Grafted silica gel for removal of heavy metal ions

Abstract

In this study, the silica gel (SG) surface was activated and then, immobilized with N-(2-chlorobenzylidenc)-3-(triethoxysil)propan-1 -amine (CBTPA) to improve its adsorption properties against heavy metal ions. The prepared SG-CBTPA was characterized with a variety of techniques, including Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis (DTA/TG), scanning electron microscopy (SEMEDX), and zeta potential measurement. Batch method was used for the adsorption study of Cd (II), Cu (II) and Co (II) ions. The amount of adsorbed Cd (II), Cu (II) and Co (II) ions was measured by Perkin Elmer Optima 7300 DV ICP-OES. The effects of concentration, temperatureand pH to the adsorption capacity of SG-CBTPA were investigated. The isoelectrical point of SG suspensions was changed by modification. The adsorption experiments showed that the adsorption capacity of SG-CBTPA to metal ions vv-as increased with increasing initial concentration. pH and temperature. SG-CBTPA showed a higher adsorption capacity than SG.The results were applied to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm equations and Langmuir adsorption isotherm was in good agreement with the experimental data, In addition, thermodynamic parameters such as free energy (AG), entropy (AS), and enthalpy (AH) were calculated from the sorption results and used to explain the adsorption mechanism. The results indicated that this modified adsorbent could successfully be employed in the adsorption of Cd (II), Cu (II) and Co (II) ions from aqueous solutions.