Removal of tetracycline residue from pharmaceutical wastewater by using 3D composite film

The widely utilization of pharmaceutical and personal care products in the pharmaceutical therapies and agricultural husbandry has led to the worldwide pollution in the environment. However, effective purification of water contaminated by tetracycline (TC) remains a great challenge. Here, 2-dimensional (2D) zeolitic imidazolate framework-L (ZIF-L) nanoflakes with a leaf-like morphology, which could selectively adsorb TC, was successfully synthesized in aqueous media at room temperature. The removal efficiency of ZIF-L powder for TC from pharmaceutical wastewaters was greatly influenced by the solution pH, contact time, temperature and solution concentration. In order to solve these problems, ZIF-L nanoflakes were fabricated on the surface of polyethyleneimine (PEI) modified nylon microporous filter to form a 3-dimensional (3D) composite film by vacuum filtration. The result showed that this novel material could effectively remove about 99.0% of TC from pharmaceutical wastewater. Furthermore, ZIF-L film not only excluded the effects of solution pH, contact time, temperature and solution concentration on the adsorption capacity for TC, but also had a high flux (1639 L m−2 h−1 bar−1), making it suitable for a large-scale application. The probable adsorption mechanism was investigated and suggested.