A Simple and Rapid Determination Method of Boron in Wastewater Using Ion-Selective Electrode

Abstract

A simple and rapid determination method of boron concentration in wastewater using an ion-selective electrode has been developed. By adding H₂SO₄and HF to a H3BO₃ solution, H₃BO₃is converted to BF₄^-, which can be measured with a commercial BF₄^-ion-selective electrode. The BF₄^-formation rate obeys the first-order kinetics with respect to the H₃BO₃ concentration. Approximately 1 hour is usually required for the complete conversion of H₃BO₃to BF₄^-. The authors found that by applying the rate equation to a BF₄^-profile in the initial 10 min of the reaction, the original boron concentration in wastewater can be determined from the curve fitting, which leads to a considerable reduction in the measurement time. They also found that NaF can replace toxic HF as a fluorine source in the determination. The proposed method can detect a range of 1-300 mg-B dm^-3without any pretreatments; this range covers the Japanese wastewater standards for boron.