Pervaporation performance and characterization of hydrophilic ZSM-5 zeolite membranes for high inorganic acid and inorganic salts

The hydrophilic ZSM-5 zeolite membranes are applied to separate the inorganic acid solutions and inorganic acid/inorganic salt mixtures by pervaporation, and the membrane presents good stability, dehydration and desalination performance. Influences of inorganic acid type (H2SO4, H3PO4, HNO3 and HCl), H2SO4 concentration (1–6 mol·L–1), test temperature (60–90 °C) and inorganic acid/inorganic salt type (2 M H2SO4 and sulfate, 2 M H3PO4 and phosphate) on the pervaporation performance are investigated in this work. Either for concentrating 3% (mass) H2SO4 solution or consecutive dehydrating 20% (mass) H2SO4 solution, the hydrophilic ZSM-5 zeolite membrane has a good dehydration performance and stability. Even though the H2SO4 concentration and test temperature are increased to 6 M and 90 °C, only H2O molecules could pass through the membrane and pH value of the permeation is kept neutral. Besides, the membrane has good dehydration and desalination performance for H2SO4/sulfates and H3PO4/phosphate mixtures, the rejection of natrium salt, molysite, and magnesium are almost 100 %.