Tunable amine-functionalized silsesquioxane-based hybrid networks for efficient removal of heavy metal ions and selective adsorption of anionic dyes

By changing the acid scavenger from NEt3 to NaHCO3, two novel kinds of amine-functionalized silsesquioxane (SQ)-based hybrid networks (PCS-N1, PCS-N2) with different molar ratios of -NH2/NH- and NH3+ were successfully prepared via nucleophilic substitution of octa(3-chloropropyl) silsesquioxane (SQ-Cl8) with triaminoethylamine, respectively. Both networks were fully characterized by FTIR, SEM, TEM, oS, BET, TGA, WCA and solid-state 13C and 29Si NMR spectra. No porosity was observed for these two hybrid networks; however, they exhibited good thermal stability and hydrophilicity. To our surprise, they strongly adsorb heavy metal ions due to ion exchange and coordination. The adsorption capacities for Ag+ and Hg2+ are as high as 358 +/- 6 and 721 +/- 5 mg g+1, respectively. More interestingly, PCS-N1 can selectively adsorb the anionic dye methyl orange with a capacity as high as 731 +/- 13 mg g+1. Furthermore, they regenerate easily and offer potential for water purification. This work provides a new approach to prepare and tune amine-functionalized SQ-based networks for multipurpose.

Automated summary

By changing the acid scavenger, two novel kinds of amine-functionalized silsesquioxane-based hybrid networks were successfully prepared, exhibiting high adsorption capacities for heavy metal ions and dyes, as well as good thermal stability and hydrophilicity.