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 C P,SO 4 2– and C P,HSO 4 – in the resin pores during the adsorption and desorption processes. A comparison of C P,SO 4 2– and C P,HSO 4 – during the desorption process showed that the tailing phenomenon was affected by the acid concentration. When C H + was lower than 0.9 mol/L, the predominant species in the resin pores was SO 4 2– instead of HSO 4 –, which verified that the sulfuric acid tailing was caused by SO 4 2– . 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 H 2 SO 4 concentration by using a high feed acid concentration.