Hi,

electrolysis with platine of H2SO4(30%) 12V 0.7A

let's do this for 48hours with 50mL of 30% H2SO4 (d=1.26, 18,9g(0.2mol) of H2SO4 and 44.1g (3mol H2O)

to simplify let's say that all the H2O will disapear first, then the H2S2O8, and no H2SO5 will be formed

H2O --> H2 + 1/2 O2 at 0.25mol/h 24hours are needed

then 2 H2SO4 --> H2S2O8 + H2 at 0.25mol/h 2hours are needed...

i guees if some H2O2 is formed (H2S2O8 + 2H2O --> 2 H2SO4 + H2O2) it will disapear (H2O2 --> H2 + O2)

and after 30 hours we would get pure H2SO4 by adding good amount of H2O and NaCl...

i try now i'll tell you the results (how many ml obtained, intensity compared to time and problems or not to keep the solution cold, mixing every hour)