Multiscale computational simulation of pollutant behavior at water interfaces

The investigation of pollutant behavior at water interfaces is critical to understand pollution in aquatic systems. Computational methods allow us to overcome the limitations of experimental analysis, delivering valuable insights into the chemical mechanisms and structural characteristics of pollutant behavior at interfaces across a range of scales, from microscopic to mesoscopic. Quantum mechanics, all-atom molecular dynamics simulations, coarse-grained molecular dynamics simulations, and dissipative particle dynamics simulations represent diverse molecular interaction calculation methods that can effectively model pollutant behavior at environmental interfaces from atomic to mesoscopic scales. These methods provide a rich variety of information on pollutant interactions with water surfaces. This review synthesizes the advancements in applying typical computational methods to the formation, adsorption, binding, and catalytic conversion of pollutants at water interfaces. By drawing on recent advancements, we critically examine the current challenges and offer our perspective on future directions. This review seeks to advance our understanding of computational techniques for elucidating pollutant behavior at water interfaces, a critical aspect of water research.

Doping matters in carbon nanomaterial efficiency in environmental remediation

Carbon nanomaterials (CNMs) are rapidly emerging in materials science research due to their widespread environmental applications. They are useful for environmental pollutants' remediation through various methods. Heteroatom doping resulted in reliable approaches to overcome pristine CNMs challenges. The engineering of the dopants is believed to be a promising route to improve the efficiency of CNMs in environmental remediation. The idea of doping has been attractive since it allows the control of electronic properties due to the electron transfer between dopants and the host material and the dopants along with the bonding between analogous atoms and carbon atoms. This mini-review, through computational and experimental studies, puts special emphasis on the role of doping different CNMs as an efficient approach to enhance the environmental remediation.

Expanding the environmental applications of metal (Al, Ti, Mn, Fe) doped graphene: adsorption and removal of 1,4-dioxane

The potential applications of Al, Ti, Mn and Fe-doped graphene for environmental remediation of 1,4-dioxane (a critical pollutant and toxic compound) are analyzed in detail in the framework of density functional theory calculations. 1,4-Dioxane is a highly mobile and soluble pollutant and developing new strategies for its adsorption and subsequent removal becomes an important issue. All the systems were fully optimized and analyzed in their most stable spin states. The results determined that the proposed doped-graphene materials enhance the interaction with 1,4-dioxane compared to intrinsic graphene, with adsorption energies in the range of 1.2-1.6 eV. The high stability of the adsorbent-dioxane interactions is fully discussed in terms of chemical metal-dioxane binding, charge transfer and long-range interactions. The adsorbent-dioxane adsorption is also accompanied by changes in the electronic structure with respect to the isolated substrates, which are larger for Mn and Fe as dopants. Ab initio molecular dynamics simulations also show that the adsorbent-adsorbate interactions remain strong at room temperature (300 K). Finally, implicit/explicit solvent methodologies were implemented to get insights into the effects of aqueous environments on the adsorption strength, which shows the high stability of interaction in water, sorting the sorption efficiency as AlG ≈ FeG > MnG ≈ TiG. From these new insights, Al, Ti, Mn and Fe-doped graphene emerge as new potential materials to be applied in technologies related to the removal of 1,4-dioxane.

Adsorption/desorption process of formaldehyde onto iron doped graphene: a theoretical exploration from density functional theory calculations

The interaction of formaldehyde (H₂CO) onto Fe-doped graphene (FeG) was studied in detail from density functional theory calculations and electronic structure analyses. Our aim was to obtain insights into the adsorption, desorption and sensing properties of FeG towards H₂CO, a hazardous organic compound. The adsorption of H₂CO was shown to be energetically stable onto FeG, with adsorption energies of up to 1.45 eV and favored in different conformations. This interaction was determined to be mostly electrostatic in nature, where the oxygen plays an important role in this contribution; besides, our quantum molecular dynamics results showed the high stability of the FeG-H₂CO interaction at ambient temperature (300 K). All the interactions were determined to be accompanied by an increase in the HOMO-LUMO energy gap with respect to the isolated adsorbent, indicating that FeG is highly sensitive to H₂CO with respect to pristine graphene. Finally, it was found that external electric fields of 0.04-0.05 a.u. were able to induce the pollutant desorption from the adsorbent, allowing the adsorbent reactivation for repetitive applications. These results indicate that FeG could be a promising candidate for adsorption/sensing platforms of H₂CO.

Oxidized and Si-doped graphene: emerging adsorbents for removal of dioxane

The adsorption properties of oxidized graphene (GO) and Si-doped graphene (SiG) towards 1,4-dioxane were theoretically characterized.