Photocatalytic Degradation Of Tetracycline In Wastewater By Nano-Zn/Fe Doped With Frustule Shell

Antibiotic wastewater has high chroma,high biological toxicity characteristics,and it's difficult to biodegrade.So its treatment has always been a major problem in the field of wastewater treatment.Therefore,finding simple,efficient,low-cost and environmentally friendly treatment technologies is the key to ensuring the safe discharge of antibiotic wastewater.Photocatalytic oxidation technology is a green technology with important application prospects in the environmental field.Due to its high efficiency,good stability and no secondary pollution to the environment,it has become one of the main treatment technologies for antibiotic degradation.Among that,the preparation and modification of photocatalysts is the focus of research.In this paper,a nano-zinc oxide?ZnO?photocatalyst was prepared,and its structure,morphology,crystal form were infered by a series of characterization methods.When the concentration of TC-HCl is 10 mg/L,under the irradiation of a high-pressure mercury lamp,the photocatalytic activity of nano-ZnO was tested by degrading tetracycline hydrochloride?TC-HCl?.The results show that,nano-ZnO is as clusters of flowers.Under the optimal conditions,the degradation rate of TC-HCl can reach 96.4%.However,the stability of nano-ZnO is poor.After five cycles,the degradation rate of TC-HCl is reduced to 59.5%.The results of free radical shielding experiments show that the active free radicals that affect the degradation of TC-HCl are mainly O₂^-and h⁺.The nano-ZnO was doped by using the porous nanostructure of the siliceous shell to obtain a Shell-ZnO composite material,which improves the photocatalytic activity and stability of the nano-ZnO,and used it for photocatalytic degradation of TC-HCl.The results show that,When the concentration of TC-HCl is 10 mg/L,the degradation rate of Shell-ZnO composites to TC-HCl was 94.5%,and the stability of the composite was significantly improved.After five cycles of use,the degradation rate of TC-HCl was83.5%.The results of free radical shielding experiments show that the free radical activity of TC-HCl photocatalyzed by Shell-ZnO is h⁺>.O₂^->.OH.The unique magnetic properties of Fe₃O₄ are used to composite with Shell-ZnO to obtain a siliceous shell-doped zinc/iron nanooxide?Shell-Fe/ZnO?composite material,which is beneficial for its recycling after water treatment.At the same time,the photocatalytic activity of the composite was improved by doping Fe₃O₄.When the concentration of TC-HCl is 10 mg/L,the degradation rate of TC-HCl reached 96.56%.When the catalyst was used five times,the degradation rate could still reach 90.4%.The results of free radical shielding experiments show that the active free radicals that affect the photocatalytic efficiency are mainly.O₂^-and h⁺.