SORPTION OF HEAVY METAL IONS FROM AQUEOUS SOLUTION BY GLAUCONITE

摘要

In the present paper the results of heavy metals sorption on glauconite were presented in terms of their initial concentration, contact time, ionic strength and pH of the solutions. A better match of the results of sorption was found for adsorption isotherms according to the Langmuir equation. Glauconite manifested the highest sorption capacity towards lead ions-9.12 mg/g, lower towards Cd(Ⅱ)-3.44 mg/g and the lowest towards Zn(Ⅱ)-3.07 mg/g and Cu(Ⅱ)-2.96 mg/g. After the heavy metal sorption, a regeneration of glauconite and further sorption are possible. The highest regeneration equaled 80% with the initial concentration of 5 mg/L. With the increase of the concentration it decreased to 56%. In further regeneration cycles, desorption and sorption decreased proportionally by 2-3%. The optimum contact time to obtain the equilibrium state amounted to 180 minutes. The pseudo-second-order equation adjusts very well the experimental data, as it can be noted by the high correlation coefficients, and close values of sorption capacity calculated on the basis of the equation of pseudo-second-order to the values obtained experimentally. In the metal solutions of pH=2, pH=4, pH= 6 and with a variable NaClO_4 electrolyte concentration in the range of 0.00-0.05 M, there was a significant decrease in sorption compared to the solution without electrolytes. The heavy metal removal efficiency increased with the increase in pH of the stock solution. The highest sorption of Pb(Ⅱ) ions was reached at pH=6.3, Cu(Ⅱ) at pH=7.2, Zn(Ⅱ) pH=7.6 when it comes to ions of Cd(Ⅱ) it was reached at pH equal to 9.