Treatment of adsorption of dioxane by using SiCNT toward efficient remediation of refractory organic contaminants from wastewater: DFT and DFTB-MD simulations

Abstract Dioxane contaminant as a serious environmental issue is extensively found in industrial wastes, hence its remediation is highly necessary. Herein, we investigate the effective adsorption and elimination of 1,4-dioxane by SiCNT. DFT-D3/revPBE calculations showed that both dioxane and water molecules interact strongly with exterior surface of SiCNT but dioxane tends to be adsorbed stronger than water molecule with difference adsorption energy of 10 kcal/mol. In addition, dioxane could be strongly adsorbed into the SiCNT cavity. Our employed DFT calculations was validated against the high-level MP2 method. A series of analyses was performed on the explanation of the particular molecular factors and scientifically creditable relationships of interaction nature and interfacial region of systems under study. The AIM theory analyses revealed that the strong interactions raised from the existence of simultaneous polar attraction as well as partially covalent bond between O and Si atoms. Meanwhile, the difference in adsorption strength could be attributed to higher long-range dispersion attractions observed for dioxane/SiCNT. Furthermore, the adsorption capability and selectivity of dioxane by SiCNT was explored by DFTB-MD simulation in the presence of water molecules at ambient conditions. The recovery time calculated by DFT-D3 method revealed that however, pure SiCNT might not to be recovered from the dioxane/SiCNT system. The appropriate adsorption strength and selective adsorption of dioxane by SiCNT lead to practically apprehension of this novel nanotube as suitable adsorbent for dioxane but its weakness recovery time as a disadvantage is not desirable.