The world is facing significant environmental challenges such as improving the quality of air, soil, and water. Currently, industry is focusing on detecting pollutants (from chemical spills, fertilizer and pesticide run-off), improving industrial and mining sites, treating contaminants and stopping further pollution.
A potential solution to these problems is to use nanomaterials. Nanomaterials can be used to assist with cleaning the environment and even provide efficient energy solutions, such as nanomaterial based solar cells. In addition to this, nanomaterials help to improve the quality and performance of many consumer products. As a result of this, the exposure to manufactured nanomaterials is increasing day-by-day. However, there are both positive and negative impacts on the environment due to nanotechnology.
With the help of nanotechnology, water quality can be improved. Some of the nanomaterials that can be used for remediation of water are carbon nanotubes (CNTs), zeolites, nanoparticles of zero valent iron (ZVI), silver nanoparticles, etc. Other nanomaterials like zinc oxide (ZnO), titanium dioxide (TiO2), tungsten oxide, serve as a photocatalyst. These photocatalysts can oxidize organic pollutants into harmless materials. TiO2 is the most preferred material as it has high photostability, high photoconductivity, easily available, inexpensive and non-toxic. Silver nanoparticles have antimicrobial effect. Also, many polymeric nanoparticles are being used for wastewater treatment.
Another new technology is known as nanofiltration which can be used in water treatment in homes, offices, and industries. Molybdenum disulphide (MoS2) nonporous membrane is used for energy efficient desalination of water which filters five times more than the conventional ones. To clean oil spills in the water bodies, a nanofabric paper towel has been developed which are woven from tiny wires of potassium manganese oxide that can absorb oil 20 times its weight. Thus, nanotechnology provides a solution to clean the contaminated water and prevent new pollution.
With the help of nanotechnology, toxic gases in the air can be cleaned. But first, we have to detect the pollutants at the molecular level using precise sensors. A sensor called nanocontact sensor has been developed which can detect the heavy metal ions and radioactive elements. These sensors have a small size, are inexpensive and are easy to use on-site. Currently, single-walled nanotubes (SWNTs) are being used for the detection of NO2 and NH3 gases. Also, SWNTs sensor can accomplish high sensing activity at room temperature when compared to the conventional sensors which work at 200 to 600◦C. Cantilever sensors have been developed to sense VOCs, heavy metals and pesticides. A mixture of CNTs with gold particles helps adsorb toxic gases like NOx, SO2 and CO2. Another porous nanomaterial manganese oxide has better adsorption of toxic gases due to its large surface area.
Therefore, by detecting pollutants by specific sensors, we can help protect the sustainability of human health and the environment. Thus, nanotechnology provides us with a new approach to cut down the waste production, reduce the emission of greenhouse gases and discharge of hazardous chemicals in water bodies.
Nanomaterials can also have a negative impact. Currently there is very little information describing the relative environmental risk of the manufactured nanomaterials. Only a few studies have been conducted with the aim of discovering the direct and indirect exposure to nanomaterials and there are no clear guidelines to quantify the effects.
Recently, a workshop, conducted by the National Science Foundation and the US Environmental Protection Agency, was undertaken to identify the critical risk issues concerning nanomaterials. Specifically, the workshop aimed at determining the exposure and toxicity of manufactured nanoparticles, ability to extrapolate manufactured nanoparticles toxicity using existing particle and fiber toxicology database, and recyclability and overall sustainability of the manufactured nanomaterials.
A remedial solution is the use of green technology or green manufacturing. This is an environmentally friendly technology which is developed and used to conserve natural resources. This technology aims at producing nanomaterials with lesser raw materials, minimum energy consumption, and minimum waste production. It is known that any manufacturing process is accompanied by a large amount of waste production. This is minimized by green manufacturing, which uses green chemicals which are less harmful to the environment and energy efficient processes. Microemulsions, which are used instead of VOCs in the cleaning industry, are an example of green technology.
Thus, scientific authorities are monitoring various nanoparticles produced and used, as well as their subsequent impact. This is in order to balance the technology’s benefits and possible unintended consequences.