Theoretical evaluation of 17β-estradiol and 17α-ethinyl estradiol adsorption on reduced graphene oxide: Interactions, bonds, and energies

The 17 beta-estradiol (E2) and 17 alpha-ethinyl estradiol (EE2) are the main causes of estrogenic activities in aquatic bodies and sewage, mainly affecting the male and female reproductive systems, causing various disorders such as menstrual irregularities, infertility, endometriosis, polycystic ovary syndrome, spontaneous abortions and other illnesses. One technique for removing hormones from water bodies is using adsorption and the use of reduced graphene oxide (rGO) is interesting because rGO has excellent adsorption properties. In this context, the work aims to theoretically evaluate the interaction between 17 beta-estradiol (E2) and 17 alpha-ethinyl estradiol (EE2) with reduced graphene oxide (rGO) matrix. The frontier molecular orbitals and the molecular electrostatic potential showed that the interactions between the adsorbate-adsorbent can occur through hydrogen bonds, -H ... pi and pi ... pi interactions. The binding energy values showed that the interaction can occur, the enthalpies that the process is exothermic and the Gibbs energy that only the adsorption of E2 hormones with the rGO matrix is spontaneous. The classical hydrogen bonds vary between 1.924 & Aring; and 2.781 & Aring;. The topological parameters showed that almost all interactions are electrostatic, and non-covalent interaction analysis indicated the presence of Van der Waals interactions predominantly. In this way, it can be confirmed that the study showed the efficient use of the rGO matrix for the treatment of effluents that contain the hormones E2 and EE2.