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), NH2 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 NH2-grafting is highly effective for a high loading amount of NH2 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 NH2-SBA-15 showed very high adsorption rates 99.4%, 100%, 99.7%, 98.7% and 99.9% for Cu2+, Zn2+, Cr3+, Ni2+ and Cd2+, respectively, which should be attributed to the strong complexation reactions between metal ions and grafted NH2 groups. [Copyright &y& Elsevier]