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The feasibility of using vibratory ball milled South African bentonite clay for neutralisation and attenuation of inorganic
contaminants from acidic and metalliferous mine effluents has been evaluated. Treatment of acid mine drainage (AMD)
with bentonite clay was done using batch laboratory assays. Parameters optimised included contact time, adsorbent dosage
and adsorbate concentration. Ball milled bentonite clay was mixed with simulated AMD at specific solid: liquid (S/L) ratios
and equilibrated on a table shaker. Contact of AMD with bentonite clay led to an increase in pH and a significant reduction in
concentrations of metal species. At constant agitation time of 30 min, the pH increased with the increase in dosage of bentonite
clay. Removal of Mn2+, Al3+, and Fe3+ was greatest after 30 min of agitation. The adsorption affinity obeyed the sequence:
2- (221.8 mg g-1) > Mn (30.7 mg g-1) > Al (30.5 mg g-1) > Fe (30.2 mg g-1). The pH of reacted AMD ranged from ≈3 to 6.
Bentonite clay showed high adsorption capacities for Al and Fe at concentration < 500 mg/L, while the capacity for Mn was
lower. Adsorption capacity for sulphate was >50%. Adsorption kinetics revealed that the suitable kinetic model describing data
was pseudo-second-order hence confirming chemisorption. Adsorption isotherms indicated that removal of metals fitted the
Langmuir adsorption isotherm for Fe and sulphate and the Freundlich adsorption isotherm for Al and Mn, respectively. Ballmilled
bentonite clay showed an excellent capacity in neutralising acidity and lowering the levels of inorganic contaminants in
acidic mine effluents.