Study On Removal Of Fluoride From Antarctic Krill By The Magnetic Adsorption Material

Antarctic krill attracts widely attention due to its huge biomass and high protein content.However,the excessive fluoride content of Antarctic krill severely limits the exploration and utilization of this type of biological resources.In this study,a type of magnetic composites composed of Fe3O4,hydroxyapatite(HA)and chitosan(CS)was prepared by using chemical co-precipitation method.The magnetic adsorbent material was used to remove fluorine from aqueous solution and the Antarctic krill protein hydrolysates.The properties of the magnetic composites were characterized by using scanning electron microscope(SEM),x ray diffraction(XRD),infrared-ray(IR),thermogravimetric analysis and vibration saturates magnetometer(VSM).The SEM and TEM micrograph confirmed that Fe3O4 was coated with HA and CS;The XRD and IR spectra confirmed the presence of CS and HA in the magnetic HA/CS composites;The DT-TGA confirmed that the magnetic HA/CS was hybridized by CS and HA.VSM analysis determined that the saturated magnetization of the Fe3O4 and the magnetic HA/CS composited was 58.97emu/g and 20.73emu/g,respectively.Taken removal rate of F-in aqueous solution as an indicator,the effects of the contact time,pH,the dosage of the adsorbent,the initial concentration of F-,temperature and coexistence of anions and cations on the adsorption properties of the composites were studied.Results showed that the suitable condition for removal of F-from aqueous solution of the magnetic HA/CS were:contact time of 10 min,pH of 7.0,and adding amount of adsorbent of 0.25g.The presence of coexisting HCO3-had adverse effect on the sorption capacity of the composites.Results showed that the suitable condition for removal of F-from the Antarctic krill hydrolysate solution of the magnetic HA/CS was:pH of 7.0,temperature of 40 ?,and adding amount of adsorbent of 20mg.Under this condition,the removal rate of total fluoride,water soluble fluoride and acid soluble fluoride were 30%,93%and 42%,respectively.The magnetic HA/CS composite has good bio-compatibility,bio-degradability and good mechanical strength,and could be used as a type of environment-friendly composites for removal F-.