The Influence Of Temperature And Organic Matter On The Decomposition Kinetics Of Peracetic Acid In Aqueous Solutions

Abstract

Peracetic acid (PAA) is a powerful sanitizer used by food industries all over the world. The main disadvantage of PAA is its decomposition rate. The main purpose of this paper is to study the decomposition of PAA between 20 and 40 C with 0.0, 2.5 or 5.0 g.L-1 of beer, milk or tomato juice in its solutions. The observed decomposition of PAA is a first-order reaction for solutions free of organic matter with observed rate constants from 1.24.10(-3) to 5.59.10(-3).h(-1) and an activation energy (E-a) of 62.11 kJ.mol(-1). However a pseudo first-order reaction was observed in the presence of organic matter and the rate constants between 1.13.10(-3) and 2.18.10(-2) h(-1). The E-a calculated by the observed decomposition rate constants are 42.3 and 61.2 kJ.mol(-1) when there was 2.5 and 5.0 g/L beer in solution, respectively. PAA solutions contaminated with 2.5 and 5.0 g.L-1 milk have showed E. values between 9.7 and 55.3 kJ.mol(-1), respectively. For tomato juice solutions, the Arrhenius equation slope was not constant. The different E. obtained indicate that different mechanisms are taking place at the various tested operating conditions. This work also proposes a mathematical equation to estimate the PAA concentration for solutions free of organic matter.