Removal of Heavy Metal Ions from Industrial Wastewater by Modified Sunflower Seed Husks: Adsorption and Kinetics

Abstract

Modified sunflower seed husk was used as adsorbent to remove Ni (II), Zn (II), Pb (II), and Cd (II) from synthetic and automotive industrial wastewater. Sunflower husk was treated by 0.8 M K2CO3, 400°C (400-K2CO3MSSH). The adsorption experiments were conducted with an initial metal ion concentration of 100 mg/L and pH of 5. In a batch experiment of single metal ion synthetic wastewater, it was found that the adsorption percentages of Ni (II), Zn (II), Pb (II), and Cd (II) were 96.50, 97.03, 96.98 and 97.54, respectively. For mixed-ions synthetic wastewater, competitive removal percentage of Ni (II), Zn (II), Pb (II), and Cd (II) were 87.16, 94.30, 98.02 and 97.01, respectively. Wastewater from the automotive industry containing Ni (II), and Zn (II) had an efficiency removal of 75.25% and 87.50%, whereas the lathe work had 78.18% and 88.34% of Zn (II) and Pb (II) removal respectively. The experimental results were found to fit the Langmuir isotherm model. The kinetics of adsorption showed the pseudo-second order model in both single and mixed synthetic wastewater. For single ion adsorption, it was found that the pseudo second order rate constant were 0.032, 0.134, 0.108, and 0.156 g/mg-min and the adsorption capacity at equilibrium were 7.39, 10.56, 10.76 and 10.52 mg/g for Ni (II) Zn (II) Pb (II) and Cd (II), respectively.