Sepiolite functionalized with N-[3-(trimethoxysilyl)propyl]-ethylenediamine triacetic acid trisodium salt. Part II: Sorption of Ni2+ from aqueous solutions

Abstract

sorption of Ni2+ on the sepiolite functionalized by covalent grafting of N-[3-(trimethoxysilyl)propyl]ethylenediamine triacetic acid trisodium salt, MSEAS, was studied in batch experiments as a function of the initial metal concentration, the equilibration time, pH value, and temperature. The modification of sepiolite resulted in an enhanced Ni2+ retention with a capacity of 0.261 mmol/g at 298 K. The retention of Ni2+ ions occurred dominantly by specific sorption and exchange of Mg2+ ions from the sepiolite structure. The sorption process followed pseudo-second-order kinetics. The sorption equilibrium results were best described by the non-linear form of the Langmuir Sorption Equation. The values of the thermodynamic parameters (enthalpy, free energy and entropy) were calculated from temperature dependent sorption isotherms and these values showed that the sorption of Ni2+ onto modified sepiolite was endothermic. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 i FP7 NANOTECH FTM No. 245916]

Keywords

• functionalized sepiolite
• sorption
• Ni2+
• kinetics
• thermodynamics