Preparation, Characterization, and Catalytic Activity of Pd-Fe₃O₄@KLN Nano-composite for Reduction of 4-Nitrophenol

Abstract

In this work, we developed a Pd–Fe₃O₄@KLN nanocomposite through a straightforward and efficient synthesis route that employs kaolin (KLN) as the structural template, Fe₃O₄ as the magnetic component, and palladium nanoparticles as the active sites. Structural analyses (XRD, SEM, and XPS) confirmed that the kaolin framework remained intact while enabling the successful formation of Fe₃O₄ and a uniform distribution of Pd⁰/PdO species across the support. The resulting material acted as an excellent catalyst towards the catalytic reduction of 4-nitrophenol, achieving complete conversion within 45 seconds under suitable reaction conditions. The decay process obeyed pseudo-first order kinetics, which was fixed by its high apparent rates (5.52–6.27 min⁻¹). Temperature-dependent kinetic studies gave an activation energy of 70.24 kJ mol⁻¹, and Eyring analysis yielded ΔH# = 67.68 kJ mol⁻¹ and ΔS# = –0.01732 kJ mol⁻¹ K⁻¹. Magnetic measurements revealed superparamagnetic behavior, facilitating easy separation with an external magnet. Reusability tests showed that the catalyst preserved more than 80 % of its activity after five consecutive runs, with minimal Pd leaching (< 0.16 %). These results highlight Pd–Fe₃O₄@KLN as an environmentally friendly, magnetically recoverable, and reusable catalyst facilitating efficient reduction of nitroaromatic pollutants.

Keywords

• 4-nitrophenol reduction
• catalytic activity
• magnetic recoverable catalyst

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