Chapter 9 - Carbon nanomaterials-based sensors for water treatment

Abstract

Real data about raw and treated water quality is essential for both to determine the environmental impact and especial, to define the adequate process to treat water for human consumption, as well as to assess the process control and the performance. Detection of contaminating chemicals in the water treatment plants represents a great challenge, considering especially the priority and emerging pollutants due to the trace level of their concentration in water, at which the contaminants exhibit the high negative environmental impact and risk on the human health. The trace level detection of pollutants necessitates the improved analytical methods and electrochemical sensors have attracted considerable attention for the sensitive detection of a large variety of micro and emerging pollutants. The electrode material represents the core of the electrochemical sensors’ performance and carbon-based materials are the most common for the development of the voltammetric and amperometric sensors. Due to their limitations regarding the slow electron transfer kinetics, carbon-based nanomaterials have gained tremendous interest in the design of high-performance electrochemical sensor based on their exceptional mechanical, thermal, electronic, and catalytic properties. This chapter focuses on several designs of carbon nanomaterials, including carbon nanotubes (CNTs), carbon nanofibers (CNFs), fullerene (FULL), graphene (GR) and graphene quantum dots (GQDs), as different configurations of the electrode types (paste, epoxy-based composite, carbon nanomaterials-modified commercial carbon electrodes including silver nanoparticles) as sensing materials for the electrochemical detection of some representative priority and emerging pollutants among some conventional water pollutants (S2−, NO2−, NH4+). Pentachlorophenol (PCP) and pesticides (carbaryl and paraquat) and heavy metals (As (III) and Pb (II)) from priority pollutants and the pharmaceuticals from emerging pollutants classes were selected for comparative study and for the development of very sensitive amperometric and voltammetric detection methods. Role of carbon nanomaterials within the enhanced the electron transfer kinetics based on the electrocatalytic activity and/or the improved mass transfer considering the morphostructural properties is discussed related to the high-performance of the electrochemical sensor in water quality monitoring and the process control in water treatment technology. Also, the importance of the electrochemical techniques used in detection, such as: cyclic voltammetry (CV), differential-pulsed voltammetry (DPV), square-wave voltammetry (SWV), chronoamperometry (CA) and multiple-pulsed amperometry (MPA) are presented considering the operating parameters of each technique linked to the mechanistic aspects of the detection process. The potential for selective and/or simultaneous detection of several pollutants in water is presented. In addition, the existing limitations and future challenges are discussed in the context of practical application in water quality monitoring and water treatment technology.