Efficient adsorptive removal of tetracycline from aqueous solution using phytosynthesized nano-zero valent iron

Abstract

Recently, nano-zero valent iron (nZVI) has been identified as one of the most promising materials for the removal of a wide range of pharmaceuticals in water. However, nZVI effectiveness in aqueous media is dramatically reduced due to its aggregation and instability. To overcome these problems, castor oil (Ricinus communis Linn.) leaves aqueous extract has been used in this study as a reducing and stabilizing agent to increase the stability of nZVI. The fabricated RCL-nZVI was well characterized using several spectroscopic techniques, e.g., steady-state absorption and fluorescence, SEM, TEM, FTIR, EDS, XRD, XPS, and zeta potential. The green phytosynthesized RCL-nZVI was examined in the adsorptive removal of tetracycline (TC). It was interesting to see that the removal efficiency of TC by RCL-nZVI reached 98% at pH 6 and 25 °C. The efficient removal of TC from the aqueous solution was in accordance with the pseudo-second-order kinetic model and well fitted to Langmuir model with a maximum adsorption capacity of 72.64 mg. g−1. In this study, a plausible removal mechanism was discussed, which primarily involves both adsorption and reduction pathways.

Keywords

• Phytosynthesis
• Ricinus communis
• nZVI
• Tetracycline
• Adsorption