The attachment-detachment mechanism of ionic/nanoscale/microscale substances on quartz sand in water

The attachment-detachment of heavy metal ions and suspended matter (SM), such as copper ions (Cu2+), graphene oxide (GO) and silica powders, onto a quartz sand porous medium (SiO2 particles) in water was investigated. The experimental results showed that the attachment-detachment process can be described by a nonlinear model. The detachment curves appeared as a group of parallel scanning curves. The attachment/detachment curves ranged from linear to nonlinear for copper ions, GO and silica powders (ranging from ions to particles). Finally, a unified static attachment-detachment model was established. The attachment mechanism mainly involved the interfacial electrostatic attraction between SM and the solid matrix, the formation and directional adjustment of metal bonds, and the complementary molecular structure characteristics of the different materials. The irregular motions of Cu2+, GO and silica powder were significantly enhanced by increasing the temperature. [Display omitted] •Differences in the attachment mechanisms of ionic/nanoscale/microscale substances onto sand are revealed.•A unified nonlinear static attachment-detachment model in water is established.•The model is explained by metallographic microscopy and functional group characterization of SM.•Increasing the temperature promotes irregular motion of Cu2+, GO and silica powders.