Effective NH2-grafting on mesoporous SBA-15 surface for adsorption of heavy metal ions

Abstract Utilizing the reactions between toluene diisocyanate (TDI), silanol, and ethylenediamine (EDA), NH 2 groups were successfully grafted on mesoporous SBA-15 surface without any destroy to the mesostructure. TDI was employed as a ‘bridge’ molecule whose one NCO group was used to link SBA-15 surface silanols and the other one was left to link EDA. Such NH 2 -grafting is highly effective for a high loading amount of NH 2 groups on SBA-15 because the special stepwise grafting can avoid amino/silanol and amino/amino interactions. Subjected to remove toxic heavy metal ions in aqueous solution, the obtained NH 2 -SBA-15 showed very high adsorption rates 99.4%, 100%, 99.7%, 98.7% and 99.9% for Cu 2+ , Zn 2+ , Cr 3+ , Ni 2+ and Cd 2+ , respectively, which should be attributed to the strong complexation reactions between metal ions and grafted NH 2 groups.