The variation of relative ion percentage removal with membrane fixed charges concentration in the diluate channel of the spacer-free cell for feed Is = 593 mol/m3, ϕw,CEM = 0.5 Lw/Lsp, and ϕw,AEM = 0.4 Lw/Lsp. () cF,CEM = 1600 mol/m3 and cF,AEM = 1809 mol/m3 at L = 2 cm and V = 0.3 V, () cF,CEM = 2400 mol/m3 and cF,AEM = 2689 mol/m3 at L = 2 cm and V = 0.3 V, () cF,CEM = 3210 mol/m3 and cF,AEM = 3580 mol/m3 at L = 2 cm and V = 0.3 V, () cF,CEM = 1600 mol/m3 and cF,AEM = 1809 mol/m3 at L = 10 cm and V = 1.3 V, () cF,CEM = 2400 mol/m3 and cF,AEM = 2689 mol/m3 at L = 10 cm and V = 1.3 V, () cF,CEM = 3210 mol/m3 and cF,AEM = 3580 mol/m3 at L = 10 cm and V = 1.3 V.