The synthesis of the CO3/Mg-Fe layered double hydroxide (LDH) by a standard coprecipitation method has been investigated together with its antacid property. The LDH crystallinity of the solid product was influenced by the synthesized pH, Fe/(Mg+ Fe) mixed molar ratio and aging time. The solid products have the carbonated LDH structure with the basal spacing, d003, of 7.8Å, in particular the well crystallized CO3/Mg-Fe LDH was obtained at pH 10, Fe/(Mg+Fe)=0.25 and aging time 5 hours. From the results of XRD and TG-DTA, it was found that lattice constants a and c of the CO3/Mg-Fe LDH obtained at the Fe/(Mg+Fe) mixed molar ratio of 0.17-0.25 range ageered with the Vegard rule, and the temperatures of elimination of interlayer water, dehydration of hydroxide basal layer and decarboxylation of guest anion were shifted by the amount of substituted Fe3+ ion for the LDH basal layer. In the durability experiments of the CO3/Mg-Fe LDH as antacid, the time effecting antacid property for 65-95 min was observed in the CO3/Mg-Fe LDH obtained at the Fe/(Mg+Fe) mixed molar ratio of 0.17-0.25 range. This feature of the CO3/Mg-Fe LDH indicates that it can be used as for the substitute of the CO3/Mg-Al LDH as antacid.
