Emerging Field of Nanotechnology in Environment

Abstract

The art of utilizing and manipulating micro materials have been dated back to antient era. With the advancement in technologies, the state-of-art methods of nano technologies and nano sciences has been employed in various sectors including environment, product designing, food industry, pharmaceuticals industries to way out solve standard problem of mankind. Due to rapid industrialization and the alarming levels of pollution there has been an urgent need to address the environmental and energy issues. Environmental sustainability concerns the global climate change and pollution including air, water, soil. The field of nanotechnology has proven to be a promising field where sensing and remediation, have been dramatically advanced by the use of nanomaterials. This emergent science of surface to mass ratio is the principle theorem for manipulating structure at molecular levels. The review sums up all the advancements in the field of nanotechnology and their recent application in the environment. New opportunities and challenges have also been discussed in detail to understand the use of nanotechnology as problem-to-solution ratio.

Graphical abstract

Image depicting the application of nanotechnology in environmental concerns. The combinations of technologies like bioremediations, bioaugmentations with state-of-the-art nanotechnology like carbon nanotubes and Nano capsules to answer the environmental challenges of soil quality, and plant productivity.

An Early Phase of Nanotechnology: A Background Tale

The microscopic universe of nano-sciences have opened up huge possibilities and opportunities for science and industries. This high-tech branch deploys the molecular structure of materials with the aim to change their intrinsic properties. In 1959 the American Nobel prize winner and physicist Richard Feynman was the first to introduce the idea and applications of nanotechnology in his talk ‘There’s plenty of Room at the Bottom’ at the California Institute of Technology (Caltech) [1]. Even though the term nanotechnology was not introduced but the methodology to manipulate and control atoms and molecules were discussed in detail. Later in the year 1981, the term modern nanotechnology was introduced with the discovery of manipulation of individual atoms using scanning tunnelling microscope, a microscope for which IBM scientists Gerd Binnig and Heinrich Rohrer won the 1986 Nobel Prize in Physics [2]. But the journey of using nanomaterial dated back to fourth century when gold and silver were added to glass to create startling effects [1]. Another usage of this technique was seen in the famous Lycurgus cup, which changes colour depending on the location of the light source [3]. The early research in late 1960’s enabled researchers to manipulate small objects using micro and nano tools.

With more than 20 years of research in the field of nanoscience and approximately more than fifteen years of research and development, applications of nanotechnology are delivering in both anticipated as well as unanticipated ways on its potential to aid society. Various classified discoveries from the year 1990s include carbon nanotube and by the early 2000s, nanomaterials were utilized in consumer products from sports equipment to digital cameras (Fig. 1) [4, 5]. Currently this area has been consolidated, well marketed and the nano-industry has marked its existence. It includes other areas such as micro-manufacturing, organic chemistry and molecular biology [6–10]. Nanotechnology provides numerous benefits in almost all areas of life, including many technological and industrial sectors, such as information technology, energy, medicine, national security, environmental science, food safety, and many others [11–17]. Nanotechnology is considered as an integral part of "Science, Technology, Engineering, and Mathematics (STEM) education". The types of nanotechnology are categorized into Top-down, Botton-up, Dry and wet nanotechnology based on their process of functioning and medium in which they work. Most of those tools were used to operate and target biological samples especially humans and animals to build microbiological machines with applications in diagnosis, biosensing, and bioelectronics. The development of Atomic Field Microscope (AFM), Scanning Electron Microscope(SEM), Transmission Electron Microscope (TEM) have been a path breaker in the scientific history [18]. But each technology had its shortcomings thus, with the advent of technology the state-of-art nano-technology based methods have been employed to improve the short comings. In this review we have compiled the up-to-date information over the current scientific scenario pertaining to nanotechnologies and the recent upcoming ways which are being employed to further refine these methods have been discussed (Fig. 2). With the huge amount of research carried out in this field over the past 20 years, it is now assured that more and more micro- and nanofabrication based methods will be developed in the near future as manipulation techniques for biological samples.

