4-amine-2-mercaptopyrimidine modified silica gel applied in Cd(II) and Pb(II) extraction from an aqueous medium

This paper discusses silica surface modification by a process involving a two-step reaction: anchoring of a silylating agent, followed by an attachment of a 4-amino-2-mercaptopyrimidine molecule. The modified material (Si-BP) was successfully characterized by the FTIR spectra, which revealed amine absorption bands, and through ¹³C and ²⁹Si NMR spectra, which confirm the proposed structure of the modified silica (Si-BP). Si-BP was used to extract cadmium and lead from an aqueous medium at 298 K. The Si-BP kinetics towards metal ions was very fast, i.e., about 10 minutes, although extraction was significantly impaired at pH 3. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum extraction capacity was 0.193 and 0.387 mmol g^-1 for Cd(II) and Pb(II), respectively. An analysis of the Ø values lead to the inference that the resulting metal ligand complex was type 1:1.