The coupled migration model of two-phase flow with nonlinear adsorption-desorption patterns exhibiting delays

Abstract

Static adsorption-desorption experiments were conducted at four different temperatures, revealing that increasing temperature enhances both adsorption and desorption, with the increment in adsorption being greater than that in desorption. A nonlinear adsorption-desorption model with hysteresis effects was employed to describe the adsorption-desorption processes among multiphase suspended substances, confirming that the adsorption-desorption of suspended particles on the solid-phase matrix at high temperatures follows a nonlinear relationship. Based on SEM, Zeta potential, and DLVO theory calculations, it was found that both increasing temperature and the addition of lead ions reduce the interfacial energy between the red mud and quartz sand surfaces, facilitating better fixation of lead ions within the porous medium. EDX, XRD, FTIR, and XPS experimental results indicate that carbonate ions in red mud can form precipitates with lead ions, exhibiting different chemical reaction characteristics under varying pH conditions. A two-phase flow migration model for contaminant ions and suspended particles was established based on granular thermodynamics. The model's validity and practicality were confirmed through coupled migration experiments of contaminants and suspended particles under different seepage rates and injection concentrations. The simulation results accurately reflect the adsorption-desorption behavior of contaminants and suspended particles during their migration within the solid-phase matrix.