Nanotechnology and Its Applications in Environmental Remediation

Introduction

Environmental pollution is a grave challenge in contemporary society worldwide. It is aggravated by increased urbanisation and industrialisation in the manufacturing, mining, refining, transportation and construction sectors (Nyika, 2020a). These processes deplete land and water resources and lead to generation of massive hazardous wastes and pollutants that are public health and environmental threats. Examples of resultant contaminants include organic compounds, sewage, industrial effluents, toxic gases, oil spills, fertilisers, herbicides, pesticides, heavy metals and particulate matter just to mention a few. In addition, they affect human health once inhaled, ingested or absorbed directly and indirectly through food chains (Mehndiratta et al., 2013). The capacity of these pollutants to bioaccumulate and persist in the environment increases their pollution capacity.

In recognition of these trends, the urgency to develop cost efficient and sustainable toxin monitoring and treatment approaches is indispensable. A number of novel technologies are often researched on for remediation of soil, air and water contaminants. Additionally, a variety of materials are being applied for remediation considering that the capture and metabolism of contaminants is challenging due to their low reactivity, high volatility and the complexity of their mixtures that are difficult to isolate (Guerra et al., 2018; Nyika, 2020b). Nanotechnology is one of the most promising of these approaches to environmental remediation and recent research has intensified its focus in pollutant management.

Nanotechnology is a technique to produce systems, devices and materials of nanoscale that have important characteristics and functions that regulate the shape and size of matter (Ibrahim et al., 2016). According to Guerra et al. (2018), nanomaterials are more effective compared to conventional bulkier products, which gives them enhanced reactivity advantage and potential use in remediation. Furthermore, their exceptional surface chemistry facilitates the addition of functional groups that target specific molecules of pollutants to enable their breakdown and subsequent depollution. The capacity to tune the physical characteristics of nanoparticles including their porosity, morphology, size and chemical components offers advantages that enable effective remediation (Guerra et al., 2018). Nanomaterials are also preferred as they can be introduced to polluted environs directly and their removal is highly effective owing to their enhanced reactivity. Nanomaterials and nanocomposites are biodegradable and in that way, they do not become pollutants during remediation processes. This makes them greener, cleaner, non-hazardous, eco-friendly and safer in addition to being target precise. Specific examples of nanoparticles’ features include (Nyika, 2020a):

• ❖ They have the capacity to adsorb and absorb large quantities of contaminants due to their high surface energy and large surface area.

• ❖ They speed up reactions better than bulk material, which reduces energy consumption during degradation and impedes contaminant release in environs once absorbed or adsorbed.

• ❖ Nanotized particle forms enable easy access of contaminants in-situ as opposed to ex-situ during remediation processes.

• ❖ The particles can be coated with ligands to enhance surface area to volume ratio, modify the shape and design sensors of great specificity, sensitivity and selectivity to a given pollutant.

This book chapter explores the recent advances in nanotechnology use in environmental remediation using existent literature. The processes involved in nanotechnology-based remediation such as adsorption, catalysis and transformation and various materials used in the processes are highlighted.