High-Value Valorization of Agricultural Waste Biomass into Lignin-Based Magnetic Nanocomposites: Multifunctional Catalytic Systems with Near-Infrared-Responsive Liquid Marbles for Controllable and Sustainable Dye Removal

The development of green, efficient, and sustainable noble metal nanocatalysts is critical for addressing industrial wastewater pollution. Herein, we report a high-value utilization strategy for agricultural waste biomass by transforming lignin nanoparticles (LNPs) derived from agricultural residues into multifunctional supports for Fe ₃O ₄and Pd nanoparticles. Through a two-step process─antisolvent self-assembly followed by in situ reduction─LNPs@Fe ₃O ₄@Pd magnetic nanocomposites are synthesized, combining lignin’s inherent eco-friendly properties with the magnetic recyclability of Fe ₃O ₄and the catalytic activity of Pd. The catalytic study showed that LNPs@Fe ₃O ₄@Pd presented excellent catalytic efficiency for the fade of methylene blue (catalytic rate constant is 5.89 min ^–1). The incorporation of stable superparamagnetism imparted the LNPs@Fe ₃O ₄@Pd with an exceptional cycling performance. Additionally, the nanocomposites exhibit robust photothermal conversion capabilities, enabling the construction of NIR laser-responsive liquid marbles via simple assembly. These liquid marbles combine magnetic separability and light-triggered controllability, offering a dynamic and reusable platform for dye wastewater treatment. Consequently, LNPs@Fe ₃O ₄@Pd and their liquid marble assemblies hold significant potential for industrial-scale applications in sustainable dye removal and beyond.