Multifunctional Fe3O4@SiO2@Ag@Ag2ONCs was synthesized for its dual ability as a colorimetric sensor for
detection and Fenton-like catalytic degradation of parabens. The biosynthesis of Ag@Ag2ONCs performed using
algae extracts. The nanocomposite uses the synergistic advantage of the magnetic properties of Fe₃O₄ and the
catalytic activity of Ag@Ag₂O, thereby increasing the efficiency of hydroxyl radicals. The Fenton-like mechanism
employed in this work operates efficiently at an alkaline pH (pH 8), enhancing the oxidation of parabens using
H2O2. Kinetic measurements were completed within 10 min, which showed the excellent catalytic properties of
composite. The method provided 3.0–40.0, 4.0–100.0, 4.0–100.0 and 8.0–100.0 μM linear dynamic ranges with
detection limits of 0.85, 1.02, 2.5, and 2.47 μM for methylparaben (MP), butylparaben (BP), propylparaben (PP)
and benzyl paraben (BenzylP), respectively. The kinetic profiles well fit the pseudo-first-order model. The
apparent rate constant value of 3.0 × 10− 4 s
− 1 for BenzylP, PP, and BP and 4.0 × 10− 4 s
− 1 for MP was obtained.
Therefore, the method was also used for the quantification of parabens in (spiked) seawater and algae samples,
and well recovery values were obtained. The results showed that the Fe₃O₄@SiO₂@Ag@Ag₂ONCs can efficiently
degrade parabens in real samples, such as seawater and algae. Also, indirect confirmation experiments are used
to investigate the production of OH•
. Spectrophotometric degradation of MP using NaBH4 and methylene blue
(MB) using H2O2 were performed in the presence and absence of the composite. Both degradations occurred very
rapidly in the presence of the composite also the MB spectral shape changed. These results, together with the
kinetic data, confirm the generation of OH• in the proposed Fenton-like mechanism.
