Abstract
Photo-induced Advanced Oxidation Processes (AOPs) using H2O2 or S2O82− as radical precursors were assessed for the abatement of six different contaminants of emerging concern (CECs). In order to increase the efficiency of these AOPs at a wider pH range, the catechol organic functional compound was studied as a potential assistant in photo-driven iron-based processes. Different salinity regimes were also studied (in terms of Cl− concentration), namely low salt water (1 g·L−1) or a salt–water (30 g·L−1) matrix. Results obtained revealed that the presence of catechol could efficiently assist the photo-Fenton system and partly promote the photo-induced S2O82− system, which was highly dependent on salinity. Regarding the behavior of individual CECs, the photo-Fenton reaction was able to enhance the degradation of all six CECs, meanwhile the S2O82−-based process showed a moderate enhancement for acetaminophen, amoxicillin or clofibric acid. Finally, a response-surface methodology was employed to determine the effect of pH and catechol concentration on the different photo-driven processes. Catechol was removed during the degradation process. According to the results obtained, the presence of catechol in organic macromolecules can bring some advantages in water treatment for either freshwater (wastewater) or seawater (maritime or aquaculture industry).
Highlights
Fenton-based processes are among the most promising Advanced Oxidation Processes (AOPs) for water detoxification and, for the abatement of Contaminants of Emerging Concern (CECs), for which conventional treatment methods are poorly effective [1]
The main goal of this study is to investigate catechol as a possible assistant in photo-driven iron-based processes for water treatment, namely the photoFenton process, i.e., H2 O2 -based, or persulfate (PDS; S2 O8 2− -based) process
In the case of group iron reduction into Fe (II) compounds, the addition of CAT can promote the efficiency of the PDS-based system in both low salt water (LSW) and SW, which means that the time to reach 50% of degradation is reduced by approximately half in the presence of CAT in solution
Summary
Fenton-based processes are among the most promising Advanced Oxidation Processes (AOPs) for water detoxification and, for the abatement of Contaminants of Emerging Concern (CECs), for which conventional treatment methods are poorly effective [1]. The use of organic ligands able to form photoactive compounds with Fe(III) has been examined, using different substances for this purpose such as oxalate, citrate, EDTA or EDDS [9,11,12] Since they have to be added to the solution, their biodegradability and/or potential toxicity are key factors for their use in water treatment systems. Searching for naturally occurring substances to be used as chemical auxiliaries for photo-Fenton processes has received scientific interest
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