Potassium Hydroxide Activated Peanut Shell as an Effective Adsorbent for the Removal of Zinc, Lead and Cadmium from Wastewater

The toxic heavy metals, as non-biodegradable pollutants, have become a serious threat to aquatic environment. This study aimed to assess the efficiency of the low cost, available and environment-friendly peanut shell as an effective adsorbent for the removal of Zn, Pb and Cd from wastewater. The peanut shell was prepared by carbonization by pyrolysis process at 550 °C, activated with 7M potassium hydroxide(KOH) at 750 °C, and then characterized by using Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analysis. The optimum conditions for metal ions adsorption were investigated as a function of various parameters. The optimum conditions included: pH of 6, initial metal concentrations of 20 mg/l for Pb and Zn as well as 40 mg/l for Cd, adsorbent mass of 2 g, optimum temperature of 45 °C and the preferable contact time of 60 min. The removal percent for the studied metal ions exceeded 98%. The adsorption isotherm showed that the Langmuir model was the best fitted model for the metal ions adsorption onto activated peanut shell surface, and the kinetic of adsorption followed the pseudo-first order model. The obtained results showed that the KOH-activated peanut shell possess higher adsorption efficiency for the removal of the studied metal ions from wastewater.