▎ 摘　　要

This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO2 loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO2), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV-vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 degrees C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5 alpha were also assayed. After 180 min photocatalytic treatment, OTC solution treated by GTZ (1:8:1) showed insignificant biotoxicity to receptor DH5 alpha cells. Furthermore, EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system. The results showed that the holes are the main oxidation species in the photocatalytic process. (C) 2015 Published by Elsevier B.V.