Natural halloysite nanotubes (HNTs) have attracted great interest as smart nanocontainers of corrosion inhibitors. The adsorption behavior of corrosion inhibitors on HNTs will affect their loading capacity, a crucial property of smart nanocontainers. This work modified the surface of HNTs by preadsorbing metal cations (M2+: Fe2+, Zn2+, or Cu2+) to improve the adsorption of benzotriazole (BTA) on HNTs. The results based on the thermal gravimetric analysis showed that the loading capacities of BTA in Fe2+-, Zn2+-, and Cu2+-adsorbed HNTs were 8.25, 8.39, and 9.74 wt %, respectively, which are significantly higher than those in pristine HNTs of 4.57 wt %. Furthermore, density functional theory calculations exhibited that the adsorption energies of BTA on the M2+-adsorbed surfaces increased compared to that on the clean surface. Notably, the increasing trend of adsorption energies is in good agreement with that of measured loading capacities. Moreover, the presence of metal cations significantly enhances the charge transfer between BTA and the surface. The density of states analysis indicated that the adsorbed metal cations shifted the valence bands of the surface close to the Fermi level, thereby enhancing the coupling between the occupied bands of HNTs and the unoccupied orbitals of BTA.

In this study, the author formulated the equation that describes the reaction rate (mathematical modelling) of 2,4,6-trinitrotoluen and hydroxyl radical (OH*) of v = 4.3×108×[CTNT]1.1×[COH*]3.2 and mathematical simulation for the reaction process of 2,4,6-trinitrotoluen and OH* radical. The simulation results showed a decrease in concentration [CTNT] and a reaction rate proportional to each other; during the first 0-30 minutes of the reaction, the reaction speed is very fast. From the experimental results, the authors also determined that the 2,4,6-trinitrotoluen treatment performance in wastewater of the nonthermal plasma model reached >99% when increasing the treatment time to 120 minutes.