Recycling of hyper-accumulator: Synthesis of ZnO nanoparticles and photocatalytic degradation for dichlorophenol

• ZnO nanoparticles were prepared using zinc hyper-accumulator plants.
• The synthetized ZnO nanoparticles showed good photodegradation properties for 2-CP.
• This method provides a new insight into the reuse and recycling of hyper-accumulator plants.

In this work, the zinc oxide nanoparticles (ZnO NPs) were synthesized using zinc chlorophyllin prepared from zinc hyper-accumulator (Sedum alfredii Hance) plants. The chlorophyllin was extracted from the shoot of Sedum alfredii plants with ethanol. In addition, the Zn in them was also extracted and formed to zinc sulfate (ZnSO4) by sulfuric acid. The chlorophyllin reacted with ZnSO4 to form zinc chlorophyllin. Afterward, ZnO NPs were synthesized using zinc chlorophyllin and NaOH. Characterization results revealed that the synthetized ZnO NPs were pure, dispersed, with length around 100 nm, and the most morphology of single particle was column in shape. In addition, the photodegradation properties of synthetized ZnO NPs for 2-chlorophenol were also investigated. The photolysis efficiency of 2-CP was only 5.47% with simulated sunlight irradiation for 120 min. Although 17.66% 2-CP was adsorbed by ZnO NPs in dark, the degradation efficiency of 2-CP achieved to 96.93% with the combination of ZnO NPs and simulated sunlight irradiation for 120 min. The photooxidation of 2-chlorophenol was mainly initiated by O2− which generated from the combination with the irradiation and ZnO NPs. However, the synthetized ZnO NPs were not suitable for removal 2-chlorophenol in water owing to the residual toxicity. These findings also constitute a new insight into the reuse and recycling of hyper-accumulator plants.