Facile fabrication and characterization of kraft lignin@Fe3O4 nanocomposites using pH driven precipitation: Effects on increasing lignin content

This work offers a facile fabrication method for lignin nanocomposites through the assembly of kraft lignin onto magnetic nanoparticles (Fe3O4) based on pH-driven precipitation, without needing organic solvents or lignin functionalization. Kraft lignin@Fe3O4 multicore nanocomposites fabrication proceeded using a simple, pH-driven precipitation technique. An alkaline solution for kraft lignin (pH 12) was rapidly injected into an aqueous-based Fe3O4 nanoparticle colloidal suspension (pH 7) under constant mixing conditions, allowing the fabrication of lignin magnetic nanocomposites. The effects of increasing lignin to initial Fe3O4 mass content (g/g), increasing in ratio from 1:1 to 20:1, are discussed with a complete chemical, structural, and morphological characterization. Results showed that nanocomposites fabricated above 5:1 lignin:Fe3O4 had the highest lignin coverage and content (>20%), possessed superparamagnetic properties (Ms approximate to 45,000 A. m(2)/kg(2)); had a negative surface charge (-30 mV), and formed multicore nanostructures (D-H approximate to 150 nm). The mullicore lignin@Fe3O4 nanocomposites allowed rapid magnetically induced separations from suspension. After 5 min exposure to a rare-earth neodymium magnet (1.27 mm x 127 mm x 5.08 mm), lignin@Fe3O4 nanocomposites exhibited a maximum methylene blue removal efficiency of 74.1% +/- 7.1%. These nanocomposites have potential in magnetically induced separations to remove organic dyes, heavy metals, or other lignin adsorbates. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This work presents a facile method for fabricating lignin nanocomposites by assembling kraft lignin onto magnetic nanoparticles through pH-driven precipitation. The fabricated nanocomposites exhibit high lignin coverage and content, superparamagnetic properties, and multicore nanostructures, allowing rapid magnetically induced separations and efficient removal of organic dyes such as methylene blue. These nanocomposites have potential applications in removing organic dyes, heavy metals, and other lignin adsorbates using magnetically induced separations.