Fast And Highly Efficient Removal Of Fluoride In Drinking Water Using Chitosan-Ca Complex

Fluorine is one of the essential trace elements in human body. We ingest through drinkingwater. But long-term excessive ingest fluorine will cause varying degrees of harm to human bodyhealth. Such as dental fluorosis, skeletal fluorosis, and even the central nervous system diseases.Since the70's of last century, the control of fluorine pollution in water has been an important issuein the field of environmental protection and health at home and abroad. Adsorption as a kind ofsimple and highly effective water treatment method, is widely used in the study of the problem ofenvironmental pollution control. Chitosan molecules contains a lot of activity of amino andhydroxyl groups. It is a natural macromolecular material with high adsorption performance. Butchitosan only soluble in acid solution and have a weak adsorption ability of alkaline resistance,these reasons restrict its application range. At present, many research to modified chitosan intoadsorption, greatly improve its adsorption performance.In this study, we choose CaCl2and KH2PO4to modified chitosan. Made the adsorbent intosmall balls, made the fluorine ion in drinking water as the main adsorbate. We study (1) Theinfluence factors of adsorption:preparation conditions, adsorption time, the pH of solution, initialconcentration of adsorbate, coexisting ions.(2)Study of adsorption kinetics and thermodynamics,get the corresponding adsorption kinetics and thermodynamics model and related parameters.(3)Characterization of modified chitosan and mechanism research.(4) The practical application ofmodified chitosan.(5)Desorption experiments. The experimental results show that(1)Add1.2g CaCl2,0.2g KH2PO4,2g chitosan into acetic acid solution get the best adsorption efficiency;Adsorption reaction reach to equilibrium after4hours; Chitosan-Ca have a wide range of pH;Cation have little impact on modified chitosan adsorption of fluoride, The different impact ofanion: CO2——3—2———3> HCO3> PO4> SO4> Cl—> NO3> NO2.(2)The pseudo-second-orderkinetic equation and Langmuir isotherm equation could suitably characterize the adsorptionbehavior of flouride by modified chitosan.(3) Through XAFS, FESEM, TEM, XRD, FTIR, putforward the possible adsorption mechanism.(4) To deal with initial concentration of10mg/L(fluorine ion) of well water, river water, tap water fluoride,its desorption efficiency is morethan90%, the concentration of fluorine ion remaining is below1.0mg/L.(5)After desorption, theadsorption efficiency could reach73.8%.