###### Abstract  
(1) Background: The development of highly efficient methods for removing hazardous substances from the environment attracts increasing attention. Understanding the basic principles of the removal processes using graphene materials is equally essential to confirm their application efficiency and safety. (2) Methods: In this contribution, adsorption of pesticide dimethoate (DMT) on graphene-based materials has been investigated on the molecular level. (3) Results: The experimental results' analysis revealed a cooperative binding mechanism of the DMT on the adsorption sites of investigated materials--graphene oxide (GO) and industrial graphene (IG). The adsorption data were analyzed using various adsorption isotherms to determine the thermodynamics of the adsorption process. The experimental results were correlated with Density Functional Theory (DFT) calculations of DMT adsorption on the model surfaces that appropriately describe the graphene materials' reactive features. (4) Conclusions: Considering experimental results, calculated adsorption energies, optimized adsorption geometries, and electronic structure, it was proposed that the dispersive interactions determine the adsorption properties of DMT on plain graphene sites (physisorption). Additionally, it was shown that the existence of vacancy-type defect sites on the surfaces could induce strong and dissociative adsorption (chemisorption) of DMT. graphene; dimethoate; adsorption isotherms; adsorption energy; DFT +
Footnote †: journal: Medical  
Graphene-based materials have been extensively studied as adsorbents in past years [18; 19] and have shown considerable effectiveness in removing organic and inorganic contaminants. In our recent paper [20], three graphene-type materials have been tested as adsorbents for OPs pesticides dimethoate (DMT) and chlorpyrifos (CPF). The spectroscopic analysis of graphene oxide (GO) and industrial graphene (IG) in this study includes Raman XRD, XPS (C 1s and O 1s spectra), and FTIR methods. IG has a high specific surface area (SSA), 600 m\({}^{2}\) g\({}^{-1}\), with a relatively small concentration of oxygen functional groups and effectively separated graphene layers. However, the aggregation of graphene sheets cannot be excluded. GO with SSA of 10 m\({}^{2}\) g\({}^{-1}\) has a highly disordered structure and low fraction of sp\({}^{2}\) hybridized carbons due to a large concentration of different oxygen functional groups attached to its surface. Due to a large concentration of oxygen functional groups, this material is highly hydrophilic and easily dispersed in water with effectively separated sheets and the broadcast material. The XPS method confirmed a significant variation in the C/O ratio among the studied adsorbents and GO with almost 30 at% oxygen. The adsorbent, denoted as IG, contains approximately 6 at% oxygen and a largely preserved \(\pi\) electron system. The extensive characterization of the material structure and adsorption efficiency revealed that relatively subtle differences in adsorbent structure (e.g., the distance between graphene sheets and surface concentration of defects) could bring vast differences in adsorption efficiency by a few orders of magnitude [21]. Such a result emphasizes a need for a deeper understanding of the adsorption properties and mechanism of adsorbent-adsorbate interaction to assure functionality and predict optimal adsorbent properties for the application. The involvement of theoretical chemistry methods and the development of reliable theoretical and empirical models to describe adsorption is crucial at this point of research [22; 23; 24]. This contribution aimed to elucidate the adsorption mechanism and analyze thermodynamical properties of the interaction between OP DMT and two types of commercial graphene surfaces, industrial graphene (IG) and graphene oxide (GO).