Adsorption of FeCl3, CuCl2 and ZnCl2 on silsesquioxane 3-n-propylpyridiniumchloride polymer film adsorbed on Al2O3 coated silica gel

Silsesquioxane 3-n-propylpyridiniumchloride polymer (abbreviated as SiPyCl), was used to coat SiO2/Al2O3 substrate surface to form the chemically modified solid SiO2/Al2O3/SiPyCl having the specific surface area SBET= 233 m2 g−1. The resulting polymer film was strongly adhered to the surface by means of ≡Al–O–Si bonding (where ≡Al stands for Al2O3 grafted on SiO2 surface) and presented an ion exchange capacity of 1.04 mmol g−1. The metal halides, MClz [M= Fe(III), Cu(II) and Zn(II)], were adsorbed by the modified solid from ethanol solutions as neutral species by forming the surface anionic complexes described by the equation: mSiO2/Al2O3/SiPyCl+MClz⇆(SiO2/Al2O3/SiPy+)m[MClz+m]m−, where FeCl4−, ZnCl42− have tetrahedral and CuCl42- distorted tetrahedral symmetries. The equilibrium coefficients, K, determined for each complex species showed that SiO2/Al2O3/SiPyCl has a high affinity for the metal ions. The following values expressed as log K were found: Cu=3.0, Zn=3.5 and Fe=3.0. The material could efficiently preconcentrate these metal ions from an ethanol solutions and release them in aqueous solution.