Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

► The grafting of hydrogen phosphate intercalated Mg/Al-LDH has been studied. ► The basal spacing of crystalline LDH-HPO4 decreases in two stages with increasing temperature. ► The first decrease is due to loss of interlayer water, the second is attributed to phosphate grafting. ► The grafted interlayer phosphate becomes immobilized and cannot be removed by anion-exchange.