•The erosion effects of HCl-FeCl2 was investigated on anion exchange membranes.•Organic solution containing HCl/glyphosate was firstly separated through DD process.•QPPO/PVA membranes have higher DD performances than commercial membranes.Diffusion dialysis (DD) is a process that the solutes pass through the ion exchange membrane from the feed side to water side. Some solutes such as HCl–FeCl2 may be erosive on membrane structure during practical DD process. The erosion effects are investigated by four anion exchange membranes, including commercial membranes DF-120 and 9010, and our previous membranes based on quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) and polyvinyl alcohol (PVA). Besides, the membranes are also used to separate organic solution containing HCl and glyphosate, which is produced largely during the preparation of glyphosate pesticide.The membrane structures are damaged and their performances are reduced after the erosion of HCl–FeCl2, which are mainly attributed to the loss of –N+(CH3)3Br− and –OH groups. The weight loss percent is in the range of 10–21%, the ion exchange capacity decreases but the swelling degree increases. The dialysis coefficient of HCl (UH-1) and separation factor (S1) reduce to 0.006–0.010 m h−1 and 13.9–15.5 for commercial membranes, and 0.016–0.024 m h−1 and 33.2–47.6 for QPPO/PVA membranes, correspondingly. Besides, the membranes without erosion are used to separate organic solution containing HCl and glyphosate. The UH-2 is in the range of 0.0040–0.0062 m h−1 for commercial membranes, and 0.0094–0.0104 m h−1 for QPPO/PVA membranes. The UH-2 values are generally stable within 10 h, and the acid concentration in the feed side decreases from 5.82 to 3.16 mol L−1. Hence, the QPPO/PVA membranes can be potentially applied in DD process to recover acid from organic solution containing HCl and glyphosate.

•PVA- or SPPO-based hybrid membranes containing UHPS are prepared.•UHPS is proposed for the first time as alkali transport promoter in hybrid membranes.•UOH are 0.01–0.022 m/h, about 2–5 times higher than blank membranes.•The “trade-off” effect between ions permeability and selectivity is broken.Alkali transport promoter is designed from 3-(ureidoarene)propyltriethoxysilane (UPTS), which takes sol–gel process to form ureidoarene–heteropolysiloxane (UHPS) within polyvinyl alcohol (PVA). Hence PVA-based hybrid membranes are obtained for diffusion dialysis (DD) application. Besides, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) is used as reference to compare the formation of alkali transport promoter within different polymer matrix.The micro-aggregation of UHPS within PVA leads to loose structure, while within SPPO leads to plenty of clusters within 0.1–0.5 μm. The membrane swelling resistance is improved but the alkaline stability is reduced in the presence of UHPS. The PVA-based membranes have the tensile strength (TS) of 19–52 MPa, and the elongation at break (Eb) of 343–534%. DD results show that the dialysis coefficients of OH− (UOH) are in the range of 0.01–0.022 m/h in the presence of UHPS, which are about 2–5 times higher than the blank PVA or SPPO membranes. The separation factors (S) are in the range of 26–32, which are also higher than the blank membranes. Hence, UHPS can act as alkali transport promoter for DD process. The effect of UHPS is affected by the membrane matrix and micro-aggregation degree.