Preparation Of Amorphous Aluminum-La Nathanum Hydroxides And Its Adsorption Properties Of Fluoride Ions

Fluorine is an essential element for the human body,but excessively high fluoride ion concentration in water can also cause harm to human health.In this paper,the metal-based adsorbent is used as the research object.The nano-aluminum-lanthanum hydroxide(HAL)adsorbent was prepared by co-precipitation method using aluminum chloride hexahydrate and lanthanum chloride heptahydrate as materials.The millimeter-grade aluminum-lanthanum hydroxide gel ball(CS-HAL)adsorbent was prepared under the load of chitosan,and its microstructure characterization and experimental study on adsorption performance were carried out.(1)The aluminum-lanthanum hydroxide adsorbent(HAL)was prepared by co-precipitation method.XRD,TEM and BET characterization found that the adsorbent HAL is random nanoparticles,and it has an amorphous structure and has a large specific surface area,which can provide abundant active sites for fluoride ions.The results of FTIR and Zeta potential analysis showed that the adsorption mechanism of fluoride ion at p H<7.5 is synergy between ion exchange and electrostatic attraction,and at p H>7.5,it is ion exchange.The adsorbent HAL reached adsorption equilibrium at 4 h,and the maximum adsorption capacity was 127.4 mg/g.(2)The millimeter-grade aluminum-lanthanum hydroxide gel ball(CS-HAL)were prepared and characterized by the embedding method.Characterization by XRD and SEM showed that the CS-HAL had an amorphous structure,the surface was loaded with irregular HAL particles,and the chitosan coating the surface was continuous and uniform with pores.The experimental results showed that the maximum adsorption capacity of the adsorbent CS-HAL reaches 35.6 mg/g,and the chitosan in the system only has the effect of loading the adsorbent HAL,and does not participate in the adsorption process.After 4 experimental studies on the stability of the cycle,the adsorption capacity decreased only by 14.3%.