%A . KARMANTO %J Kaunia Jurnal Sains dan Teknologi %T Sintesis dan Karakterisasi Material Lempung Magnetik (Mg/Alhydrotalcite-Magnetit) %X The study of onmagnetic clay’s synthesis and characterization, Mg/Al hydrotalcite-magnetite, in precipitation method has been done. This study aims to determine the material magnetism and stability characteristics of Mg/Al hydrotalcite-magnetite to the changing in pH of medium. Synthesis of Mg/Al hydrotalcite - magnetite conducted in two phases namely the formation of magnetite phase and magnetic synthetic clay phase formation. At the stage of the magnetite phaseformation, magnetite with a molar ratio of Fe(III) : Fe(II) = 1:1 and 2:1 , synthesized by coprecipitation method using NaOH solution at pH13. Then part of the magnetite material obtained, were characterized using X - Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR). At the stage of the Mg/Al hydrotalcite - magnetite formation, magnetite respectively were synthesized with the molar ratio of Fe(III) : Fe (II) = 1:1 and 2:1, further be precipitated with a solution of magnesium nitrate and aluminum nitrate in molar ratio Mg:Al = 2:1. In this stage the pH of medium been maintained at range of 10-13, and then carried out the hydrothermal treatment at a temperature of 110 ° C for 5 hours. After the precipitate is separated by using a centrifuge, the feculence bedried and the material obtained were characterized using XRD and FTIR. The results show synthesized magnetite with amolarratio of Fe(III): Fe(II) =1:1 had diffractogram, and IR spectra better than synthesized magnetite with the molar ratio of Fe(III): Fe(II) = 2 : 1. The same results were also obtained in the synthesis of Mg/Al hydrotalcite-magnetite, where the Mg/Al hydrotalcite-magnetite synthesized from magnetite with a molarratio ofFe(III): Fe(II) =1:1is betterthan theMg/Alhydrotalcite-magnetite synthesizedfrommagnetitewith amolarratio ofFe(III): Fe(II) =1:1. Magentism test for Mg/Alhydrotalcite-magnetite material shown that this material has capability for interacting with external magnetic field.Result ofthe Mg/Alhydrotalcite-magnetite’sstabilitytestatpHrange2-14, shownthat theMg/Alhydrotalcite-magnetite is relativelystableat pHabove4andrelativelylessstableat pHbelow 4. %N 2 %K magnetite,Mg/Alhydrotalcite-magnetite %P 34-46 %V Vol.IX %D 2013 %I FAK. SAINTEK UIN SUNAN KALIJAGA %R 2301-8550 %L digilib18657