Synthesis of Magnetic Fe3O4 Nano Hollow Spheres for Industrial TNT Wastewater Treatment

The aim of the present work was to synthesize magnetite (Fe3O4) nano hollow spheres (NHS) via simple, one-pot, template-free, hydrothermal method. The structural, morphological, and surface analysis of Fe3O4 NHS were studied by scanning electron microscopy (SEM), x-ray diffraction technique (XRD), Fourier transform infrared spectroscopy FTIR and burner-Emmett-teller (BET). The as obtained magnetic (Fe3O4) NHS were used as an adsorbent for treating industrial trinitrotoluene (TNT) wastewater to reduce its Chemical Oxygen Demand (COD) values. Adsorption capacity (Qe) of the NHS obtained is 70 mg/g, confirming the attractive forces present between adsorbent (Fe3O4 NHS) and adsorbate (TNT wastewater). COD value of TNT wastewater was reduced to >92% in 2 h at room temperature. The adsorption capacity of Fe3O4 NHS was observed as a function of time, initial concentration, pH, and temperature. The applied Fe3O4 NHS was recovered for reuse by simply manipulating its magnetic properties with slight shift in pH of the solution. A modest decrease in Qe (5.0-15.1%) was observed after each cycle. The novel Fe3O4 NHS could be an excellent candidate for treating wastewater generated by the intermediate processes during cyclonite, cyclotetramethylene-tetranitramine (HMX), nitroglycerin (NG) production and other various environmental pollutants/species.

Automated summary

This study synthesized magnetite nano hollow spheres using a simple, one-pot, template-free hydrothermal method. The obtained spheres demonstrated excellent adsorption capacity for treating trinitrotoluene wastewater and reducing its COD value. The spheres could be easily recovered and reused with only a slight decrease in adsorption capacity after each cycle.