Synthesis of a novel hierarchical pillared Sep@Fe3O4/ZnAl-LDH composite for effective anionic dyes removal

Abstract

A novel magnetic hierarchically pillared Sep@Fe3O4/ZnAl-LDH composite was successfully synthesized via co-precipitation methods. The prepared Sep@Fe3O4/ZnAl-LDH composite were characterized via FTIR, XRD, XPS, SEM, TEM, BET and VSM. The results show that the Sep@Fe3O4/ZnAl-LDH composite have a hierarchical columnar structure with nanoscale structural unit (Fe3O4/ZnAl-LDH) and overall micron-scale morphology, and the obtained graded adsorbent has a large pore capacity and pore size distribution. The maximum adsorption capacities of the obtained samples for methyl orange ( MO) and Congo red ( CR) were 430 mg·g−1 and 832 mg·g−1, respectively. Kinetic data of MO and CR adsorbed on as-prepared samples can well fit with pseudo-second-order model. The isothermal data of MO and CR adsorbed on Sep@Fe3O4/ZnAl-LDH match well with the Langmuir model. The thermodynamic results indicate that the adsorption process is spontaneous and endothermic. Besides, the adsorbent shows good stability and reproducibility in a reusable cycle. This study demonstrated that Sep@Fe3O4/ZnAl-LDH provides a new idea for the development of a novel hierarchical magnetic pillared adsorbent for the efficient removal of anionic dyes.