The role of bio-inspired ZnO nanoparticles in the modification of MIL101(Cr) properties for visible light degradation of phenanthrene
Usman Abubakar Adamu, Noor Hana Hanif Abu Bakar, Anwar Iqbal, Nonni Soraya Sambudi, Zakariyya Uba Zango
Abstract
MIL-101(Cr) metal-organic frameworks and novel zinc oxide-MIL101(Cr) metal organic frameworks (ZnO-MIL101(Cr)) were prepared by hydrothermal technique at 160 °C and 220 °C for photodegradation of phenanthrene (PHE) in visible light. X-ray diffraction (XRD) analysis indicated a reduction in crystallite sizes of ZnO-MIL101(Cr) when compared to MIL101(Cr). However, incorporation of zinc oxide (ZnO) did not disrupt the MIL101(Cr) structure. ZnO-MIL101(Cr) exhibited high BET surface area (>1000 m2/g) when compared to MIL-101(Cr). These composites have lower bandgaps of ~3.20 eV, than MIL-101(Cr) (3.5 eV). Optical studies reveal that incorporation of ZnO into MIL101(Cr) delays recombination of electron-hole pairs. These factors lead to ZnO-MIL101(Cr) having similar PHE degradation (98%), however within a shorter time when compared to MIL101(Cr). Catalysts followed the pseudo first-order kinetic model with ZnO-MIL101@220 °C having a rate constant of 2.83 × 10−2 min−1. This is 2.3× and 1.1× higher than ZnO and the respective MIL101(Cr), correspondingly. Scavenging tests reveal that the hydroxyl radical (•OH) is the primary reactive species for PHE degradation. A degradation mechanism is proposed based on this finding.