Chitosan Schiff base for the spectrofluorimetric analysis of E-waste toxins: Pentabromophenol, Fe3+, and Cu2+ ions.

A chitosan Schiff base (SB@Chitosan) has been prepared by the condensation reaction of 5-bromosalicyldehyde and chitosan. The structural properties of SB@Chitosan have been investigated through FT-IR, ¹H NMR, PXRD, TGA, and SEM analysis. The SB@Chitosan exhibited a fluorescence emission signal centred at 501 nm (λ_exc = 340 nm). However, the signal was quenched in the presence of e-waste toxins i.e. pentabrominated phenol, Fe³⁺, and Cu²⁺ ions. Therefore, SB@Chitosan was investigated as a spectrofluorimetric probe for the recognition and quantification of Fe³⁺, Cu²⁺, and pentabromophenol in organic-aqueous medium (H₂O/DMSO; 30:70% v/v). The density-functional theory suggested the acid–base pair formation between azomethinic functionality and pentabromophenol which led to the quenching of fluorescent signal due to the photoinduced electron transfer mechanism. It also supported the mechanism of interaction between SB@Chitosan and heavy metals based on the HOMO–LUMO energy gap. The probe was also tested for practical applications like the analysis of water and soil samples. [ABSTRACT FROM AUTHOR]