Photochemical Degradation of Aqueous Artificial Sweeteners by UV/H2O2 and Their Biodegradability Studies

Ramtin Jahani

doi:10.32920/ryerson.14644884.v1

Abstract

<p>In this study, the photochemical degradations of three commonly used artificial sweeteners, namely aspartame (ASP), acesulfame K (ACE), and sucralose (SUC) were investigated in multicomponent aqueous systems through UV/H2O2. A recirculating batch photochemical reactor setup was utilized for experimental work. The treatability of the multicomponent system was monitored in the form of total organic carbon (TOC) reduction. A two-level fractional factorial design of experiments (DOE) was adopted. The individual and multifactor interaction effects of the concentration of the three sweeteners, the applied hydrogen peroxide dosage and the operating temperature on TOC reduction were investigated. The biodegradability characteristics of the sweeteners were investigated for both single and multicomponent systems through respirometry. Their degradations were compared to those of the UV/H2O2 system. It was determined that the UV/H2O2 process is suitable treatment technique, achieving TOC removal efficiencies over 90% with a UV exposure of 45 min. The operating temperature and the applied H2O2 dosing on the final TOC removal were found to be significant. An interaction between ASP and SUC resulted in a temporary improvement in TOC removal midway through the treatment process. Respirometric studies confirmed that ACE and SUC are non-biodegradable. The biodegradation characteristics of ASP was found to be acceptable with a 6-day biochemical to theoretical oxygen demand (BOD6/ThOD) ratio of 0.63±0.02.</p>

Highlights

In 2009, the occurrence of the artificial sweetener acesulfame K (ACE) in the aquatic environment was highlighted for the first time (Buerge et al, 2009)
The degradation of ASP was studied for the first time under UV irradiation (λ≅254 nm) alone and in a UV/H2O2 system
Under UV irradiation alone (λ≅254 nm), the appearance of colour in the sample indicated a phototransformation of the parent compound but resulted in no significant total organic carbon (TOC) reduction

Summary

Introduction

In 2009, the occurrence of the artificial sweetener ACE in the aquatic environment was highlighted for the first time (Buerge et al, 2009). The presence of seven artificial sweeteners in German water, wastewater and soil samples were reported (Buerge et al, 2009; Scheurer et al, 2009). The results were used to design experiments (by statistical means) to investigate the behaviour of a multicomponent aqueous system containing ASP, ACE and SUC in the same matrix. Respirometric studies were carried out to screen for the degradation of each sweetener in the presence of activated sludge both in individual and multicomponent systems. The experimental results of the treatment of artificial sweeteners through UV/H2O2 in both individual and multicomponent systems are discussed. The primary focus of the preliminary experiments was to investigate how well ASP, ACE and SUC respond to treatment under UV irradiation alone and UV irradiation in the presence of varying doses of H2O2.

Objectives

Methods

Results

Discussion

Conclusion