In this work, various variables that affected the lead(II) removal efficiency by thermally activated adsorbent prepared from Spirogyra species were simultaneously optimized using the experimental design method. Preliminary experiments showed that the effect of four variables of adsorbent dosage (0.1 – 1.0 g/L), sample pH (3 – 9), initial concentration (50 - 100 mg/L), and temperature (25 – 45 oC) were important. Therefore, response surface methodology (RSM) based on central composite design (CCD) was performed to find a relationship between these factors on lead(II) removal efficiency as response. The statistical parameters of the derived model were R2 = 0.9899 and F value = 10852.54. The response surface diagrams were plotted based on the defined model to show the effects of the variables on lead(II) adsorption efficiency. Finally, non-linear optimization was carried out and under the defined optimum conditions the predicted lead(II) removal efficiency with 95% confidence level was found 97.6±2.3%, which is in agreement with the experimental response of 96.9±1.3%.

In this work, various variables that affected the lead(II) removal efficiency by thermally activated adsorbent prepared from Spirogyra species were simultaneously optimized using the experimental design method. Preliminary experiments showed that the effect of four variables of adsorbent dosage (0.1...