Fig. 1.

Detailed timeline of research and development in journey of nanotechnology starting from the development of lycurgus cup in fourth century to future scopes in the field on Nanooptics, Nanophotonics and Nanobots

Fig. 2.

The figure sums up various sectors and fields including medicine, environment, food that have utilized the science of nanotechnology for problem solving

Current Usage of Nano-techniques in Environment

Governments around the world are making regulatory changes to support the adoption of nanotechnology in agriculture, with the aim of boosting production and improving food supply systems. Nanotechnology offers unique advantages in this field, including the use of nanochemicals such as nanopesticides, nanoherbicides, and nanofertilizers, as well as specialized technologies such as precision farming methods and intelligent feed. These approaches can improve crop production, enhance the quality and texture of food, increase bioavailability and nutrient values, and improve packaging and labeling practices, among other benefits. Overall, nanotechnology is transforming the entire process of food production, from the field to the table. [19–21]. Additionally, the use of phosphatic nanofertilizers has been associated with an increase in soybean growth rate (by 32%) and seed yield (by 20%) [22]. Numerous contaminants, such as chlorinated chemicals, hydrocarbons, organic compounds, and heavy metals, have been remedied in recent years using nanoscale zero valent iron (nZVI), carbon nanotubes, and nano-fibers [23]. Nanotechnology has recently impacted a wide range of scientific and technological fields, including engineering, medicine, pharmaceuticals, agriculture, the environment, and many more [24, 25]. The successful use of nanoparticles (NMs), such as titanium dioxide and zinc oxide, in the production of cosmetics, sunscreens, surface coatings, and various food products is one of the many general uses of nanotechnology. A growing number of products, including food packaging, clothes, household cleaners, bandages, and water purification systems, contain silver nanoparticles. Further proof of the economic significance of nanotechnology is provided by the usage of carbon nanotubes in solar panels [26, 27]. Leachate from a municipal solid waste landfill was reported to have had a significant impact on nearby shallow aquifers of basalt, where groundwater physio-chemical characteristics showed elevated levels of heavy metals such Al, Cd, Cr, Fe, Zn, Ni, and Pb [28–33]. Reactive oxygen species were produced in living cells as a result of the oxidation of the nZVI in Escherichia coli, Pseudomonas fluorescens, and Bacillus subtilis var. niger, which are pure cultures of bacteria [34]. Due to its antibacterial properties, silver NP is the one used most frequently in industry, while gold NP is extensively researched as a sensor/detector [35–42]. Nanosensors are analytical tools designed to measure physico-chemical properties in hard-to-reach areas and have at least one sensing dimension smaller than 100 nm. In biology and chemistry, it is common practice to use nanowires, nanotubes, nanoparticles, or nanocrystals to improve the signal transduction generated by sensing elements in response to exposure to analytes of comparable size. They can be employed in multiplexed systems and have special surface chemistry, specific thermal, electrical, and optical properties that help to improve sensitivity, speed up response, and increase detection limits [43–45]. Further, Nanoparticles act as highly efficient carrier materials for enzymes for ideal properties of immobilization and balancing important factors that determine the efficiency of biocatalysts [46–52].

