Synthesis Of Hydrotalcite-like Compounds And Research On Its Properties Of Adsorption Of Fluorides

Mg(NO₃)₂ ? 6H₂O, A1(NO₃)₃ ? 9H₂O, Fe(NO₃)₃ ? 9H₂O, NaOH and Na₂CO₃ being raw material, a sorbent Nano-Mg/Al/Fe Hydrotalcite-like Compounds(HTLCs) were prepared by co-precipitation method and Mg/Al/Fe mixed oxides(HTLCs-500) were obtained by calcination of corresponding HTLCs.Both HTLCs was characterized by all kinds of chemical analysis method and the modem techniques. The structure and morphology of HTLCs was studied by X-ray diffraction(XRD), infrared spectroscopy measurements, TG-DTA and BET surface area. The ability of HTLCs to remove fluoride from aqueous solution was investigated.All the adsorption experiments were carried out as a function time, pH, initial concentration of adsorbent, adsorbent dose etc. It was found that: the HTLCs sample prepared is hexagonal multilayer in structure, which is similar with the structure of hydrotalcite crystal. The HTLCs sample prepared contains a lot of OH^- on the surface and there are CO₃^2- anion at the interlayer of it. HTLCs appeared little adsorption ability for fluoride, while the adsorption ability of the calcined products (HTLCs-500) were found to increase. By studying a function of time, pH, initial concentration of adsorbate, HTLCs-500 adsorption dose etc. It was found that the maximum adsorption of HTLCs-500 for fluoride takes place within 2.5 h at pH 6.0 and the adsorption data fitted well into the Langmuir equation. The adsorption mechanism involves the adsorption of fluoride ions on HTLCs-500 occurs by the reconstruction of the layered structure. The HTLCs-500 sample prepared has three specialties as a new sorbent for removing fluoride: obvious removal of fluoride ions attained at low dose with high adsorption rate. solid and liquid dividing easily and no secondary pollution produced. convenient and fast to operate, no need for complex equipment.