Adsorption and photocatalytic degradation mechanism of magnetic graphene oxide/ZnO nanocomposites for tetracycline contaminants

The removal of tetracycline (TC) by novel magnetic graphene oxide/ZnO nanocomposites (MZ) was explored. In order to study the feasibility of MZ as an adsorbent and photocatalyst to remove tetracycline, a series of experiments were carried out. Fortunately, MZ shows outstanding adsorption capacity for TC and can be easily separated from water. The pseudo-second-order kinetics model can explain the adsorption process of TC well, and the maximum adsorption capacity is 1590.28 mg g(-1). Analyzing various results, it was found that the adsorption mechanism can be explained by electrostatic attraction, pi-pi interaction, hydrogen bonding, cation exchange, and complexation. In the experiments of photocatalytic degradation of TC, graphene oxide acts as the framework and promotes the electron transfer, ZnO acts as an effective photocatalyst. In addition, MZ remained relatively high levels of removal after four cycles. The information provided by these results confirms the great potential of MZ as a highly efficient adsorbent and photocatalyst in removing tetracycline pollutants in water.