Rapid spectrophotometric determination of peroxydisulfate in water via oxidative coloration of 2,2′azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) using ferrous ion as catalyst

Abstract

In this study, a rapid, sensitive and reliable spectrophotometric method for peroxydisulfate (PDS) determination in water was established. The proposed spectrophotometric method was based on the oxidation of 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) to form stable and green-colored ABTS radical (ABTS•+) by ferrous ion (Fe(II))-catalyzed PDS. The formed ABTS•+ performed well linear relationship with PDS concentration (R2 > 0.999) in the range of 0–60 μM at four wavelengths of 415, 650, 732, and 820 nm under optimized conditions. The proposed Fe(II)-ABTS spectrophotometric method was highly sensitive with the absorptivity of 3.595 × 104 M−1 cm−1, 1.530 × 104 M−1 cm−1, 1.945 × 104 M−1 cm−1 and 1.768 × 104 M−1 cm−1 at four detection peaks of 415, 650, 732 and 820 nm, respectively. Additionally, the proposed Fe(II)-ABTS spectrophotometric method possessed well anti-interference capacity to common natural water constituents and was reliable to determine PDS concentration in water. What’s more, the proposed Fe(II)-ABTS spectrophotometric method was successfully applied in monitoring the change of PDS concentration during the degradation of diclofenac in heat-activated PDS process. In a word, the proposed Fe(II)-ABTS spectrophotometric method could be employed as a promising approach for the rapid and accurate measurement of PDS in water, and this study provided a new perspective for the measurement of PDS by the visible spectrophotometry.