Improved synthesis of silica-gel-based dendrimer-like highly branched polymer as the Au(III) adsorbents

• Silica-gel-based diethylenetriamine typed dendrimer-like highly branched polymer adsorbents were prepared.
• The combination synthetic methods of homogeneous and heterogeneous were used.
• The maximum adsorption capacities for Au(III) were 2.09 and 2.12 mmol g−1 for two adsorbents.
• The adsorbents had excellent selectivity for Au(III) in binary systems metal solution.

Silica-gel-based adsorbents (SG-DETA and SG-DETA2) grafting of dendrimer-like highly branched polymer were prepared by an improved methods of a combination of homogeneous and heterogeneous. FTIR analysis, SEM analysis, pore structure analysis and thermodynamic analysis manifested that dendrimer-like highly branched polymer was successfully grafted onto the silica surface. The results of the adsorption thermodynamics and kinetics of the as-synthesized SG-DETA and SG-DETA2 showed the adsorbents had good adsorption capacity for Au(III), and the best interpretation for the experimental data was given by the Langmuir isotherm equation. The maximum adsorption capacity for Au(III) were 2.09 and 2.12 mmol g−1 of SG-DETA and SG-DETA2 at 35 °C, respectively. Moreover, the study indicated the adsorption kinetics of SG-DETA and SG-DETA2 could be modeled by the pseudo-second-order rate equation wonderfully. The SG-DETA and SG-DETA2 adsorbents had excellent adsorption selectivity for Au(III) in binary metal solution systems. Therefore, the high adsorption capacity make these adsorbents have significant potential for Au(III) uptake from aqueous solutions using adsorption method.