抄録
Layered double hydroxides (LDHs) are the well known class of lamellar compounds with anion exchange ability. In this study, Mg-Al-CI LDH was complexed to siliceous porous carriers in order to develop a practical adsorbent for anionic dyes. First, the carrier granule such as synthetic silica gel or natural cristobalite rock was added into the mixed aqueous solution of MgCl2 and AlCl3 to impregnate both metal ions in the pores of the carrier and then the resulting suspension was poured slowly to a NaOH solution at 60°C and pH 10 with agitation. A large portion of the LDH, Mg1-xAlx (OH) 2Clx·yH2O (x=0.21-0.22, y=0.59-0.78), was found to form in the pores of the carrier. From the anion exchange experiment using Orange II, the composite materials exhibited the high exchange ability and theability based on LDH unit weight became as follows: LDH/ silica gel (pore size 70Å)>LDH/cristobalite rock (pore size 198Å)>LDH. Thus the more LDH was dispersed finely to the carrier, the more exchange ability for anionic dye was enhanced.
