New Mechanistic Based Correlation Equation for Predicting Colloid Attachment Efficiency: Traditional vs. Discrete Heterogeneity Approaches
Tuesday, 16 December 2014: 3:20 PM
In this work we present a correlation equation that predicts colloid attachment efficiency over soda-lime glass collectors. We review the traditional attachment efficiency approaches, which are based on packed column experiments and mean field parameters that define the colloid-collector interactions, and contrast them with a discrete heterogeneity approach. This new correlation equation was developed to capture prediction from a trajectory model that quantitatively explains directly observed colloid retention in an impinging jet system under unfavorable conditions via incorporation of discrete zones of attraction (nanoscale heterodomains). In order compare of observed and simulated retention in the impinging jet with granular porous media, we developed a linkage between the jet and Happel sphere unit-cell geometries. We demonstrate that attachment efficiency can be mechanistically explained by near surface trajectory analysis and well represented by three terms: 1) Maxwell distribution of colloids in the near surface fluid domain, 2) Spacing and size distribution of heterodomains on the collector relative to colloid size, and 3) Torque and force balance of the colloid in contact with heterodomains. These results indicate that a traditional empirical approach can be improved to a theoretical framework that, from basic principles, is able to predict colloid retention under unfavorable conditions.