Water Purification

What is a Water 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 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 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 nitrates and wastewater recycling in laundries [5].

Figure 2: Nanofiltration Membrane Purification Capability [5]