22034/ijnc.2025.721221
- Elsayed, M. et. al. (2025). Nanotechnology-enabled soil management for sustainable agriculture: interactions, challenges, and prospects. Environ. Sci. Nano. 12. 2128 - 2153. Available at: https://doi.org/10.1039/D4EN00943F
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