Environmental Contamination and Nanoremediation

Pollution and environmental protection are major global challenges that must be resolved as soon as possible. With a major role in pollution prevention, detection, monitoring, and remediation, nanoremediation is currently working to offer a fresh and successful solution for environmental clean-up [23]. Nano-remediation has lately been used in environmental remediation like water purification, waste water treatment, soil, groundwater, and oil spill remediation [23, 53–56], following the recent successful trend of utilising these biological systems, such as bioremediation, phytoremediation, and rhizoremediation [23]. For the remediation of a variety of pollutants, including chlorinated chemicals (PCE,TCE, DCE), hydrocarbons, pesticides (lindane, DDT), and heavy metals like arsenic and chromium, carbon nanotubes, nanofibers, and zero valent iron (nZVI) have all been utilized at the nanoscale to convert organic molecules like nitrates [23, 57, 58]. In certain cases, nanoparticles are combined with magnetic particles to aid in particle separation; they also serve as catalysts for the chemical or photochemical oxidation of pollutants [59, 60]. Nanoparticles are used as powerful adsorbents because of their strong adsorption capacity, high surface area to volume ratio, high surface reactivity and photo catalysis effect [60, 61] is based on detection methods of Raman Scattering, Surface Plasmon Resonance, Fluorescence detection, and Electrochemical detection [61]. However, effective use of this technique would require tight control over nanoparticle mobility, reactivity, and specificity for the target pollutant [54]. This enables harmful pollutants to be changed into less harmful, more biodegradable, and/or electrochemically reactive compounds [60, 61]. Heavy metals and organic contaminants can both be effectively treated by using the photo catalysis effect. Titanium dioxide (TiO2) and zinc oxide (ZnO) are large band-gap semiconductors that are used to reduce hazardous metal ions like Cr(VI), Ag(I), and Pb(II) and degrade organic compounds like chlorinated alkanes and benzenes, dioxins, and furans [57, 61–65]. ZnO nanoparticles have recently been demonstrated to function as a photo catalyst and sensor for the treatment of chlorinated phenols [62–64]. These particles are easily accessible, affordable, and barely harmful. In addition, functionalization of nanomaterials with chemical groups that can trap specifically targeted contaminants enables the detection of pesticides [61, 65]. However, it is necessary to assess, analyse, and contrast the potential environmental and health concerns connected to this next-generation technology with those of existing approaches [23, 59, 66] Environmental applications of nanotechnology focus on developing solutions for current environmental issues, protecting against potential risks posed by nanotechnology, as well as future problems brought on by interactions of energy and materials with the environment [23, 57, 58]. In short, nanotechnology has the ability to improve the environmental remediation process by reducing the creation of secondary by-products, degrading some hazardous pollutants through zero waste procedures, and preventing additional soil contamination by transforming the contaminants' labile to non-labile phases [61, 65] (Table 1).

Table 1.

List of nanomaterial and their applications in day to day life

Types of nanomaterials	Applications	References
Nanopesticides	Improvement of food texture & quality	[19–21]
Nanoherbicides	Improvement of food texture & quality	[19–21]
Nanofertilizers	Improvement of food texture & quality	[19–21]
Nanoscale zero valent iron (nZVI)	Remediation	[23, 53–58]
Carbon nanotubes	Remediation	[23, 26, 27, 57, 58]
	Solar panels
Nano-fibers	Remediation	[23, 53–58]
Titanium dioxide	Production of cosmetics	[57, 61–65]
	Reduce hazardous metal ions
	Degrade organic compounds
Zinc oxide	Production of cosmetics	[57, 61–65]
	Reduce hazardous metal ions
	Degrade organic compounds
Silver nanoparticles	Antibacterial properties	[34]
Gold NP	Sensor	[34–38, 40–42]
	Detector
Nanowires	Improve sensitivity	[43–45]
	Speed up response
	Increase detection limits
Nanotubes	Improve sensitivity	[43–45]
	Speed up response
	Increase detection limits
Nanoparticles	Improve sensitivity	[43–52]
	Speed up response
	Increase detection limits
	Carrier materials for enzymes
Nanocrystals	Improve sensitivity	[43–45]
	Speed up response
	Increase detection limits

Future Implications of Environmental Nanotechnology

A look at current nanotechnology and its area of applications clearly explains its diverse and complex implications. It is now well explained that since 2018, nanotechnology has made remarkable progress in the field of energy and resource efficiency, environmental remediation [67]. Further, its application in agriculture, water treatment, separation process, food and food packaging, and different areas of construction industries are also well explained [68].

