The main challenge in the use of synthetic dyes and microplastics is their release into water resources, which has adverse effects on human health and the ecosystem. Hence, adsorption removal has been considered an efficient treatment method for pollution remediation from wastewater and industrial effluents. Metal-organic framework/graphene oxide composites can be effectively used for wastewater treatment. In the present study, the uptake mechanism of the cationic dyes, Methylene Blue (MB) and Rhodamine B (RhB), as well as Polyurethane (PU) microplastic by IRMOF-1 based on reduced graphene oxide (IRMOF-1/rGO) nanocomposite was comprehensively evaluated using molecular dynamics (MD) simulation. The contaminant molecules can be adsorbed on the designed nanocomposite to some extent, and which adsorbent exhibits an obvious preference for removing MB over RhB/PU and selectivity. In the case of cationic dyes, the accumulation of textile molecules is observed near the surface of reduced graphene oxide, whereas the metal-organic framework component illustrates a significant uptake capacity for PU microplastic. The tendency of PU microplastics to form a self-organized pattern is noticed in the PU@IRMOF-1/rGO system, but this tendency is less with the coexistence of MB in the mixed system. Increasing the dispersion of microplastic in the mixed system leads to an enhancement in the solvent-accessible surface area of PU from 40.60 nm2 in the individual system to 46.50 nm2 in the mixed system, respectively. It is found that the π-π conjugation, pore-filling effect, van der Waals, and electrostatic interactions govern the water purification mechanism by designed nanocomposite. This work gives a more detailed insight into the use of IRMOF-1@rGO nanocomposite as an effective technology for the decontamination of toxic dyes and microplastics from wastewater.

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