Enhanced Removal of Dissolved Humic Acid from Water Using Eco-Friendly Phenylalanine-Modified-Chitosan Fe3O4 Magnetic Nanoparticles

High-efficient adsorbents with eco-friendly and easy recycling features remain to be pursued in wastewater treatment. In this work, one green magnetic nano-composite, phenylalanine-modified-chitosan Fe3O4 (Fe3O4@chitosan@Phe), was prepared and its adsorption behavior for humic acid from water was investigated. Our results showed that the modified phenylalanine could promote the maximum adsorption quantites of humic acid by Fe3O4@chitosan@Phe than Fe3O4@chitosan, and the adsorption processing followed the pseudo second-order kinetic model. Either the Langmuir or Freundlich isotherm model could not appropriately describe the adsorption processing, implying the adsorption process is more complex than typical monolayer, or multilayer adsorption. The functional groups (amidogen, phenyl) of phenylalanine could strengthen the interaction between Fe3O4@chitosan@Phe and humic acid molecules through electrostatic interaction, pi-pi interaction, and hydrogen bonds. The Fe3O4@chitosan@Phe exhibited good reusability after running eight adsorption-regeneration cycles. This work proposes a new strategy to design eco-friendly magnetic adsorbents, which meets the requirement of modern green chemistry.