A Study On Adsorption Properties Of Cd²⁺ And Pb²⁺ On Layered Double Hydroxide?LDH? Intercalated With EGTA And SDS

In this paper, for the target of improving the adsorption capacity for metal ions in aqueous solution,we designed the synthesis process of different anions intercalation hy drotalcite, chose reasonable precursor synthesis methods, suitable intercalateel anions. and suitable operation conditions, which in order to prepare good crystallinity hydrotal cite(Layered Double Hydroxides, referred to as LDHs). We synthesized the precursor zin c and aluminum nitrate hydrotalcite by the coprecipitation method, and then intercalate d ethylene glycol bis(2-aminoethyl ether) tetraacetic acid(EGTA) and sodium dodecyl s ulfate(SDS) by ion exchange method.The physicochemical properties of the products, ZnAl-NO3-LDH, ZnAl-EGTA-LD--H and ZnAl-SDS-LDH,were characterized by the methods of X-ray photoelectron sp--ectroscopy(XPS), the fourier transform infrared spectrometer(FT-IR), X-ray powder dif fraction(XRD), N2 physical adsorption instrument,scanning electron microscopy(SEM) a-nd so on. The results showed that the intercalated hydrotalcite maintained the original crystal morphology well, and have a high degree of anion exchange. The interlayer di stance of the intercalation hydrotalcite was not only affected by the size of interlayer organic anions, but also depended on the arrangement of the organic anions in the int-erlayer. The amount of the interlayer water, the composition of the layer plate elemen ts, the degree of ion exchange of organic anions would also influence the arrangemen t of interlayer. The structure and the amount of the interlayer organic anions would le ad to a regular variation of the thermal stability of the pillared hydrotalcites.The products, Zn Al-NO3-LDH, ZnAl-EGTA-LDH and ZnAl-SDS-LDH were used a s adsorbent, respectively.Then the Cd2+ and Pb2+ in aqueous solution were used as adsor bate. We studied the effects of some parameters on adsorption process, such as the pH value, time, temperature, initial concentration of metal ions and amount of adsorbent. Th-e amount of Cd2+ and Pb2+ absorbed were measured by atomicabsorption spectrophoto meter. In the same conditions,the adsorption capacity of ZnAl-NO3-LDH, ZnAl-EGTALDH and ZnAl-SDS-LDH were also studied and compared. The results showed that t he adsorption capacity was ZnAl-EGTA-LDH>ZnAl-SDS-LDH>ZnAl-NO3-LDH.