A Unified Force and Torque Balance for Colloid Transport: Predicting Attachment and Mobilization under Favorable and Unfavorable Conditions

Abstract

Colloid attachment and detachment behaviors concern a wide range of environmental contexts but have typically been mechanistically predicted exclusive of one another despite their obvious coupling. Furthermore, previous mechanistic prediction often addressed packed column contexts, wherein specific forces and torques on the colloid could not be well-constrained, preventing robust predictions. These weaknesses were addressed through direct observation experiments under conditions where perfect sink assumptions fail and allow calibration of the contact between the colloid and collector. Attachment and flow perturbation experiments in the presence of colloid–collector attraction (favorable conditions) permitted calibration of contact parameters without the complexity that comes with colloid–collector repulsion (unfavorable conditions). Combining calibrated contact parameters with discrete representative nanoscale heterogeneity, developed to predict unfavorable attachment, provided an independent means to predict unfavorable detachment. The result was mechanistic prediction of colloid attachment and detachment that quantitatively agreed with experimental observation for both ionic strength and flow perturbation results, improving significantly upon previous qualitative prediction.

Multiscale dynamics of colloidal deposition and erosion in porous media

“…3A. As particle injection continues, these deposits continue to grow, as shown in movie S2, suggesting that the hydrodynamic stresses due to fluid flow are sufficient to overcome any possible electrostatic repulsion between like-charged particles, detailed further in the Supplementary Materials, although nanoscale heterogeneity in the colloidal interactions may also play a role (49). This observation is consistent with previous findings in 2D media (24)(25)(26)(27)(28)32).…”

“…We use the Parti-Suite framework (59) to examine the interactions between single particles or clusters of particles and the glass beads making up the solid matrix. In this framework, Lagrangian trajectories that explicitly incorporate the forces and torques on particles (49) are simulated in a Happel sphere-in-cell model of the pore space surrounding an individual bead (37). Previous work has established the ability of this framework to quantitatively model particle deposition and erosion from surfaces under the influence of imposed flow (49).…”

“…Prior to particle-bead contact, particle velocity is computed from the action of hydrodynamic forces exerted by the imposed flow, computed using the parameter values given in Table S2. Upon contact with the bead surface, particle movement is dictated by the balance between hydrodynamic and attachment torques (49), computed using the parameter values given in Tables S1 and S2, respectively. The trajectories of multi-particle clusters are treated as larger 4 µm-diameter particles simulated in the same way, but using physico-chemical parameters that describe the relevant colloid-colloid interactions.…”

“…For PS, v 1 (Poisson's ratio) and E 1 (Young's modulus) are 0.348 and 4 GPa (70), respectively, and thus, K = 3.03 × 10 9 N/m 2 for for PS-PS. Heterodomains are nanoscale surface heterogeneity wherein net repulsion is reversed to net attraction when a nanoscale heterodomain occupies a critical fraction of the zone of colloid-bead interaction (ZOI) (49). Heterodomain radius (R ZOI ) is calculated from R ZOI = a 2 cont + 2κ −1 r 2 p − a 2 cont , where κ −1 and r p are the Debye length and particle radius, respectively, and a cont = .…”

Colloid transport through soil and other porous media under transient flow conditions—A review

“…It has been found that colloid transport and retention in porous media are generally governed by advection, dispersion, and inactivation, as well as by colloid interactions with various interfaces (Keswick & Gerba, 1980; Schijven & Hassanizadeh, 2000). Based on years of research, it is widely accepted that due to their small size, colloidal suspensions moving through porous media are excluded from pores through which they physically cannot fit (i.e., straining; Bradford & Bettahar, 2005), they have limited diffusivity (James, Wang, & Chrysikopoulos, 2018; Soto‐Gómez, Perez‐Rodriguez, Vazquez Juiz, Lopez‐Periago, & Paradelo Perez, 2019; Yu et al, 2019), and are generally electrostatically repelled from like‐charged porous media surfaces (Johnson, Rasmuson, Pazmino, & Hilpert, 2018; Rasmuson, VanNess, Ron, & Johnson, 2019; VanNess, Rasmuson, Ron, & Johnson, 2019). Because of these features, their transport is both enhanced and impeded in the subsurface, compared to non‐sorbing solutes (Bradford, Šimůnek, Bettahar, van Genuchten, & Yates, 2003; McCarthy & Zachara, 1989; McDowell‐Boyer, Hunt, & Sitar, 1986).…”