Prediction of arsenic breakthrough in a pilot column of polymer-supported nanoparticles

Adsorption is an important process for arsenic removal from drinking water supplies. Fixed bed column processes are the preferred mode of operation owing to their simplicity and proven performance. Mathematical models can facilitate the design and optimization of fixed bed adsorbers. For systems exhibiting linear isotherm behavior over the relevant concentration range, their performance can be predicted using models that are amenable to analytical solutions. The predictive utility of an asymptotic solution of the homogeneous surface diffusion model (HSDM) and an approximate solution of a linear driving force model (LDFM) under linear isotherm approximation was evaluated in this study. A previously published pilot test on arsenic breakthrough in a fixed bed adsorber of polymer-supported nanoparticles was modeled. Model parameters were estimated on the basis of some easily determined batch measurements. The pilot test yielded 27,000 bed volumes at 10 μg/L arsenic. The two analytical solutions predicted 24,200 and 27,100 bed volumes. Despite the simplicity of the HSDM and LDFM solutions, their predictions agreed well with the experimental data. These analytical solutions are very straightforward, easy to apply, and provide acceptable modeling power.