Facile synthesis of recoverable superparamagnetic AgFeO2@Polypyrrole/SiO2 nanocomposite as an excellent catalyst for reduction and oxidation of different dyes in wastewater

Abstract

AbstractFabrication of a triple‐component nanocomposite system having a unique design and unusual property combinations offers a special chance to take advantage of all components and overcome the limitations of mono nanoparticles (NPs). Novel superparamagnetic AgFeO2@polypyrrole/SiO2 (AgFeO2@PPy/SiO2) triple‐component nanocomposite was synthesized in facile three‐step method using (i) coprecipitation, (ii) in situ chemical oxidative polymerization, and (iii) Stöber process. The structure and morphology of the nanocomposite were characterized by Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The triple nanocomposite has a drastic catalytic effect as compared with AgFeO2@PPy core–shell NPs and AgFeO2 NPs. The rate constant of chromotrope 2R reduction followed the order: AgFeO2@PPy/SiO2 (0.9209 min−1) > AgFeO2@PPy (0.2274 min−1) > AgFeO2 (0.1365 min−1). AgFeO2@PPy/SiO2 exhibited high catalytic recyclable performance towards the degradation of different kinds of dyes either by reduction (chromotrope 2R, tartrazine, and methylene blue) or by oxidation (methylene blue, aniline blue, and methyl violet 2B) from aqueous solution. The degradation percentage for the reduced dyes was 99.38%, 98.64%, and 98.17% and for the oxidized dyes was 75.84%, 99.34%, and 91.79%, respectively. Batch mode catalytic study was conducted with the nanocomposite to determine the maximum removal of tartrazine and aniline blue under different operational parameters was 99.5% and 99.34%, respectively. The recovery and reusability of the AgFeO2@PPy/SiO2 nanocomposite were studied using the reduction of tartrazine and the oxidation of aniline blue. Thirteen consecutive recovery reaction cycles were performed for the reduction process and nine cycles for the oxidation reaction. All the reactions revealed high stability and constant efficiency of the catalyst. The maximum percentages were 99.5% for the reduction and 99.34% for the oxidation of dyes. These values decreased through the cycles to 76.35% and 79.70% for reduction and oxidation, respectively. Based on the experimental results obtained, the synthesized materials proved to have a high potential for the removal of all investigated dyes from an aqueous solution.