Preparation Of Modified Attapulgite And The Study For The Removal Of Tetracycline In Water Environment

Due to the large amount of antibiotics used in the Chinese pharmaceutical industry and the abuse of antibiotics in the aquaculture industry,the pollution of tetracycline antibiotics in China is becoming more and more serious.Only a small part of the used tetracycline is metabolized or absorbed in the body,and most of it is released in excreta in unchanged form,which causes water pollution,increases environmental ecological risks,and brings potential harm to human health.At present,two main methods of the removal of tetracycline(adsorption and biological method)have their limitations,so the removal effect is not ideal.Attapulgite is a layered,chain-shaped,magnesium-rich silicate clay mineral.The crystal particles of attapulgite are very small to only tens of nanometers,and attapulgite has nano-scale pores in the structure,which makes it have a large specific surface area.The special apparent structure and large specific surface area make attapulgite have strong adsorption performance.This article aimed to modify attapulgite.On the one hand,to improve its own adsorption performance through thermal modification;on the other hand,it was used as a carrier to combine with BiFeO3 and Fe3O4 to prepare composite catalytic materials.Scanning electron microscope,X-ray diffraction,X-ray photoelectron spectroscopy,Thermogravimetric analysis,Ultraviolet-Visible diffuse reflectance spectroscopy were used to characterize the materials before and after modification,and to explore the effect of modified materials on the removal of tetracycline in aqueous solution.The main research contents and results of this paper were as follows(1)The adsorption property of attapulgite(ATP)on tetracycline(TC)was improved by calcination method,and the mechanism of cyclic adsorption of attapulgite was systematically investigated by X-ray diffraction(XRD),Scanning electron microscope(SEM),Ultraviolet-visible diffuse reflectance spectroscopy(TGA)and CHNS elemental analysis.The results showed that the attapulgite modified by calcination improved the adsorption of tetracycline and the best modification effect at 400℃.At the same time,after repeated recycling,carbon content on attapulgite increased,but the adsorption rate of tetracycline remained more than 93%,which indicated that attapulgite had practical application value in wastewater treatment.(2)The morphology of bismuth ferrite was adjusted by hydrothermal method,and attapulgite(ATP)and bismuth ferrite(BiFeO3)were successfully combined to prepare an efficient composite photocatalyst ATP/BiFeO3.Scanning electron microscope(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Ultraviolet-Visible diffuse reflectance spectroscopy(UV-vis)were used to characterize the photocatalyst,and the photocatalytic degradation of tetracycline(TC)by ATP/BiFeO3 composite was studied,and the possible photocatalytic mechanism was proposed.The results show that the doping of ATP has an obvious effect on the removal of TC by ATP/BiFeO3.When ATP:BiFeO3=1:10 the highest removal rate of TC is 82.4%.The synergism of ATP and BiFeO3 enables that the composite material has significant activity for the photocatalytic degradation.of TC.(3)In order to obtain high-efficiency catalytic materials,in this study,iron oxide(Fe3O4)nanoparticles were supported on attapulgite(ATP)by co-precipitation method,and a heterogeneous Fenton-like catalyst ATP@Fe3O4 with both adsorption and catalytic properties was successfully prepared.Scanning electron microscope(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Magnetization curve(VSM)were used to characterize the composite materials,and their catalytic effects on the degradation of tetracycline(TC)by persulfate(PS)were studied.The results show that the ATP@Fe3O4 composite is a powerful catalyst for the activation of persulfate to generate sulfate radicals(SO4·-),and the ATP@Fe3O4/PS system shows a good ability to remove tetracycline in aqueous solution.When the PS concentration was 10 mM,the catalyst dosage was 1.5 g/L,and the pH of the tetracycline solution was 3.9,the effect of the ATP@Fe3O4/PS system for removing tetracycline was the best.