Response Surface Methodology Optimization of Cobalt (II) and Lead (II) Removal from Aqueous Solution Using MWCNT-Fe3O4 Nanocomposite

The present investigation describes the evaluation of feasibility of MWCNT-Fe3O4 nanocomposite toward adsorptive removal of Co(II) and Pb(II) from aqueous solution in batch mode. The Fe3O4–MWCNT hybrid was prepared using a simple one-pot strategy via in situ growth of Fe3O4 magnetic nanoparticles onto the surface of the MWCNTs. The Fe3O4–MWCNT hybrid was characterized by X-ray diffractometry and Field Emission Scanning Electron Microscopy (FESEM).
A Response Surface Methodology (RSM) with a Central Composite Design (CCD) was employed to evaluate the effects of solution pH, contact time, temperature, initial heavy metal concentration and adsorbent dosage on the removal efficiency of the heavy metals. Results of analysis of variance (ANOVA) showed that the initial metal concentration and absorbent dosage and their interaction effect were the most significant parameters for Co(II) ion removal. Adsorbent dosage, pH and initial metal concentration had significant influences on the removal efficiency of Pb(II) ions. The optimum pH, time, temperature, initial concentration of metals and adsorbent dosage were found to be 6.5,25 min, 40 °C, 35 mg/L, and 48.3 mg/50mL, respectively. Maximum removal of Pb(II) and Co(II) in optimum condition was 90.2 and 79.34% respectively. Results indicated that nanocomposite can be used as an effective adsorbent for effluent decontamination especially in Pb–Co bearing wastewaters. The equilibrium data were well fitted by the Langmuir model. The removal mechanism of metal ions followed adsorption and ion exchange processes.