Table of Contents
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| Figure 1: Different Methods of Water Purification [1] |
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What is
aWater Purification?
Water purification is any process that removes contaminants that exist within water, in order to make it more fit for various uses. In the coming years, it is expected that water scarcities will increase as a result of droughts, population growth, and urbanization [2]. Figure 1 demonstrates the progress that has already been made with various water purification methods, from boiling and sedimentation to the use of ultraviolet light and reverse osmosis. Nanotechnology is an area that has the potential to provide new approaches to water purification while also reducing chemical usage and favoring the environment.
Nanoparticles for Water Purification
Nanoparticles have been an interest in the topic of water purification for their ability to disperse well in water, along with their photothermal photo-thermal properties, converting light to heat, and photocatalytic properties, using light to activate a chemical process [3]. One problem however, is the poor stability of nanoparticles as since stabilizing agents are typically not suitable for water purification methods.
Janus Gold Nanorods
The Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment has designed a gold nanorods that are half-coated with silica. This coating technique solves the stability obstacle, while also allowing the nanorods to disperse well and stay separated in water. The nanorods absorb light and produce localized heat capable of destroying pollutants present within the water [3].
Nanofiltration
Nanofiltration uses nanofilters with a pore size of around 0.01 nanometers, capable of removing suspended solids as well as bacteria, viruses, and nearly all multivalent ions [4]. Since nanofiltration has the ability to remove multivalent ions from water, it is often used as a water softening method. Additionally, depending on the application, this process is followed by reverse osmosis, which has an even smaller pore size and is capable of removing monovalent ions as well. Some additional applications of nanofiltration include ; removing pesticides from groundwater, removing heavy metals from wastewater, removal of removing nitrates from water, and wastewater recycling in laundries laundry [5].
| Figure 2: Nanofiltration Membrane Purification Capability [5] |
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Carbon Nanotube Filters
Carbon Nanotubes nanotubes (CNTs) have been recognized for their potential to remove salts and minerals from water due to their strong selectivity to remove pollutants and frictionless movement through water. CNTs with hydrophilic, positive and negative functional groups attract water to the opening of the tube, while the CNT itself is hydrophobic. Once water enters the CNT through the opening, it is repelled by the walls of the tube and the water moves quickly through the filter. Electrostatic attractions between the water salts and CNT functional groups allow only the pure water to pass through the CNT filters [6].
| Figure 3: Carbon Nanotube Water Filtration Process |
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[1] Bestwaterpurifiers_l8ai7r. (2020, July 05). Bestwaterpurifiers. Retrieved April 12, 2021, from https://bestwaterpurifiers.co.in/
[2] Tlili, I., & Alkanhal, T. (2019, September 01). Nanotechnology for water purification: Electrospun nanofibrous membrane in water and wastewater treatment. Retrieved April 12, 2021, from https://iwaponline.com/jwrd/article/9/3/232/65579/Nanotechnology-for-water-purification-electrospun
[3] Weir, W. (2020, June 22). New gold nanoparticle purifies water of difficult pollutants. Retrieved April 12, 2021, from https://news.yale.edu/2020/06/22/new-gold-nanoparticle-purifies-water-difficult-pollutants#:~:text=Researchers%20have%20found%20a%20promising,that%20converts%20light%20to%20heat.&text=Certain%20chemical%20treatment%20processes%20%E2%80%94%20typically,UV%20light%20%E2%80%94%20have%20proven%20effective.
[4] Hancock, N. (2018, August 15). Ultrafiltration, Nanofiltration and reverse osmosis. Retrieved April 12, 2021, from https://www.safewater.org/fact-sheets-1/2017/1/23/ultrafiltrationnanoandro
[5] Nano Filtration. (n.d.). Retrieved April 12, 2021, from http://www.osmotechmembranes.com/nano-filtration.php
[6] Zuo, L. (2020, April 08). Carbon nanotubes: The future of the planet's freshwater. Retrieved April 12, 2021, from https://ysjournal.com/carbon-nanotubes-the-future-of-the-planets-freshwater/
Contributors:
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Faculty Advisor: Ahmad Ghavami