Kinetic Modeling of Photodegradation of Water-Soluble Polymers in Batch Photochemical Reactor

Abstract

Synthetic water-soluble polymers, well-known refractory pollutants, are abundant in wastewater effluents since they are extensively used in industry in a wide range of applications. These polymers can be effectively degraded by advanced oxidation processes (AOPs). This entry thoroughly covers the development of the photochemical kinetic model of the polyvinyl alcohol (PVA) degradation in UV/ H 2 O 2 advanced oxidation batch process that describes the disintegration of the polymer chains in which the statistical moment approach is considered. The reaction mechanism used to describe the photo-degradation of polymers comprises photolysis, polymer chain scission, and mineralization reactions. The impact of operating conditions on the process performance is evaluated. Characterization of the polymer average molecular weights, total organic carbon, and hydrogen peroxide concentrations as essential factors in developing a reliable photochemical model of the UV/H 2 O 2 process is discussed. The statistical moment approach is applied to model the molar population balance of live and dead polymer chains taking into account the probabilistic chain scissions of the polymer. The photochemical kinetic model provides a comprehensive understanding of the impact of the design and operational variables.

Nonlinear System Identification for Aqueous PVA Degradation in a Continuous UV/H2O2 Tubular Photoreactor

“…This confirms those results found by Hamad et al 26 in our previous study. The TOC removal dropped after a maximum rate, most likely due to the scavenging effect of H 2 O 2 on HO • , as described by Hamad et al 28 in the following reaction…”

“…In previous studies, the application of the UV/H 2 O 2 processes for the PVA degradation was typically focused on the pollutant (TOC content) removal, H 2 O 2 residuals, average molecular weight reduction, and the effluent pH in representing PVA degradation efficiencies, H 2 O 2 utilization, and acidic/low-molecular-weight intermediate formation. 5,28,29 The results varied under various H 2 O 2 dosages and influent PVA concentrations, with an optimum operating point at a H 2 O 2 /PVA mass ratio of 1.0 at the influent stream. 13,25 More importantly, the formation of intermediates during PVA degradation was proven by a decrease in the average molecular weight of pollutants throughout a batch degradation measured by gas permeation chromatography (GPC) analyses and a decrease in pH in the aqueous system.…”

“…5,13,26−28 The decrease in pH further indicated the formation of acidic intermediate throughout the batch PVA degradation process. 28 Hence, in this study, the H 2 O 2 dosage was utilized as the manipulating variable to investigate its effects on TOC removal, effluent pH, and the quality of effluent in terms of H 2 O 2 residuals under steady-state and transient conditions. In the experimental setup shown in Figure 1, the process input is characterized by inlet H 2 O 2 concentration, while the process outputs are characterized by the total organic carbon removal, the H 2 O 2 residual, and the effluent pH.…”

Studying the Effect of Magnesium Oxide Nanoparticles Prepared on the Surface of Poly Methyl Methacrylate

“…This corresponds to the other times of the irradiation for polymeric films. The increase with the increased absorption of polymeric films to UV radiation during the irradiation process and the values of the coefficient of absorption of the hydroxyl group (I OH ) increased the speed of disintegration of optical oxidation of polymer films (34).…”

ARX-PID/NARX-PID Modelling and Control of UV/H2O2 Tubular Photoreactor for PVA Degradation in Water

“…Though used as a leading method for degradation of organic pollutants, biological treatment can only treat wastewater that is readily degradable by living organisms. If that is not possible, researchers mainly focused on the oxidation of polyvinyl alcohol (PVA) in an Advanced Oxidation Process (AOP) such as UV/H2O2 process as an easy process owing to its relatively developed kinetics, non-selective degradation, low cost, and ease in operation at large-scale [1][2][3]. In particular, the UV/H2O2 process requires modelling to establish a control system that prevents adverse effects of PVA and residual hydrogen peroxide (H2O2) to the aquatic system and subsequent biological processes by maintaining H2O2 residuals in the treated effluent within a safe level.…”