Nano-enhanced Dialytic Fluid Purification: CFD Modeling of Pb(II) Removal by Manganese Oxide.

Nano-enhanced dialytic fluid purification is an evolution of biomedical dialysis that has been proposed as a novel method for applying nanomaterials in water treatment. Using nanosized hexagonal birnessite (δ-MnO2) in a simplified dialytic system, we demonstrate herein an almost complete removal (98%) of Pb(II) within 3 h of treatment while monitoring environmental variables pH and Eh (redox potential). A mathematical model of the purification process is constructed in COMSOL Multiphysics to demonstrate how nanoadsorption using free-flowing nanoparticles in a dialytic system can be studied theoretically using computational fluid dynamics (CFD). The CFD model closely agrees with experimental results, estimating a 95% removal over 3 h of treatment and suggesting an 18% consumption of available adsorbent capacity. Additional insights into the progress and mechanisms of the adsorption process are also revealed. Finally, the nanoenhanced model is compared against standard dialysis absent of nanomaterials using COMSOL, and key differences in removal efficiency are highlighted. Results indicate that nanoenhanced dialysis can attain almost complete removal in 3 h of treatment or reach the same removal goal as standard dialysis in less than two-third of the treatment time.