Accessing safe water sources is a global issue outlined by the Intergovernmental Panel on Climate Change (IPCC)’s 2021 report. In this document, the impact of climate change on water availability and quality, as well as food production and biodiversity, is made clear. The influence of human activities and the increase in environmental degradation has affected the availability of clean and transportable water, a primary environmental concern. Approximately 2.6 million people live in unhygienic conditions and are at risk of higher mortality rates due to the consumption of hazardous water.
Water scarcity is predicted to worsen. Recurrences of drought increased population size, and urbanization is agreed to have had contributed to the current state of global water resources. However, novel nanotechnology research utilizing polymeric electrospun nanofibrous membranes for water treatment could be a promising solution. This article will provide an overview of this nanotechnology, exploring how it may assist in solving a critical concern outlined by the IPCC’s reports.
The Depletion in Vital Natural Resources
The rise in environmentally harmful human activity has led to an associated increase in the depletion of natural energy resources and pollution. Additionally, with an expanding population, the demand for freshwater resources has been enhanced. From 2000 to 2016, a 5 % growth in urban populations was observed. As this rate is unlikely to stop anytime soon, countries have been increasing their chemical, pharmaceutical, and automotive outputs to meet increasing population demands. Water resources are in rapid decline as a result.
According to the IPCC, carbon emission mitigation by developed countries has not driven the survival of the Earth; the lack of development within less economically countries is to thank. The balance provided by these underdeveloped countries that do not produce the same level of carbon emission and pollution has been an unexpected benefit. However, with the demand for resources and rise in unsustainable waste, developed countries are also affected by depleting water resources.
Advancements in the nanotechnology sector have meant hope for replenishing water sources exists, as novel research has highlighted the potential of electrospun nanofiber membranes as a water filtration method.
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Electrospun Nanofiber Membranes
Nanotechnology and nanomaterials are defined by having a diameter of 100 nm or less. Their benefits are widespread, ranging from medicine to environmental applications. Nanofibers have a high surface-to-volume ratio, as well as high porosity, mechanical robustness, and more. Electrospun nanofiber membranes (ENMs) can play a significant role in water treatment due to their beneficial characteristics, providing a promising future for long-lasting, safe water availability.
The utilization of nanomembranes has been researched for the purposes of water purification through nanofiltration, reverse osmosis, microfiltration, and ultrafiltration. This is due to conventional water treatments such as flocculation or coagulation being unable to remove carbon and other organic pollutants from water; extra ‘sludge’ can also be produced, requiring further treatment and disposal.
Novel filtration using electrospun nanoporous membranes could be a promising method for advanced water treatments. This lightweight method is cost-effective, having a lower energy consumption compared to traditional chlorine technology.
Fabrication of polymeric nanofibers consists of many processing techniques. Electrospinning, for example, involves the application of a high-voltage electrical field between the polymer solution and the collector, separated by a distance.
The electrical force overcomes any surface tension of the polymer solution, ultimately resulting in the ejection of a thin jet. This charged jet then undergoes a series of motions, stretching and bending due to solvent evaporation and charge repulsion, resulting in solid fibers in the collector. Essentially, this method is based upon producing micro and nano-sized fibers through electrostatic repulsive forces from a solution or melt.
Electrospinning of nanofibers at Ghent University for various novel applications.
Video Credit: Ghent University - Textile Science and Engineering/YouTube.com
Benefits of Electrospun Nanofiber Membranes
Wastewater can contain many hazardous pathogens, bacteria, viruses, fungi as well as chemical pollutants. Eliminating contaminants would be beneficial for both underdeveloped countries where water-borne viruses are found, and developed countries with high chemical waste.
The use of ENMs can effectively remove and filter hazardous waste from unsafe water, eliminating total dissolved solids as well as the potential to remove protozoa and bacteria like E.Coli.
Polymeric electrospun nanofibrous membranes are more eco-friendly than membranes created through conventional phase inversion techniques, which can have low permeance, uneven pore size, and lack mechanical strength. Furthermore, ENM polymers can be recyclable and reusable, making them more sustainable than non-degradable polymer-based phased inversion membranes.
First identified in 1930, this technique has a low cost of exploitation, a short processing time, and the ability to be functionalized through additives such as nanoparticle catalysts or drugs.
Current Challenges of ENM
Using such advanced nanotechnology for water filtration and treatment would be critical for addressing the global water shortage. However, there are obstacles that require overcoming before this research can be utilized as a mainstream water treatment method.
The challenges of using nanotechnology-based electrospun nanofiber membranes consist of their lack of readiness for large-scale commercialization. While this technology can be found available on the market, it is limited due to its novelty, and other ENM filtration technology is still in its developmental stage. Technical challenges are also a hindrance, such as compatibility with already existing infrastructures, health risks, and cost of operation.
While these obstacles would require cost-benefit discussions from governmental and research institutions before being propagated within industries and commercial markets, the environmental benefit with its implementation is promising. Considering the IPCC’s goal to reduce anthropogenic impacts on already limited water sources, the use of ENMs could revolutionize the treatment of wastewater and provide a long-lasting global solution.
Industrial Response to Climate Change
This article is a part of the IPCC Editorial Series: Industrial Response to Climate Change, a collection of content exploring how different sectors are responding to issues highlighted within the IPCC 2018 and 2021 reports. Here, Nano showcases the research institutions, industrial organizations, and innovative technologies driving adaptive solutions to mitigate climate change.
References and Further Reading
IPCC. (2018) Summary for Policymakers. Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Available at: https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_SPM_version_report_LR.pdf
IPCC. (2021) Summary for Policymakers. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate. Available at: https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf
Nagar, A. and Pradeep, T., (2020) Clean Water through Nanotechnology: Needs, Gaps, and Fulfillment. ACS Nano, 14(6), pp.6420-6435. Available at: https://doi.org/10.1021/acsnano.9b01730
Tlili, I. and Alkanhal, T., (2019) Nanotechnology for water purification: electrospun nanofibrous membrane in water and wastewater treatment. Journal of Water Reuse and Desalination, 9(3), pp.232-248. Available at: https://doi.org/10.2166/wrd.2019.057
T. M., S., Arshad, A., Lin, P., Widakdo, J., H. K., M., Austria, H., Hu, C., Lai, J. and Hung, W., (2021) A review of recent progress in polymeric electrospun nanofiber membranes in addressing safe water global issues. RSC Advances, 11(16), pp.9638-9663. Available at: https://doi.org/10.1039/D1RA00060H
Wang, X. and Hsiao, B., (2016) Electrospun nanofiber membranes. Current Opinion in Chemical Engineering, 12, pp.62-81. Available at: https://doi.org/10.1016/j.coche.2016.03.001