RÉSUMÉ
Spent adsorbents for recycling as catalysts have drawn considerable attention due to their environmentally benign chemistry properties. However, traditional thermocatalytic strategies limit their applications. Here, we developed an enhanced photocatalytic strategy to expand the range of their applications. A magnetic chitosan/ZrO2 composites (MZT) for V(V) adsorption, which were prepared using chitosan, ZrO2 and Fe3O4 by one-pot synthesis. The spent MZT as a catalyst was used to synthesize 2-phenylbenzimidazole, yielding up to 89.7%. It also was implemented to photocatalysis reactions for recycle. The discolored rates of rhodamine B (RhB) were 72.3% and 97.4% by new and spent MZT, respectively. The new and spent MZT showed the forbidden bands were 251 nm and 561 nm, respectively. The result displayed spent MZT red shifted to the cyan light region. The mechanism of catalysis also has been studied in detail.