Preparation of organic acid anion-modified magnesium hydroxides by coprecipitation: A novel material for the uptake of heavy metal ions from aqueous solutions

New layered magnesium hydroxides whose brucite layers had been bridged with malate2− and tartrate2− were prepared by dropwise addition of Mg(NO3)2 to malate and tartrate solutions at a constant pH of 10.5. Malate2− and tartrate2− may have been also absorbed on the surfaces of hydroxides. In the case of using citrate solution, Mg(OH)2 absorbed with citrate3− was produced. These materials were found to take up Cu2+ rapidly from an aqueous solution at pH 5.0. Copper uptake by precipitates is attributed to the formation of chelate complexes of Cu2+ with citrate3−, malate2−, and tartrate2−.