Activated Periwinkle Shells for the Binding and Recognition of Heavy Metal Ions from Aqueous Media

The potential of a low-cost periwinkle shell powder (PSP) for the adsorption of Cr(II) and Zn(II) ions from aqueous media was investigated by batch mode. The PSP produced was chemically activated with 0.1M H2SO4. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetry were used to characterize the structure and morphology of the PSP sorbent. The obtained results showed that PSP possessed good recognition toward Cr and Zn. The effect of various parameters such as contact time, initial concentration, pH and adsorbent dosage was studied to optimize the conditions for maximum adsorption. The optimum contact time, adsorbent dosage and pH, were found to be at 120 min, 1.2g and pH 6 respectively for both metal ion. The experiment showed that when the initial metal ion concentration was increased from 20 mg/L up to 100 mg/L, the adsorption capacity of PSP increased from 0.67 to 4.14 mg/g and 0.61 to 3.65 mg/g for Cr and Zn respectively. The mechanism for the adsorption of the metal ions was found to follow Langmuir isotherm model.