Molecular dynamics simulation of novel diamino-functionalized hollow mesosilica spheres for adsorption of dyes from synthetic wastewater

Abstract We studied the facile synthesis, design, simulation, and modeling of novel diamino-functionalized hollow mesosilica spheres (DAF-HMSS) structures to remove Neutral Red (NR) and Crystal Violet (CV) from aqueous media. The synthesized sample was characterized by FESEM, TEM, LXRD, BET-BJH, and FTIR techniques. The adsorption and removal mechanism of these hazardous dyes on DAF-HMSS in the presence of water molecules was studied using molecular dynamics simulation. The equilibrium adsorption capacities of DAF-HMSS were computed via the conductor-like screening models with segmented activity coefficients known as COSMO-SAC. Simulation results of optimization by Dmol3 showed that adsorption of CV dye by diamino groups of DAF-HMSS is more active in comparison with NR dye. Reactivity of molecules, chemical hardness (η), global softness, and electrophilicity index (ω) of compounds were assessed using the HOMO–LUMO gap. The Sigma profiles of DAF-HMSS with dyes showed that mesoporous adsorption of CV was more than NR while HOMO–LUMO energy gap of CV dye was less than NR. So, the chemical reactivity, chemical softness, and polarizability of CV dye were more than that of water and NR. Meanwhile, the kinetic stability of NR was more than CV dye. Besides, results of electrophilicity index (ω) exhibited high electrophilicity index of CV dye which indicates high toxicity of this dye.