Nanoscience and nanotechnology can produce materials with extraordinary properties and functionalities, revolutionizing various industry segments, particularly in nanotoxicology and nanosafety for environmental applications. Different nanostructures and classes of nanomaterials are notable for their wide range of practical applications, particularly in adsorption processes. Carbon nanomaterials (CNMs) exhibit intriguing structures with great potential for developing highly selective and efficient adsorbent systems. These nanomaterials can effectively remove inorganic, organic, and biological contaminants from the environment. Similarly, GaN nanotubes (GaNNTs) have been used as sensors and filters due to their high sensitivity to specific pollutants, such as gases, heavy metals, and organic compounds. This chapter presents studies involving nanostructures as adsorbents for removing the herbicide glyphosate (GLYPGlyphosate), such as GaNNT and graphene oxide (GO), through ab initio studies using Density Functional Theory (DFT). Furthermore, literature studies from recent years are reported, addressing the fundamental aspects of the use of ab initio methodologies in the perception of nanotoxicity in the environment and for removing contaminants from water, such as the distinction between physical and chemical adsorption.