A central composite face-centered design was used to study and to optimize lead biosorption from
aqueous solution on
Aspergillus terreus
biomass. Four factors such as stirring speed, temperature, solution pH and
biomass dose at different levels were studied.The hierarchical quadratic model were established by adding replicates at
the central point and axial points to the initial full factorial design (2
4). The percentage removal of lead was affected by
biomass dose, pH, and interactions between pH and biomass dose, pH and stirring speed, pH and temperature. The
hierarchical quadratic model described adequately the response surface based on the adjusted determination coefficient
(R
2Adj= 0.97) and the adequate precision ratio (42.21). According to this model, the optimal conditions to remove lead completely from aqueous solutions (at initial lead concentration of 50 mg/L and solutions of 100 mL) with
Aspergillus
terreus were at pH 5.2, 50°C, stirring speed of 102/min and a biomass dose of 139 mg.The response surface methodology
can be used to determine the optimal conditions for metal adsorption on several adsorbents. In addition, results
reported in this research demonstrated the feasibility of employing
A. terreus as biosorbent for lead removal.