Removal of transition metal ions from aqueous solutions by adsorption using a novel hybrid material silica gel chemically modified by triethylenetetraminomethylenephosphonic acid

Abstract A novel inorganic–organic hybrid material silica gel chemically modified by triethylenetetraminomethylenephosphonic acid (denoted as GH-T-P) has been synthesized and characterized. Its adsorption properties GH-T-P for Au(III), Hg(II), Cu(II), Pb(II), Co(II), Zn(II), Ni(II), Cr(III) and Cd(II) have been investigated, and the research results revealed that GH-T-P has the best adsorption capacity for Au(III). Furthermore, the adsorption selectivity results of GH-T-P for Au(III) displayed that GH-T-P had excellent adsorption for Au(III) in binary ions systems, especially in the systems of Au(III)–Zn(II), Au(III)–Ni(II) and Au(III)–Cr(III). Langmuir and Freundlich isotherm models were applied to analyze the experimental data, and the best interpretation for the experimental data was given by the Langmuir isotherm equation. GH-T-P could reach to the saturation adsorption capacity within 2 h, and its excellent adsorption capacity for Au(III) was 266.49 mg/g when the initial solution concentration was 2.0 mmol/L at 35 °C. Moreover, the research revealed that its adsorption kinetics can be modeled by pseudo-second-order rate equation wonderfully, and the thermodynamic parameters Δ G , Δ H and Δ S were −20.79 kJ mol −1 , 5.17 kJ mol −1 , and 84.37 J K −1  mol −1 , respectively. Thus, this novel hybrid material silica gel chemically modified by triethylenetetraminomethylenephosphonic acid GH-T-P is favorable and useful for the uptake of Au(III), and the high adsorption capacity and good reproducibility make it a good promising candidate material for the precious metal uptake.