The Migration Properties of Sodium Alginate-Modified Sulfurized Nanoscale Zerovalent Iron in Porous Media

Nanoscale zerovalent iron (nZVI) is a promising material for groundwater remediation, yet its effectiveness is often limited by aggregation and poor mobility. A packed column experiment was conducted to investigate the migration properties of nZVI modified with sodium sulfide and sodium alginate (SA@SNZVI). Characterization and sedimentation tests confirmed that sodium alginate effectively prevents the aggregation of nZVI. Column experiments coupled with convection-diffusion modeling demonstrated that SA@SNZVI exhibits shear-thinning behavior, characteristic of pseudoplastic fluids. This behavior reduces spatial clogging and enhances the particle mobility, especially at higher concentrations. Breakthrough curves indicated a more gradual transport of particles with reduced retention in the porous media. In dual-column experiments, sodium alginate reduced the permeability gap between coarse and fine sand, thereby improving the filling efficiency and mitigating preferential flow effects. These findings provide theoretical insights and practical guidance for optimizing nZVI-based in situ remediation technologies, thereby facilitating their application in complex subsurface environments.