the resin was converted to the hydrogen.
2.1.2. Metal complexes
Synthetic bioleaching solutions were prepared using
analytical-grade reagents; Ni(NO3)2·6H2O and Co(NO3)2·
6H2O Sigma–Aldrich metal salts and citric, dl-malic and
lactic organic acids (Bonnet, Australia). Metal solutions with
concentrations from 15 to 2000 mg/L were prepared using 0.01
and 0.1M of organic acid solutions. These concentrations are
typical of the acids produced by fungi microorganisms [1,18].
Acid concentrations of 0.01 and 0.1M typically generated
solution pH of 2.2 and 1.8 in citric acid, 2.8 and 2.0 in malic
and 2.6 and 1.9 in lactic acids.