Poly(ethyleneimine) functionalized organic-inorganic hybrid silica by hydrothermalassisted surface grafting method for removal of nickel(II)

Poly(ethyleneimine)-functionalized organic-inorganic hybrid silica adsorbent was synthesized by hydrothermal-assisted surface grafting technique for the removal of Ni(II) ions from aqueous solution, and was characterized by FT-IR, nitrogen adsorption and the static adsorption-desorption experiment method. The results indicated that the maximum static adsorption capacity of Ni(II) on poly(ethyleneimine)-functionalized hybrid silica adsorbent by hydrothermal heating method was 1.6 times as much as the conventional heating method. The poly(ethyleneimine)-functionalized hybrid silica adsorbent offered a fast kinetics for the adsorption of Ni(II), had a substantial binding capacity in the range of pH 4-8 and could be used repeatedly. The Langmuir adsorption model was more favorable than the Freundlich and Dubinin-Radushkevich adsorption models. The adsorption followed a pseudo-second-order model compared with pseudo-first-order model. Various thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated that the adsorption process was spontaneous and endothermic. The results showed that poly(ethyleneimine)-functionalized hybrid silica adsorbent could be employed as an effective material for the removal of Ni(II) ions from aqueous solution.