Use of Nanoparticles for Environmental Remediation

Introduction

Soil, water, and air are the most precious components of the living world. They perform the most significant functions like life supports, biodiversity conservation, carbon storage, food production, etc. To attain sustainable development requires a safe, healthy and productive environment. However, our environment is under serious threat of pollution. Pollution can be defined as the presence and persistence of toxic and hazardous substances into the environment. The concentration of the pollutants must be present in the environment below the threshold limit; beyond these limits, it can be harmful to the living world. Over the last decades, to fulfill the needs and demands of the growing populations, rapid industrializations, various developmental processes, and synthetic chemicals in agriculture continuously release waste as a by-product and pollute the environment. The release of toxic contaminants hinders the soil environments and also disturbs the aquatic environments(Ukaogo et al., 2020). The toxic contaminants from the environment slowly make entry into the food chain and cause various complications in the living world. Excessive concentration of the pollutants in the environment, their interactions, and accumulation into the plants disturb plants' growth and developmental processes and ultimately reduce yield and productivity and sometimes cause death. The reduction in plant productivity and the exponential growth of the human population are some of the reasons for upcoming risks of food security(Rojas et al., 2016; Sun et al., 2017).

Thus, exclusion and counteracting the pollutants from the environment is necessary to develop a safe and productive environment. Currently, numerous techniques are used to remediate contaminants from the environment; but the techniques are not still enough for complete remediation of current and upcoming environmental contaminants. In parallel, the rapid advancement in nanotechnology has gained increased attention to the use of nanoparticles (NPs) for environmental applications. Nano-remediation is currently attempting to provide a novel and practical solution for the abatement of contaminants from the environment by employing an important role in source reduction, detection, monitoring, and remediation. Nano-remediation has the ability to conquer some challenges in environmental cleanup by increasing the overall efficiency of the remediation process in a cost-effective manner. However, the currently available wastewater and soil remediation techniques like surfactant co-solvent flushing, chemical oxidation, soil washing, thermal treatment, etc. are quite expensive, partially effective, and time-consuming; and hence, could be slowly get rid of over the time. In this case, nano-remediation technique has received a wide range of research acceptance as well as practical implications due to its effectiveness, rapidity, and eco-friendly as well as budget-friendly behaviour (Patil et al., 2016).

Nano-remediation techniques use nano sized particles like zeolite, nano-fibre, carbon nanotubes, metallic oxides, bimetallic NPs, etc. for the abatement of pollutants. US EPA 2004, reported 44 locations across the seven countries where nano-remediation techniques have been found successful for abatement of contaminants from contaminated sites. It has been found that the nano-remediation techniques reduce the overall cost as well as time frame as compared to the conventional remediation techniques (Patil et al., 2016; US EPA, 2004). In recent years, NPs are widely used to abate contaminants from the environment(Guerra et al., 2018). NPs possess high reactivity with large and specific surface areas and hence act as sensors, catalysts, and adsorbents. The large surface area to mass ratio enhances the adsorption capabilities of NPs. Similarly, the large radii of curvatures and the reduced size provide NPs a highly reactive surface. Additionally, the mobility of NPs is very high due to their small size and can be reached at any part of the medium. These unique properties of NPs make them the most efficient tool for environmental remediation(Khan et al., 2019).

Nanotechnology now becomes a known area of research providing diverse applications. Nanotechnology produces various nanoscale NPs that can be used in medicine, agriculture, environmental protection, etc. This chapter will provide a brief idea on the need for remediation and the use of NPs for environmental remediation to the students and also help the researchers as a thorough reference to understand the current research trends and the complications to find future research questions. Additionally, the complications and current research trends of using NPs in environmental remediation are briefly discussed for determining future research prospects.