2.4. Biosorption of heavy metal ions
Biosorption of Cd (II), Cu (II), Co (II), Ni (II) and Pb (II) from synthetic
wastewaters containing single and mixed metal ions were
investigated in batch experiments. Stock metal solutions at various
concentrations were prepared by dissolving lead nitrate, copper
nitrate trihydrate, cadmium (II) nitrate hexahydrate, cobalt (II)
nitrate hexahydrate, nickel nitrate hexahydrate and zinc nitrate
tetrahydrate and all were analytical grade reagents. A solution
of known metal ion concentration was prepared and a known
quantity of adsorbent (MOSB or ligand) was added. The mixtures
were shaken with a flask shaker (Stuart Scientific unless otherwise
stated) and the concentration of the unadsorbed metal ions in
solutions were determined after separation of the sorbent by centrifugation
and filtration using Whatman paper No. 1 filter papers.
The effects of contact time, initial metal ion concentration and pH
were studied. The pH was adjusted using either 0.1 M NaOH or
0.1 MHCl.Analysis andinstrumentationformetaluptake tests were
done using FAAS with air/acetylene. The amount of metal sorbed
by biomass or ligand (expressed as % bound or % removal) was calculated
from the difference between the initial metal quantity (Co)
and the metal content of the supernatant (Cf) using the following
equation:
% Removal = Co − Cf
Co
× 100