Two Independent Routes to Synthesize Identical Silicas by Grafting Ethylenimine or 2-Aminoethanethiol, Their Cation Adsorbing Abilities, and Thermodynamic Data

摘要: Abstract The same grafted silica gel surface was obtained through two distinct procedures: (i) by immobilization of the compound 2-aminoethanethiol on precursor 3-chloropropylsilylsilica in a heterogeneous method, and (ii) reacting ethylenimine with 3-mercaptopropyltrimethoxysilane to give new silylating agent, which anchored homogenous method. first gave 0.70 mmol g−1 molecules covalently bonded per gram silica. This value contrasts that homogeneous conditions, 1.74 pendant groups Both organofunctionalized surfaces have ability adsorb divalent cations from aqueous nitrate solution. adsorption performed using batchwise process maximum capacity followed sequence Cu>Ni>Co Ni>Cu>Co for prepared methods, respectively. Through calorimetric titrations, thermodynamic values cation-basic center interactions were obtained. Exothermic enthalpy results all interactive processes. calculated free Gibbs energy is agreement spontaneity reactions positive entropy are favorable this system.