Activation of Hydrogen Peroxide and Solid Peroxide Reagents by Phosphate Ion in Alkaline Solution

Abstract

Abstract Hydrogen peroxide (HP) and its derivatives can serve as useful bulk oxidants for soil and water treatment provided activation is supplied. Solutions of a model compound methylene blue (MB) were treated with HP, urea hydrogen peroxide (UHP), sodium perborate (SPB), sodium percarbonate (SPC), or calcium peroxide (CP). In unbuffered systems, addition of HP or UHP was ineffective in decolorizing MB, whereas addition of SPB or SPC was moderately effective due to the known ability of borate or carbonate ions, respectively, to activate H2O2. Addition of CP caused moderate decolorization as well, but base hydrolysis contributed due to the high pH (∼12). Decolorization of MB in HP, UHP, SPB, and SPC systems was greatly accelerated when mixtures were buffered at pH 10 with phosphate (25 mM) compared to mixtures where pH was unadjusted, NaOH adjusted, or carbonate adjusted. Decolorization correlated strongly with decomposition of active peroxide (AP), implying a shared pathway. Decolorization was highly ine...