On the relative Coulombic effectiveness and profitability of electrolysis via intermittent current

The current and energy utilization of intermittent current electrolysis is analysed, and feasibility regions in terms of product costs and profitability are discussed using the deposition of copper as an illustrative example.Nomenclature A electrode area - b geometric aspect ratio,W/L - c₀ bulk electrolyte concentration - C_E Unit price or electricity, including generation of intermittent potential-drop train (MU J^–1) - C_p unit price of electrolysis product (MU kg^–1) - D electrolyte diffusivity - E relative Coulombic effectiveness - F Faraday's constant - h chart recording heights (Fig. 1) - I current - I_m maximum allowable current in d.c. electrolysis - k mass transfer coefficient - L length of straight section in current response (Fig. 1) - MU arbitrary monetary unit - m_e electrochemical coefficient of product (kg C^–1) - n number of electrons involved in cathode reaction - N number of cycles in intermittent potential train - P unit profit (MU kg^–1) - r chart recording height ratio, or corresponding current ratioh₁/h₂=I₁/I₂ - S_I root mean square of deviations about the fitted curve - t time - V_c magnitude of intermittent potential drop (V) - V_m maximum allowable potential drop in d.c. electrolysis (V) - W length of trapezoidal portion in response (c) (Fig. 1) - X potential drop ratioV_c/V_m - Y ratio of unit profits - Z_i functions defined in Equation 9b (Z₁) and Equation 10b (Z₂) - lumped parameter (Equation 4) - chart response angle - half-period of intermittent potential-drop Train