NITRIC ACID CONCENTRATION MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To rapidly and accurately measure the concn. of nitric acid in a soln. to be measured and perform measurement on-line even in a biological nitration or denitrification process. SOLUTION: The soln. to be measured in the nitration or denitrification process of a nitration and denitrification reaction tank 2 is introduced into a measuring tank 11 and the soln. in the tank 11 is circulated by a pump P2 through a circulating passage 2 to be held to an anaerobic state and a substrate such as methanol is added to the soln. to be measured from a substrate introducing passage 15 to perform biological denitrification reaction and the ORP signal detected by an ORP meter 16 is inputted to an operation device 17 and the concn. of nitric acid is operated from the addition amt. of the substrate up to a point of time when the ORP value falls suddenly.