Simple and Rapid Determination of Boron in the Wastewater with Azomethine H Using Accelerating Effect of Ammonium Ion

Abstract

Boron is widely used in industry, and is regulated by the effluent standard (10 mg/L) in Japan. The standard azomethine H absorptiometric method for determining boron concentration requires long time; therefore, we have developed a simple, rapid azomethine H method for the management of the wastewater treatment equipment. The amount of boron was determined by measuring the absorbance of the boron-azomethine H complex after 5 min by using a simple spectrophotometer with a photodiode (370-600 nm) and a light-emitting diode (470 nm). Phosphate buffer with ammonium chloride was used, because the ammonium salt accelerated the formation of the boron complex. The effect of a large amount of calcium ions in the wastewater, which originated from calcium hydroxide, was eliminated by adding an excess of the buffer reagents. A combination of powdered azomethine H, L-ascorbic acid, EDTA, potassium dihydrogenphosphate, disodium hydrogenphosphate, and ammonium chloride was appropriate for the simple, rapid on-site determination of boron using a portable spectrophotometer.