Polydopamine (PDA) functionalized ultrathin carbon layer encapsulated magnetite nanoparticle and graphene oxide (Fe3O4@C-GO@PDA) as recyclable and stable nanoadsorbent for enhanced removal of metal ions

Efficiently eliminating metal ions from water remains a formidable challenge, primarily because of the intricate nature of impurities within the aqueous environment. In this study, magnetite nanoparticles encapsulated by an ultrathin carbon layer and graphene oxide (Fe 3 O 4 @C-GO) nanocomposite was further functionalized with polydopamine (PDA) to prepare Fe 3 O 4 @C-GO@PDA nanoadsorbent with improved adsorption capabilities for the effective elimination of metal ions from aqueous solutions. The Fe 3 O 4 @C-GO@PDA nanoadsorbent showed outstanding adsorption potential. Under the optimal the experimental conditions, the Fe 3 O 4 @C-GO@PDA nanoadsorbent effectively removed Zn(II), Cu(II), Pb(II), and Cd(II) ions from aqueous solutions at pH 6, with rates of 99.1 %, 97.7 %, 94.6 %, and 91.1 %, respectively. In comparison with Fe 3 O 4 @C-GO nanocomposite, the removal rate, removal capacity and removal equilibrium time of Pb on Fe 3 O 4 @C-GO@PDA nanoadsorbent all showed a great improvement. The adsorption of Pb(II) follows pseudo-second-order kinetics (R 2 = 0.9993), indicating that chemical adsorption is the dominant mechanism. XPS and FTIR analyses revealed synergistic interactions between Pb(II) and surface functional groups (–NH₂, C O, –COOH). The slightly decrease in the the removal rate in the recovery and recyclability investigations after 5 cycles indicated that Fe 3 O 4 @C-GO@PDA nanoadsorbent can be repeatedly used for the removal of for Zn(II), Cu(II), Pb(II) and Cd(II) ions from water. As a result, the Fe 3 O 4 @C-GO@PDA nanoadsorbent not only realize the removal of Pb ions from water with efficient removal but also show potential application in the separation and purification of other common metal ions.