Investigation of the usage of common blue mussel (Mytilus edulis) shell as adsorbent for the removal of Cu(II) and Cr(III) ions in aqueous media via adsorption method

The solid and also especially the metal ion solution wastes of heavy metal industries are rendered as pollutants to the nature due to their toxicity. Therefore, it is imperative to treat such metal ion containinng aqueous wastes before being discharged to the environment. Although a variety of methods are being used for the treatment of aqueous wastes with heavy metal content, inrecent years the use of adsorbents produced by simple methods from natural sources are becoming more prominent in the heavy metal stripping. In this study, the use of grinded common blue mussel shell (Mytilus edulis) as an adsorbent in the treatment of Cu(II) ve Cr(III) ions with adsorption, was investigated. As a result of the study it was found that the Cr(III) adsorption at 293 K was in accord with Langmuir and Freundlich isotherms, while at 303 K - 313 K it conformed with Freundlich isotherm, still at the higher temperature of 333 K it obeyed Langmuir isotherm. On the other hand, for Cu(II) at 293 K the adsorption correlated with Freudlich isotherm and at the higher temperature of 303 K it correlated with Langmuir isotherm. It was concluded that, the adsorption yield for both the Cr(III) and Cu(II) ions with the initial concentrations of 50-200 ppm, reached their maximums in betweeen 293 K – 333 K, in general at 303 K. It was found that the adsorption yield for Cr(III) with the 50 ppm initial concentration reached 96%, and with the initial concentrations raised to 100 ppm and 200 ppm the yield declined slightly, and the adsorption yield for Cu(II) with the 200 ppm initial concentration was 98% with an increasing trend with increasing initial concentration. The adsorption capacity of the adsorbent for Cr(III) ion was determined to be 18 mg/g, while its adsorption capacity for Cu(II) ion was determined as 19.5 mg/g. According to the Lagargren adsorption kinetics which is of first degree, the activation energies of Cr(III) and Cu(II) on the adsorbent were approximately 7 kJ/mol and 8 kJ/mol, respectively. When the adsorption capacity of the ground shell was compared with that of activated carbon of 16 mg/g for Cr(III) and 45 mg/g for Cu(II), it was concluded that ground common blue mussel shell could be employed as an adsorbent for the adsorption treatment of aqueous solutions of Cr(III) and Cu(II) ions. Key Words: Adsorption; Heavy Metal; Cu (II); Cr (III); Langmuir isotherm; Freundlich isotherm; Lagergren kinetics