A new approach to chemical modification protocols of Aspergillus niger and sorption of lead ion by fungal species
Omotayo Rafiu Awofolu*
Jonathan Okechukwu Okonkwo
Renate Roux-Van Der Merwe
Financial support: Fellowship awarded to Dr O.R. Awofolu by Tshwane University of Technology Pretoria, South Africa.
Keywords: Aspergillus niger, fungi species, lead ion, modification, sorption.
Biomasses of five fungi species (Aspergillus niger, Penicillium austurianum, Saccharomyces cerevisiae, Mucor arcindloides and Trichoderma reesi were evaluated for their uptake of lead ion from aqueous solution using batch systems. Both dead and live fungal biomasses were comparatively studied for their adsorption efficiencies. The effect of pH as one of the primary factors that influences sorption efficiency of metal ions in solution was also studied. Modification of the fungal biomass with the least sorption capacity was carried out using a four-step procedure. Three different modifying agents under the optimised experimental conditions were used. The percentage uptake of lead ion by fungi species ranged from: Aspergillus niger: 6.71-64.95% and 66.91-95.27%; Penicillium austurianum: 44.47-98.85% and 75.57–94.21%; Saccharomyces cerevisiae: 52.61-88.68% and 61.20-89.95%; Mucor arcindloides: 83.78-93.13% and 62.91-97.65% and Trichoderma reesi: 52.52-80.70% and 35.31-88.13% for dead and live biomass respectively. The influence of pH on metal uptake was evaluated at pH of 2, 4, 6 and 7. A regular pattern of sorption efficiency among the dead fungi species with respect to pH was observed and the % adsorption decreased in the order pH 7 > 2 > 6 > 4 with the exception of Mucor (pH 7 > 2 > 4 > 6). Modified biomass of Aspergillus niger with oxalic acid, malic acid and ethylenediamine tetraacetic acid (EDTA) recorded 92.84%, 48.11% and 39.83% uptake of Pb respectively which correspond to 69.65%, 41.23% and 29.25% increase when compared to 28.18% of the unmodified biomass. These quantitative adsorptions demonstrate the potential application of modified biomass for the removal of Pb ion from aqueous solution.
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