Abstract
Attapulgite calcined at 973.15K was characterized and utilized as an adsorbent for the removal of heavy
metals and neutralization of acid mine drainage (AMD) from a gold mine. Batch adsorption experiments were carried
out using a thermostatic shaker. Activated attapulgite showed that it can neutralize AMD as it raised the pH from 2.6
to 7.3 after a residence time of 2 h. Metal ion removal after 2 h was 100% for Cu (II), 99.46% for Fe (II), 96.20% for Co
(II), 86.92% for Ni (II) and 71.52% for Mn (II) using a 2.5% w/v activated attapulgite loading. The adsorption best fit
the Langmuir isotherm; however, Cu (II), Co (II), and Fe (II) data fit the Freundlich isotherm as well. Calcination at
973.15 K resulted in the reduction of the equilibrium residence time from 4 to 2 h, solid loading reduction from 10 to
2.5% m/v and an increase in maximum adsorption capacity compared with unactivated attapulgite.