Recent past has witnessed environmental nanotechnology playing a key role in solving several queries about the risks posed by nanotechnology and now exploring the ways to sustainable use of NMs for addressing hazards of other chemicals in the environment [69]. Environmental nanotechnology has also proved itself in recognizing the networks like water, soil, air etc. in which NMs are present and further influences their habits including dissolution, aggregation, toxicity etc. [70, 71]. A lot of analytical techniques including Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Atomic Absorption Spectroscopy (AAS), Dynamic Light Scattering (DLS) and many more are now available to measure the levels or estimate the concentration of NMs in sewage and treated wastewater effluents that enter the river. The low risk of NMs on human health make nanotechnology a beneficial process to purify drinking water or industrial wastewaters in the coming future [72, 73]. According to Westerhoff and group 2018 [74], NM can be used as an alternative to conventional water treatment processes for treating persistent pollutants as the traditional methods employs the usage of huge amounts of conventional treatment chemicals and large amounts of solid wastes.

Now-a-days, nanomaterials are in very high demand in the construction and building industry. In 2020, more than 800 nano based products used in construction are listed at global scale and many more are still waiting for their turn [73]. Very less light scattering properties make small particles a best option for transparent coating, hence pave a path for their use in glazing, anti reflection films, solar control films and coating on woods [75]. Having similar functionality to classical coating, nano based coating requires much less resource input and hence making them very promising applications of nanomaterials.

According to Mohajerani and group, 2019 [76] nanostructures are found suitable for providing strength to concrete. Also they improved mechanical strength and chemical durability while added to ultra-high performance concrete. It is also argued that in spite of all the benefits and efficiency of nanomaterials in construction, some barriers like cost, legislative issues, safety concern and lack of long term experience in the very conservative construction industry should be managed accordingly.

Sustainability, Ecological Risks and Environmental Ethics of Nanoparticles

Engineered nanomaterials provide fascinating prospects for applications in a variety of industries, including biomedicine, agriculture, environment by conserving energy, boosting crop yields and agricultural productivity, cleaning up contaminated soil and water, as well as lowering toxic metal waste and damaging greenhouse gas emissions [77, 78]. On the other hand, growing use of engineered nanoparticles in daily applications and their increased exposure to the environment and ecosystems disrupt the cycling of nanoparticles and raising the questions about environmental safety due to their possible negative and toxicological impacts on environment [77–80].The survival of important species of the ecosystem like bacteria, algae, fishes and plants may be directly impacted by engineered nanoparticles dispersed in the air, water, and soil [81, 82]. It is known that, engineered nanoparticles induce genotoxicity, cytotoxicity, and carcinogenicity in biological system [83]. Therefore, engineered nanoparticles must be cycled through the land, soil, and water using precise and efficient techniques and procedures [80]. However, current studies to assess the toxicity of engineered nanoparticles in vivo and in vitro are unable to accurately determine the type and extent of toxicity [81–87]. Thus to address the ecotoxicological issues related to engineered nanoparticles, a multidisciplinary approach incorporating experimental, computational, and theoretical techniques might be helpful [77–80]. Moreover, in order to sustainably protect our ecosystem, nations like the USA, Canada and Europe are changing their approach toward use of engineered nanoparticles in an appropriate and ethical manner [77, 79, 80].

Conclusion

While the complete potential of nanotechnology is still unknown, its commercialization and integration with biotechnology has already shown promise in addressing various environmental and human health issues. Scientists and researchers are just beginning to explore the potential positive impacts of nanotechnology on these fields. However, this growth has also prompted legal and regulatory authorities to ensure safe and responsible use of nanotechnology in scientific trials. Nanotechnology has already paved the way for new advancements in physics, energy, space sciences, pharmaceuticals, filtration, sensors, drug delivery, soil health rejuvenation, and more. The ability to manipulate atoms to form new structures has opened up new possibilities for scientific progress. With the correct application of nanoscience, environmental concerns may be significantly addressed in the near future. While there are still unanswered questions, one thing is certain: nanotechnology has changed the face of science forever.

Declarations

Conflict of interest

The authors declare no conflict of interest.