The Important Role of Nanotechnology in the Future of Water Filtration
By: Yvonne Rose Passaro
Tags: Water, Nanotechnology, Future

Water is synonymous with life; all living things require it to live. According to data from the World Health Organization in 2019, 1 in 3 people globally do not have access to safe drinking water. With the U.N. explicitly recognizing the human right to water and sanitation, stricter public policies should be put into place holding large corporations responsible for the materials they produce along with their ecological affect.

In both developing and industrialized countries, a growing number of micro-pollutants are entering bodies of water at rapid rates. Current methods of water purification include reverse osmosis and micro-filtration, yet they require copious amounts of energy to run. Carbon nanotubes, a popular type of nano-material, have cylindrical molecules made up of a single layer of carbon atoms joined together like miniature lattices that can filter many things, including water. CNT’s have contributed to the development of more efficient treatment processes as many current membranes and filtration systems are based on them. However, according to an article in 2015 from US National Library of Medicine National Institutes of Health, “their use on an industrial scale for large municipal water and wastewater treatment plants is not expected in the midterm because of high production costs”.

Researchers have also explored the use of magnetic nanoparticles in binding with contaminants. Having such large surface areas relative to their volume, these magnetic nanoparticles readily bind with water-borne contaminants such as arsenic or oil. A new water purification method based on magnetic nanoparticles coated with an ‘’ionic liquid’’ simultaneously removes organic, inorganic, and microbial contaminants, as well as micro-plastics. The nanoparticles are then easily removed with magnets.

In laboratory tests, these nanoparticles reliably removed lead, nickel, copper, chromium, and cobalt ions, as well as a dye that was used to model organic impurities. It is also noted that the growth of various bacteria was effectively halted. In addition, the nanoparticles attached themselves to the surface of polystyrene spheres which were used as a model for the filtration of micro-plastics. The further research and optimization of these components could lead to the effective purification of large amounts of water without extensive infrastructure and cost.

The use of nanosilver has also been implemented in many filtration systems today. Silver has been known to have antibacterial properties since Roman times. However, an article from AZO NANO argues:

“Nanotechnology is a highly effective alternative method to removing a wide range of contaminants from any type of water supply. Despite their high specificity in eliminating certain contaminants, nanomaterials exhibit certain limitations, especially when considering the potential uptake of these materials into wildlife. For example TiO2 and silver nanoparticles, some of the most commonly used nanoparticle species, can have particularly harmful effects on aquatic organisms including bacteria, algae, invertebrates, fish and plants. To combat the potential adverse effects associated with the use of certain nano-water filtration systems, it is imperative that both national and international efforts are made to develop highly efficient systems capable of monitoring the levels of nanoengineered materials within our water supplies.”

The article highlights the importance of proper research and regulation when it comes to exploring the effectivity of nano-materials. It is also important to note the method in which these materials are produced also greatly affects their quality. For example, Chemical Vapor Deposition is an enticingly cost-effective method for big business as it allows the capacity to manufacture on a large scale which equates to a greater profit. However, from a macro perspective, CVD is not the most effective nor accurate way in which we as a species can implement such technologies. Notable defects do occur with CVD and the effects on the consumer — and our environment — are not researched and still remain fully unknown.

In another article published by the Nacional Center for Biotechnology Institute entitled,“The Toxic Truth About Carbon Nanotubes in Water Purification: a Perspective View” it asserts,

“Although scientific efforts to design risk estimates are evolving, there remains a paucity of knowledge on the unknown health risks of CNTs. The absence of universal CNT safety guidelines is a specific hindrance…We propose a CNT safety clock that will help assess risk appraisal and management. We suggest that this could form the basis of an acceptable CNT safety guideline. We pay particular emphasis on measuring risks based on CNT physico-chemical properties such as diameter, length, aspect ratio, type, charge, hydrophobicity, functionalities and so on which determine CNT behaviour in waste water treatment plants and subsequent release into the environment.”

These proposals are important to consider as proper implementation of safety guidelines will serve as the pillars upholding the integrity and instrinsic value of this emerging technology. The effectiveness of nanotechnology when it comes to different types of contaminants is also important to discuss. In the Journal of Water Reuse and Desalination, it states:

“Nanofiltration has very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia). Similarly, nanofiltration can remove bacteria (for example, Campylobacter, Salmonella, Shigella) effectively. Nanofiltration can also remove viruses (for example, enteric viruses, hepatitis A, norovirus, and rotavirus) effectively. However, nano-filtration has moderate effectiveness in removing chemicals.”

This raises the question of how we can best utilize nanotechnology to effectively filter out compounding chemical contaminants — from pesticides to pharmaceutical drugs — that are also greatly affecting our drinking water. As nanotechnology will continue to be infused into various aspects of society’s infrastructure, it is important to explore the subject from all angles. Could we use pipes lined with nanomaterials to filter water on the way to our faucet? What could the negative implications be of this? What about using the nanoscale manipulation of light? Nanotechnology holds the potential to provide humanity with long-term solutions in maintaining the value of our planets many important resources, especially water. With sagacity and discernment, we can use it to help improve the quality of life for us all.