One-Pot Synthesis of a Two-Dimensional Porous Fe3O4/Poly(C3N3S3) Network Nanocomposite for the Selective Removal of Pb(II) and Hg(II) from Synthetic Wastewater

Two-dimensional (2D) nanomaterials have attracted wide attention for heavy metal adsorption applications, yet the synthesis processes for this kind of nanocomposite are usually complex and generate lots of chemical waste. Herein, a facile one-pot synthesis of 2D porous magnetic poly(trithiocyanuric acid) nanocomposite (Fe3O4/poly(C3N3S3)) was successfully performed through the coprecipitation of ferrous and ferric ions and the subsequent in situ disulfide (-S-S)-linked polymerization reaction. The prepared Fe3O4/poly(C3N3S3) nanocomposite exhibits a 2D porous network structure, in which Fe3O4 nanopartides and clusters were embedded in the backbone of the poly(C3N3S3) network, reinforcing the joints of the 2D porous network structure and thus enhancing the interface and reusability of the nanocomposite. The effects of the solution pH, contact time, and metal concentrations on the adsorption process have been systematically investigated. The 2D porous Fe3O4/poly(C3N3S3) network presented high adsorption capacities for both Pb2+ (232.6 mg/g) and Hg2+ (344.8 mg/g) at optimum pH 6, since the functional group (C3N3S3) for metal adsorption is the building block of the poly(C3N3S3) network. The results of competitive adsorption tests indicated that this nanocomposite is a potent adsorbent for both Pb(II) and Hg(II) even in the presence of coexisting ions such as Mg(II), Ca(II), Zn(II), and Cu(II). The reusability experimental results suggested that weak links on the 2D porous Fe3O4/poly(C3N3S3) network broke up due to external stirring (shear force) while the main structure of this network was a solid construction, maintaining 65.5% and 71.2% of initial adsorption capacities for Pb(II) and Hg(II), respectively, after 7 consecutive cycles.