Synthesis of ferroferric oxide@silicon dioxide/cobalt-based zeolitic imidazole frameworks for the removal of doxorubicin hydrochloride from wastewater

Due to its low-cost, eco-friendliness and easy mode of separation biosynthesized magnetic ferroferric oxide (Fe3O4) can be successfully used for the removal of organic contaminants from wastewater. However, there are some challenges that to date have limited this compound's practical removal efficiency. Thus, in this study, a cobalt-based zeolitic imidazole frameworks (ZIF-67) coated biosynthesized ferroferric oxide@silicon dioxide (Fe3O4@SiO2) magnetic composite (Fe3O4@SiO2/ZIF-67) was prepared to address these issues and subsequently used to remove doxorubicin hydrochloride (DOX). Characterization results showed that the fabricated composite exhibited significant magnetic properties (16.1 emu·g-1) with a size ranging between 50 and 250 nm. The amount of DOX adsorbed by the composite (90.7 mg·g-1) was much higher than either of the component parts, which were only 35.7 and 82.5 mg·g-1 for Fe3O4@SiO2 and ZIF-67 respectively. This indicated enhanced DOX adsorption by Fe3O4@SiO2/ZIF-67. The DOX adsorption best fit a pseudo-second order kinetic and Langmuir adsorption model. These studies suggested that the DOX adsorption mechanism involved a combination of electrostatic interactions, π-π stacking, hydrogen bonding and pore filling. Regeneration and application studies, exposing Fe3O4@SiO2/ZIF-67 to real water samples, practically demonstrated that Fe3O4@SiO2/ZIF-67 with propensity for magnetic separation and recycle is a promising nanomaterial for DOX removal.