Abstract: The present invention relates to an apparatus to produce oxidizing agent-rich sulfuric acid by electrolysis of sulfuric acid. More specifically, it relates to the apparatus by which dilute sulfuric acid of the specified temperature and concentration is formed within the electrolysis system and then, by electrolysis of the formed dilute sulfuric acid, electrolytic sulfuric acid containing richly oxidizing agent is formed at a high efficiency and safely under the temperature control.

Abstract: Provided are: a method of measuring the total concentration of oxidizing agents, by which the total concentration can be determined in a single measurement with simple operations even in an evaluation solution containing multiple components such as persulfuric acid, perosulfate and hydrogen peroxide; a simple and inexpensive concentration meter for measuring the total concentration of oxidizing agents; and a sulfuric acid electrolysis device comprising the concentration meter. The method according to the present invention is a method of measuring the total concentration of oxidizing agent(s) in an evaluation solution containing at least one oxidizing agent. The method comprises at least the steps of: heat-treating the evaluation solution at 50 to 135° C.; and detecting hydrogen peroxide in the thus heat-treated evaluation solution.

Abstract: The present invention provides an electrically conductive diamond electrode comprising an electrically conductive substrate and an electrically conductive diamond layer coated on the surface of the electrically conductive substrate, featuring that: 1) the thickness of the electrically conductive diamond layer is 1˜25 ?m, 2) the potential window fulfills Equation (1) and 3) the ratio (A/B) of the diamond component A and the non-diamond component B by the Raman spectroscopic analysis fulfills Equation (2). 2.1V?potential window?3.5V??(1) 1.5<A/B?6.5??(2) A: Intensity at the wave number 1300 cm?1 by the Raman spectroscopic analysis B: Intensity at the wave number 1500 cm?1 by the Raman spectroscopic analysis.