Exploration of the Mechanism of Acid Tailing on Strong-Base Ion Exchangers: Modeling and Experiment

A new DTSD-S model (combining the ion-exclusion chromatography-Donnan model and two-step dissociation of sulfuric acid) was developed herein to predict CP, SO d42- and CP, HSO d(4)- in the resin pores during the adsorption and desorption processes. A comparison of CP, SO d(4)(2)- and CP, HSO d(4)- during the desorption process showed that the tailing phenomenon was affected by the acid concentration. When CH + was lower than 0.9 mol/L, the predominant species in the resin pores was SO42- instead of HSO4-, which verified that the sulfuric acid tailing was caused by SO42 -. The results of energy-dispersive spectroscopy and X-ray photoelectron spectroscopy of the resins after adsorption showed the existence of extra S element, which further verified that the existence of SO(4)(2)was the main factor that caused the acid tailing. Finally, we concluded that the acid tailing was inevitable and suggested that one could recover a high H2SO4 concentration by using a high feed acid concentration.