Photocatalytic MIL101(Fe)/ZnO chitosan composites for adsorptive removal of tetracycline antibiotics from the aqueous stream

Abstract

Antibiotics are widely used to treat bacterial infections in humans and animals. Among different classes of antibiotics, tetracycline (TC) is the most used, and its elimination from the environment has become a serious concern. The present study focused on the facile synthesis of zinc oxide (ZnO) nanoflowers, Matériaux de l' Institut Lavoisier 101 (MIL-101(Fe)) and MIL101(Fe)/ZnO chitosan composite beads for the adsorptive removal and photocatalytic degradation of TC. The effect of various operational parameters such as adsorbent dosage, TC concentration, pH and time was investigated. The MIL101(Fe)/ZnO chitosan composite beads were characterized by XRD, TGA, SEM, BET surface area and FT-IR. The MIL101(Fe)/ZnO chitosan composite beads showed high thermal stability up to 250 °C and the highest adsorption capacity of 31.12 mg g−1. The PSO adsorption kinetics and Langmuir adsorption isotherm were found the best fit. The adsorption of TC on the MIL101(Fe)/ZnO chitosan composites was attributed to the π -π interaction between the aromatic rings of TC and the adsorbent. The adsorption of the TC was confirmed using the SEM and FT-IR; the TC was visible on the bead's surface that showed the affinity of the synthesized beads towards the adsorption of the TC. The beads were regenerated with high efficiency in the presence of sunlight. The photo-excitation was due to MIL101(Fe) and ZnO, which created the electrons (e−) and holes (h+) in the structure. The beads showed a removal efficiency of more than 90% up to 5 cycles. Therefore, the MIL101(Fe)/ZnO chitosan composite beads can be used and reused for a long period.