Abstract: In order to obtain Mg-Al hydrotalcite with gread dechlorination performance,the effect of alkali source on the structure and dechlorination performance of Mg-Al hydrotalcite was studied. In this paper,LDHs-A and LDHs-B were synthesized by hydrothermal synthesis method using urea and sodium hydroxide as base sources and metal nitrate salt solution as precursor,respectively. XRD,SEM,BET and FTIR tests were used to analyze the effects of different base sources on the microstructure of Mg-Al hydrotalcite. The dechlorination properties and mechanism of two kinds of hydrotalcite were compared by chloride ion adsorption experiment. The results show that LDHs-A and LDHs-B have XRD peaks similar to hydrotalcite structure,with lamellar structure,grain sizes of 1 000~ 2 000 nm and 200~ 400 nm,and specific surface areas of 40. 804 m2 / g and 62. 609 m2 / g,respectively. The saturated adsorption capacities were 45. 41 mg / g and 78. 69 mg / g,respectively. LDHs-A is magnesium and aluminum hydrotalcite by carbonate intercalation and LDHs-B is magnesium and aluminum hydrotalcite by nitrate intercalation. LDHs-A conforms to the quasi-first-order kinetic model and Langmuir adsorption isothermal model,and the dechlorination mechanism is mainly single-layer physical adsorption;LDHs-B conforms to the quasi-second-order kinetic model and Langmuir adsorption isothermal model,and the dechlorination mechanism is mainly single-layer chemisorption.

Key words: hydrotalcite-like,hydrothermal synthesis,chloride ion,adsorption material