Mg/Al LAYERED DOUBLE HYDROXIDE ANIONIC CLAY AS A POTENTIAL MATERIAL FOR THE REMEDIATION OF ACID MINE LEACHATE

Sri Juari Santosa, Eko Sri Kunarti, Karmanto Karmanto, Nur Aini Iksan

Abstract


Mg/Al hydrotalcite (Mg/Al HT) with interlayer anionic species of nitrate (NO3-) and carbonate (CO32-) has been synthesized and then applied to neutralize H+ and remove sulfate (SO4 2-), fulvic acid (FA) and humic acid (HA) which is commonly present in acid mine leachate. As a layered double hydroxide anionic clay, Mg/Al HT has high affinity towards SO4
2- and deprotonated FA and HA. Sulfate and deprotonated FA and HA are removed by Mg/Al HT through anion exchange with interlayer NO3 - and CO3 2- and the exchanged CO3 2- then consumes H+ to form bicarbonate (HCO3-) and hence decreases the sample acidity. At optimum removal condition (pH 5 for SO4 2- and pH 9 for FA and HA), the removal of SO4 2-, FA and HA followed the second order kinetic model and the maximum amount of those species removed by Mg/Al HT was 12.38, 7.83 and 1.18 x 10-4 mol/g or equivalent to 264, 183 and 70 mg/g, respectively. This performance of Mg/Al HT in interchanging SO4
2-, FA and HA with the interlayer CO3 2- gave a buffering effect to pH range of about 5.0 to 8.7.

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