Control of nanoscale forces on virus transport in porous media with surface heterogeneity

Surface heterogeneity significantly influences virus transport and retention in porous media. Previous studies have mainly provided qualitative interpretations based on column experiments and theoretical predictions, leaving limited quantitative understanding of microscale mechanisms. This study integrated nanoscale force analysis, microscale surface morphology characterization, and column-scale transport experiments to quantify the migration and retention of bacteriophages MS2 and T4 in surface-heterogeneous porous media. The results showed that increased surface roughness heterogeneity enhanced virus retention, with deposition increasing by 18% for MS2 and 14% for T4. T4 was more sensitive to increasing roughness than MS2, and its attachment efficiency showed a non-monotonic response. Surface chemical heterogeneity shifted the dominant virus-surface interaction regime from repulsive to attractive. This transition reduced breakthrough concentrations by 2-3 orders of magnitude and increased virus deposition to >95%. Nanoscale force measurements supported the column-scale results and further showed that surface roughness heterogeneity mainly increased attachment probability by expanding the spatial range of virus-surface interactions, while exerting a smaller effect on force magnitude, with attractive forces increasing threefold. In contrast, surface chemical heterogeneity markedly increased interaction force magnitudes, with attractive forces increasing 14-fold, thereby promoting more stable binding configurations on metal oxide surfaces and reducing the likelihood of virus desorption. These findings clarify the link between nanoscale interactions and macroscopic deposition behavior and provide mechanistic constraints for improving groundwater virus transport models.