Carbon Materials as Adsorbents for Organophosphate Pesticides in Aqueous Media - Critical Overview

Abstract

Organophosphates are considered some of the most toxic substances synthesized by man due to their high neurotoxicity. Their wide use in modern agriculture and other areas results in an urgent need for their efficient removal from the environment. Among numerous removal strategies, adsorption is considered a promising approach for organophosphate pesticide removal because it is simple, economical, and environmentally friendly. Carbon-based materials are a very good choice for this purpose because of their properties, including high specific surface areas, various pore structures, and rich surface chemistry. Furthermore, carbon materials not only have a high adsorption capacity towards organophosphates, but they are generally cheap, and their properties could be easily tuned. When analyzing the adsorption of organophosphates on carbon materials, the key is to understand the mechanisms of these interactions. However, available literature shows a great diversity in used approaches and sometimes diverges from basic theoretical principles. In this chapter, we critically address the analysis of organophosphates adsorption on carbon materials. First, we present the properties of organophosphate pesticides, followed by the classification of carbon materials and an overview of techniques used in their characterization. This is essential to understand how organophosphates can interact with carbon surfaces and what are the key factors determining adsorption performance. Next, we summarize thermodynamic and kinetic descriptions of adsorption processes and outline critical points in the analysis of adsorption thermodynamics. This is followed by an overview of organophosphate-carbon interactions and experimentally obtained adsorption capabilities of different carbons reported in the literature. We conclude with the suggestions to standardize adsorption measurements, making them easier to compare and suitable for extracting the key carbon properties for developing advanced superior adsorbents for organophosphate pesticides.