<p>Water pollution containing high concentrations of organic pollutants such as nitrothal-isopropyl and endosulfan is a serious concern in the environment because both are implicated in the eutrophication of receiving water. Nitrothal-isopropyl and endosulfan are two main organic pollutants that cause water eutrophication. In this study, modified coffee grounds-diethylenetriamine (MCG-DETA) nanocomposites used as a strong bio-adsorbent for the removal of nitrothal-isopropyl and endosulfan from wastewater were investigated. The aim of this study is to recycle coffee grounds and prepare MCG-DETA nanocomposites for the adsorption of nitrothal-isopropyl and endosulfan compounds. Nitrothal-isopropyl has an optimal adsorption capacity of 35.74&#xa0;mg/g, while endosulfan has an optimal adsorption capacity of 19.21&#xa0;mg/g. For nitrothal-isopropyl and endosulfan adsorption, the Freundlich isotherm model was suitable. MCG-DETA can serve as a potential low-cost adsorbent to remove nitrothal-isopropyl and endosulfan organic pollutants from wastewater. According to density functional theory calculations, electrostatic interactions between nitrothal-isopropyl and endosulfan with modified coffee grounds were verified. DFT calculation reveals that the calculated adsorption energy of nithrothal-isopropyl is -0.349&#xa0;eV which is greater than that of endosulfan, -0.219&#xa0;eV. The highest possibility of the attraction between modified coffee grounds and nitrothal-isopropyl was between -COOH in modified coffee grounds and -NO₂ in nitrothal-isopropyl. In addition, the attraction of modified coffee grounds and endosulfan is due to the COOH and NH₂ in modified coffee grounds and sulfonyl and halide in endosulfan. This effort enhanced researchers' thoughtfulness in the elimination of the mentioned organic pollutants from wastewater by using MCG-DETA nanocomposites experimentally and theoretically via density functional theory.</p>