Mn electrowinning in a diaphragm cell: Mn2+ + 2e- to Mn at stainless cathodes competes with hydrogen evolution; Pb-Ag anodes evolve oxygen.
m = eta I t M / (n F), n = 2, M = 54.94 g/mol
V = 2.7 + j (d / kappa + R_diaphragm) + overpotentials
eta = 0.70 - f(pH - 7.2) - f(T - 38) - f(SeO2 - 40) + f(j)
E = 2 F V / (eta M) = 976 V / eta kWh/t
Out-of-window pH or no selenium makes H2 evolve, cuts current efficiency and gives brittle flaking deposit. Click a cathode to strip (harvest) it once it is thick enough.