Effect of environmental factors on the photocatalytic degradation behavior of tetracycline in water
To explore the degradation pattern of tetracycline(TC)in actual water,ZnO was used as a photocatalyst to investigate the effects of reaction time,pH,humic acid(HA)concentration and tetracycline concentration on the photocatalytic degradation process under complex natural environmental conditions(aeration,heavy metals and light).The results showed that all three environmental conditions promoted the degradation of tetracycline.The large amount of dissolved oxygen under aeration would collaboratively promote the generation of superoxide radicals and hydroxyl radicals with the catalyst,enabling TC to reach 99%photocatalytic degradation efficiency.The addition of the heavy metal Cu(Ⅱ)caused the formation of TC-Cu(Ⅱ)-ZnO composite in solution,which significantly improved the degradation efficiency of TC by ZnO,reaching 89%degradation efficiency at 30min.Natural light possessed a full spectrum and exhibited stronger TC degradation compared to visible light,with a TC degradation rate of 86%,which was 14%higher than that achieved under the visible light.The synergistic effect of the three factors could effectively reduce the degradation time of TC,reaching degradation equilibrium at 75min with 99%degradation efficiency.The photocatalytic activity in different environmental states was compared by kinetic analysis and the results were aeration>heavy metals>light.