Donnan dialysis-based approach for reclamation of waste acid with a low concentration

This study provides a proof-of-concept investigation into the direct utilization of low-concentration recovered acid as a proton source for the efficient recovery of organic acids via Donnan dialysis, a scenario of particular significance in industrial parks. A primary objective is to examine the implications of waste acid concentration on the coupling process. To evaluate the technological feasibility, process simulations are performed utilizing a mathematical model grounded in the Nernst-Planck equation and associated equilibrium relationships. Furthermore, a variety of experimental conditions, encompassing different types of organic acids and varying concentrations of waste acid, are explored to analyze the ion substitution behaviors involved. The findings from both simulations and experiments indicate that weaker organic acids demonstrate superior performance, particularly regarding recovery rates and process efficiency. Additionally, it is revealed that merely increasing the concentration of the draw solution does not constitute an effective approach for improving the DD-based organic acid recovery process, thereby suggesting the potential for the direct application of low-concentration recovered acid. Given its significant advantages, the proposed DD-based coupling technology shows considerable promise for future applications.