Theoretical and Practical Basis of the Regeneration and Disposal of Sulfuric Copper Etching Solutions Used in the Production of Printed Circuit Boards by Membrane and Membraneless Electrolysis

Abstract

Abstract An electrochemical method for the neutralization, disposal, and regeneration of sulfuric acid solutions of copper etching used in the production of printed circuit boards has been proposed. The possibility of the electrochemical regeneration of sulfuric acid solutions of a copper etching containing H 2 O 2 or $${{{\\text{S}}}_{{\\text{2}}}}{\\text{O}}_{{\\text{8}}}^{{{\\text{2}} - }}$$ oxidizer is investigated. Membraneless electrolysis is suitable exclusively for the disposal of spent solutions by removing residues of the H 2 O 2 or $${{{\\text{S}}}_{{\\text{2}}}}{\\text{O}}_{{\\text{8}}}^{{{\\text{2}} - }}$$ oxidizing agents and toxic Cu 2+ from spent solutions with a minimum power consumption of 3.88 (kW h)/(kg Cu). The possibilities of membrane electrolysis in a two-chamber cell are limited by the removal of Cu 2+ and with the possibility of creating conditions for the synthesis of $${{{\\text{S}}}_{{\\text{2}}}}{\\text{O}}_{{\\text{8}}}^{{{\\text{2}} - }},$$ while the regeneration of the H 2 O 2 oxidant is impossible. Electrolysis in a three-chamber cell with two ion-exchange membranes has great functionality, as it allows one to simultaneously remove Cu 2+ with a fraction of the current carried by Cu 2+ up to 9.7%, preserve the H 2 O 2 oxidizer, or synthesize a $${{{\\text{S}}}_{{\\text{2}}}}{\\text{O}}_{{\\text{8}}}^{{{\\text{2}} - }}$$ oxidizer with a current efficiency of up to 42.6% (in the absence of special additives).