In situ synthesis of gold nanoparticles embedded in a magnetic nanocomposite of glucosamine/alginate for enhancing recyclable catalysis performance of nitrophenol reduction†

In this study, we introduce an in situ synthesis technique for incorporating gold nanoparticles (AuNPs) into a magnetic nanocomposite made of glucosamine and alginate (GluN/Alg) via ionotropic gelation. GluN acted as a reducing agent for gold ions, leading to the formation of AuNPs which embedded in the nanocomposite Fe₃O₄@GluN/Alg. Analytical techniques confirmed the crystallite structure of the nanocomposite AuNPs/Fe₃O₄@GluN/Alg, which had an average size of 30–40 nm. This nanocomposite demonstrated high catalytic efficiency in reducing 2-, 3-, and 4-nitrophenols, exhibiting rapid kinetics with pseudo-first order rate constants between 1.16 × 10⁻³ s⁻¹ and 2.29 × 10⁻³ s⁻¹. The reduction rates and recyclability for nitrophenols followed the order: 4-nitrophenol > 2-nitrophenol ∼ 3-nitrophenol. These results indicate that the nanocomposite holds significant promise for customized applications in environment and medicine, positioning it as a highly versatile material.