•CSM/PMMA composite membranes were prepared by radical polymerization.•The composite membranes possessed excellent alkali resistance.•The as-prepared membranes were used for alkali recovery via diffusion dialysis.Cation-exchange membranes for diffusion dialysis (DD) were prepared by selecting chlorosulfonated polyethylene (CSM) and methacrylic acid (MAA) as framework and functional monomer, respectively. An interpenetrating network structure (IPN) was formed by free radical polymerization and consequent crosslinking reaction. The membranes possessed ion exchange capacities (IECs) of 1.98–3.12 mmol/g, water uptake (WR) of 12.7–34.8%, swelling degree of 72.7–170% as well as favorable thermal stability and alkali resistance (almost zero mass loss in hot alkali solution). The membranes were applied for DD process to recover alkali from NaOH/Na2WO4 system at 25 °C and 65 °C. Results indicated that coefficients for OH− (UOH) were in the range of 0.0015–0.018 m/h and separation factors (S) were in the range of 9–33 at 25 and 65 °C, respectively.Download high-res image (77KB)Download full-size image

•Hybrid membranes were prepared by blending SPPO and AMMS.•The as-prepared membranes were used for alkali recovery via diffusion dialysis.•Incorporation of AMMS could improve UOH and S of hybrid membranes simultaneously.Cation exchange membranes (CEMs) aimed at alkali recovery were prepared by incorporation of amino-modified mesoporous silica (AMMS) particles into sulfonated poly (2, 6-dimethyl-1, 4-phenyleneoxide) (SPPO). The as-prepared membranes possess water uptake (WR) of 36–42.1%, swelling degree of 49.7–60.5%, mass loss around 8–16.6%, tensile strength (TS) of 26–30.8 MPa, as well as favorable thermal stability. The samples were investigated in NaOH/Na2WO4 model waste feed solution for alkali recovery via diffusion dialysis (DD) at various temperatures. Results revealed that the hybrid membrane always maintain high values of OH− coefficients and separation factors as well even at 55 °C. Improved performances of hybrid membranes were most likely due to the acid-base pairs between amino and sulfonic acid group and crosslinking between sulfonic acid groups under thermal treatment.