ZIF-8 modulated synthesis of iron oxide @ poly(m-phenylenediamine) (Z) particles (Fe3O4@PmPD(Z)) for the removal of Cr(VI) from wastewater

Abstract

Iron oxide @ poly(m-phenylenediamine) (Z) particles (Fe3O4@PmPD(Z)) were synthesized by in-situ polymerization of PmPD on the Fe3O4 nanoparticles via ZIF-8 intermediate platform to remove Cr(VI) from wastewater. Analyses of FT-IR, TEM, etc. were performed to evaluate the morphology and structure of synthesized material, and the results confirmed the successful synthesis of Fe3O4@PmPD(Z). In addition, the TEM and BET analyses results show that the PmPD shell is a flocculating structure, and the increased specific surface area increases the contact with Cr(VI). The Fe3O4@PmPD(Z) exhibits much better Cr(VI) adsorption performance than Fe3O4@PmPD, and its adsorption capacity is increased by about 30%, the maximum Cr(VI) adsorption capacity can reach 371.75 mg g−1 at 318 K. According to FT-IR, XPS, and EDS, the removal mechanisms can be attributed to the redox reaction of Cr(Ⅵ) and NH to form N and Cr(Ⅲ), and N shares electron pair with Cr(Ⅲ) to form chelation. At the same time, the appearance of N+ also contributes to the removal of Cr(Ⅵ) by generating electrostatic attraction with the negatively charged HCrO4-. Besides, the Fe3O4@PmPD(Z) also exhibits excellent properties of recovery and reuse. Therefore, the current work proves that Fe3O4@PmPD(Z) has the potential to remove heavy metals in wastewater.