Adsorption Of Pb²⁺ And Cd²⁺ In Water By Mango Snail Shell Loaded With Nanoscale Zero-valent Iron

Shells are a kind of renewable resources with abundant yield.At present,except for a few kinds of shells,which are used in a limited number of ways,most shell resources are directly discarded,which wastes resources and pollutes the environment.The nano-zero-valent iron adsorbent has been widely concerned with its high activity,strong adsorption and environmental friendliness,but the limitation of nano-zero-valent iron easy agglomeration limits its large-scale application.Therefore,the carrier can be used to load the nano zero-valent iron to prevent its agglomeration.In this paper,the use of mango snail shell powder for the loading of nano-zero-valent iron adsorbent not only finds a new way for the utilization of shell resources,but also excavates a new kind of carrier for preventing the agglomeration of nano-zero-valent iron.In this paper,the four kinds of shells commonly used in Hainan were pretreated by pulverization and calcination.The shellfish powder with the best adsorption performance was screened by studying the adsorption of Pb2+ and Cd2+ by different kinds of shell powder after calcination.Further optimization.The optimized zero-valent iron was loaded with the optimized shell powder,and the adsorption performance of the adsorbent on Pb2+and Cd2+ was investigated.The adsorption,Pb2+ and Cd2+ adsorption factors were discussed.influences.The shell powders before and after calcination and nano-zero-valent iron were characterized by infrared spectroscopy,scanning electron microscopy,TGA and XRD.Through the experimental experiment,the following conclusions were obtained:The IR/SEM characterization results show that the main component of the shell powder after calcination at 500? is CaCO3,which has a porous structure,the specific surface area is significantly increased,and the adsorption performance is enhanced.The adsorbent dosage,adsorption time,temperature and other factors have significant effects on the adsorption of Pb2+ and Cd2+ by shell powder.Under the factors of optimization,the four shell powders showed strong adsorption to Pb2+ and Cd2+,among which mango snail shells.The adsorption effect of the powder on the two ions is significantly better than the other three.By optimizing the preparation process of mango snail shell powder,the optimal conditions for preparing shell powder adsorbent were as follows:the particle size was over 140 mesh,the activation temperature was 450?,and the activation time was 60 min.The optimized mango snail shell powder was characterized by TGA/XRD/SEM.The results showed that the mango snail shell powder after calcination formed obvious porous shape,the specific surface area increased significantly,and the adsorption performance was significantly improved.The calcined mango snail shell powder has stable properties and good adsorption performance,so it can be directly applied to adsorption practice,and can also be used as a load base in the research of other types of adsorbents.The mango snail shell powder was used as raw material to prepare nano-zero-valent iron adsorbent loaded with mango snail shell powder.The effects of adsorbent dosage,pH and temperature on the adsorption effect were discussed.The adsorption of nano-zero-valent iron adsorbent on mango snail shell powder was investigated by three factors.The effects of Pb2+ and Cd2+ were significantly affected.By fitting the adsorption isotherms,it was found that the fitting effect on the Freundlich model was the best,and the adsorption of Pb2+ and Cd2+ was preferential adsorption.The nano-zero-valent iron loaded on mango snail shell powder was characterized by FT-IR,SEM and XRD.The results showed that Feo was abundantly present on the shell powder surface after loading,and the surface particles of the adsorbent increased significantly,and the nano-zero was not loaded.Compared with the scanning electron micrograph of the mango snail shell powder of the valence iron,the pore diameter is significantly smaller,which indicates that the ferrous ion is reduced and adhered to the surface of the shell powder,and the load is successful;after the mango snail shell powder is loaded with the nano zero-valent iron,there is Significant Fe characteristic peaks,in addition,retain a small number of aragonite and calcite-type calcium carbonate peaks.In addition,some of the zero-valent iron is oxidized during the preparation or transfer process.