Overlooked Significance of Chromium(V) and Chromium(IV) in Environmental Chemistry and Influence of Peroxyacetic Acid on Chromium in Wastewater

Abstract

Chromium (Cr) redox chemistry in the environment occurs through intermediate species penta-valent Cr (Cr(V)) and tetra-valent Cr (Cr(IV)) which are highly reactive. Environmental literature lacks substantial information on Cr(V) and Cr(IV) species in various redox processes. A perspective is first presented on the aquatic chemistry of Cr(V) and Cr(IV) and their behavior under different environmental conditions. Following this, Cr-intermediate species were investigated in the reaction between Cr and peroxyacetic acid (PAA). Transition metal ions have been used to activate the disinfectant PAA for improved degradation of organic contaminants. The potential of Cr(III) already existing in water may react with PAA, producing radical species and Cr-intermediates that can oxidize coexisting contaminants in water. This research finds enhanced degradation of trimethoprim (TMP) and other pharmaceuticals from PAA-Cr(III) in basic pH. Reactive species present in this system are explored and implications of Cr(IV) and Cr(V) for future pollutant degradation are discussed.