| Antibiotics have a wide range of applications in disease treatment,animal husbandry,aquaculture,etc.The concentration of antibiotics in the environment,through the spread of the food chain,and finally into people's bodies,will threaten people's health.Tetracycline is a type of antibiotic that is used as a target for contamination to study the removal of tetracycline.In recent years,nano-zero-valent iron plays an important role in environmental management.It has the characteristics of large specific surface area and strong reactivity,but nano-zero-valent iron is prone to oxidation and agglomeration,and its stability is poor.Therefore,the modification of nano-zero-valent iron is a hot topic of research today.In this paper,three kinds of clays,such as attapulgite,halloysite and bentonite,were selected as carriers to achieve the function of dispersing nZVI,preventing its agglomeration,and using transition metal nickel as another metal to introduce,increasing the specific surface area of nZVI and enhancing its reaction.The activity was thus prepared to prepare a clay mineral-loaded nano-iron-nickel bimetal composite material(APT-Fe/Ni composite,HNTs-Fe/Ni composite,BT-Fe/Ni composite).The composites was characterized and analyzed,and the effect of the composite on the removal of tetracycline under different conditions was studied.Finally,the effects of composite materials on the removal of tetracycline in tap water,well water and Yellow River water and the recycling performance were investigated.The results show:(1)Transmission electron microscopy(TEM),X-ray diffraction(XRD),specific surface area(BET)and X-ray photoelectron spectroscopy(XPS)of APT-Fe/Ni,HNTs-Fe/Ni,BT-Fe/Ni composites Analysis characterization found that nano-iron-nickel particles had very good dispersibility on APT-Fe/Ni composites and BT-Fe/Ni composites,and nano-iron-nickel particles on HNTs-Fe/Ni composites had the phenomenon of partial agglomeration;the specific surface area of the three composite materials were 93.01 m~2/g,59.65 m~2/g,48.39 m~2/g;three composite materials,containing zero-valent iron and zero-valent nickel and its oxides.According to the FTIR spectrum analysis of the three composite materials before and after removal of tetracycline,it can be obtained that the tetracycline was degraded into small molecular substances such as C=O and C=C,which were adsorbed on clay minerals,and the nano-zero-valent iron utilizes its own strong reducibility to degrade tetracycline;The formation of galvanic cells by iron and nickel and the easy combination of H~+and nickel prevent the oxidation of nano-iron,increase the surface energy and promote the removal of tetracycline.At the same time,the large specific surface area and certain pore size structure of the three clays are Tetracycline also has a certain adsorption reaction.(2)Removal of tetracycline by APT-Fe/Ni,HNTs-Fe/Ni,BT-Fe/Ni under different conditions:optimal pH=3,tetracycline removal was 170.90 mg/g,The reaction equilibrium time was 146.90 mg/g and 199.10 mg/g,and the reaction equilibrium time was 80 min,60 min and 120 min.With the increase of tetracycline concentration,the removal amount increased gradually.(3)The removal of tetracycline by APT-Fe/Ni,HNTs-Fe/Ni and BT-Fe/Ni composites conformed to the adsorption isotherm and kinetic model,and the reaction process included chemical and physical adsorption.(4)In the removal of tetracycline in tap water,well water and Yellow River water by BT-Fe/Ni composites,the removal rate of tetracycline in the Yellow River was the largest,and the composite had a wide range of pH for the removal of tetracycline in three kinds of waters.After the composite material was repeatedly used five times,the removal rate of tetracycline was 56.35%. |
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