A model for the adsorption process of water dissolved elements flowing into reactive porous media: Characterization and sizing of water mining/filtering systems

This study presents a mathematical model describing the adsorption-desorption process of water dissolved elements onto reactive porous materials during filtering operations performed under dynamic flow conditions. The developed model is based on a reversible second order adsorption kinetic featuring the progressive reduction of the purifying capacity of the filtering material due to the gradual exhaustion of the active sites available for solute retention. It enables the simulation of the performances of water filtering systems through the use of parameters having a clear chemical-physical significance or it can be used for the estimation of these parameters to characterize the adsorption properties of the reactive material. Starting from the same adsorptive conceptual model used for the filtering system marked by ongoing flowing conditions, an adaptation for static systems was performed on the mathematical framework in order to process the same chemical physical parameters in both schemes. Adsorption laboratory tests were carried out to validate the developed model. Results show that the kinetic constants and adsorption capacities (a maximum of about 45 mg g^-1 was obtained for the tested material) are highly comparable, both within the same experimental system, and between different experimental setup. This confirms the validity of the developed model which is able to perfectly fit the observed concentration data in all tested configurations.