In-depth targeted removal of Cu(II) by functionalized graphene oxide/sodium alginate composite aerogel: Coupling of two-dimensional confinement and bridging effect.

In this study, based on the planar configuration of hydrated copper ions, the "O-N-S" ternary cooperative system and two-dimensional slit-like pores were established in graphene oxide/sodium alginate composite aerogel (GSA) by functional group modification. As a result, the deeply coupling of bridging effect and confinement effect were achieved, aiming to achieve selective adsorption of low-concentration Cu(II) (removal efficiency: 99.34 %, adsorption capacity: 173.56 mg·g). The adsorption states of -OH, -NH and -SOH on Cu(II) were calculated and simulated by density functional theory. It was revealed that the sulfur atom effectively alleviated the electron localization degree of the combination of boundary acid ion (Cu(II)) with hard base group (-OH or -NH) due to its loose electron cloud. And the low-energy level electrons carried by -NH were used to synergistically enhance the covalentity of the "O-N-S" ternary cooperative system in GSA to ensure the selectivity and stability of Cu(II) adsorption. According to the excellent degradation effect of Cu(II) saturated adsorbent (GSAC) on enrofloxacin and the low Cu(II) leaching rate, the long-term stable adsorption of Cu(II) by the cooperative system was verified. The above research will provide theoretical reference and design scheme for the targeted removal of specific pollutants in complex water bodies.