Organotrialkoxysilane-Functionalized Prussian Blue Nanoparticles-Mediated Fluorescence Sensing of Arsenic(III)

Prussian blue nanoparticles (PBN) exhibit selective fluorescence quenching behavior with heavy metal ions; in addition, they possess characteristic oxidant properties both for liquid-liquid and liquid-solid interface catalysis. Here, we propose to study the detection and efficient removal of toxic arsenic(III) species by materializing these dual functions of PBN. A sophisticated PBN-sensitized fluorometric switching system for dosage-dependent detection of As³⁺ along with PBN-integrated SiO₂ platforms as a column adsorbent for biphasic oxidation and elimination of As³⁺ have been developed. Colloidal PBN were obtained by a facile two-step process involving chemical reduction in the presence of 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane (EETMSi) and cyclohexanone as reducing agents, while heterogeneous systems were formulated via EETMSi, which triggered in situ growth of PBN inside the three-dimensional framework of silica gel and silica nanoparticles (SiO₂). PBN-induced quenching of the emission signal was recorded with an As³⁺ concentration (0.05-1.6 ppm)-dependent fluorometric titration system, owing to the potential excitation window of PBN (at 480-500 nm), which ultimately restricts the radiative energy transfer. The detection limit for this arrangement is estimated around 0.025 ppm. Furthermore, the mesoporous and macroporous PBN-integrated SiO₂ arrangements might act as stationary phase in chromatographic studies to significantly remove As³⁺. Besides physisorption, significant electron exchange between Fe³⁺/Fe²⁺ lattice points and As³⁺ ions enable complete conversion to less toxic As⁵⁺ ions with the repeated influx of mobile phase. PBN-integrated SiO₂ matrices were successfully restored after segregating the target ions. This study indicates that PBN and PBN-integrated SiO₂ platforms may enable straightforward and low-cost removal of arsenic from contaminated water.