An Insight into the Efficient Dimethoate Adsorption on Graphene-Based Materials—A Combined Experimental and DFT Study

Vladan J Anićijević,Tamara D Lazarević-Pašti,Vesna M Vasić,Dragana D Vasić Anićijević

doi:10.3390/app11094014

Vladan J Anićijević, Tamara D Lazarević-Pašti + Show 2 more

Open Access

https://doi.org/10.3390/app11094014

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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.

Highlights

Organophosphates (OPs) are among the most toxic substances to humans ever known due to their ability to irreversibly inhibit enzyme acetylcholinesterase (AChE), which has a substantial role in the transmission of neuronal impulses by the cholinergic neurons, being present in both peripheral and central nervous system [1,2]
We used the approximation of the bimolecular interaction between biological macromolecules and the ligand, considering DMT as the ligand and adsorbents as macromolecules with several binding sites [36,37]
The theoretical maximal concentration of binding sites (BS) for DMT on macromolecules (CBS-total ) corresponds to the complete monolayer covering with the ligand and is expressed as the molar concentration of BS per g of graphene material

Summary

Introduction

Organophosphates (OPs) are among the most toxic substances to humans ever known due to their ability to irreversibly inhibit enzyme acetylcholinesterase (AChE), which has a substantial role in the transmission of neuronal impulses by the cholinergic neurons, being present in both peripheral and central nervous system [1,2]. Recent studies have confirmed that extensive use of OPs induces drinking water contamination in various agricultural areas worldwide [3,4]. In this view, finding reliable methods for removing them from the environment is a matter of general interest. There is emerging research dealing with the various methods for their removal from contaminated water, including physicochemical methods (adsorption, electrochemical oxidation, and photocatalytic degradation) [5,6,7,8], chemical oxidation [9,10,11,12], and biological degradation [13,14,15,16]. Adsorption is attractive for research and application, as it is simple to apply, economical, and environmentally friendly, since no additional toxic chemicals are used [17]

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