Modeling Total Organic Carbon Variation in a Photocatalytic Process via Stochastic Differential Equations

Abstract

Advanced oxidative processes (AOP) are an important alternative in the treatment of industrial effluents. Several studies in the literature report that the kinetic profile of organic matter oxidation presents behavior typical of pseudo-first-order reactions. Recent work indicates a conversion rate in two phases: (1) a rapid initial phase described in pseudo-first-order kinetics and (2) a decelerated phase described as pseudo-first order. Previously published work proposed an empirical stochastic model that reproduced these behaviors. In the present study, we found the average conversion degradation calculated by the stochastic model can approximate this dual-reaction rate behavior. This model thus presents a method for estimating the apparent kinetics constant from the model parameters without the need to arbitrarily separate the two conversion stages in the same oxidation process. Additionally, the model's capability to describe the conversion of organic load for different types of effluents and processes showed that this model satisfactorily describes total organic carbon conversion for three different waste (leachate, dairy, and a synthetic one involving benzoic acid) handled by different AOP. Thus, this work evidenced that the proposed model can describe diversified oxidation processes combined with the carbonaceous charge degradation contained in complex industrial effluents.