Iohexol degradation in wastewater and urine by UV-based Advanced Oxidation Processes (AOPs): Process modeling and by-products identification

Abstract

In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/HO, UV/HO/Fe). Water, wastewater and urine were spiked with Iohexol, in order to investigate the treatment efficiency of AOPs. A tri-level approach has been deployed to assess the UV-based AOPs efficacy. The treatment was heavily influenced by the UV transmittance and the organics content of the matrix, as dilution and acidification improved the degradation but iron/HO increase only moderately. Furthermore, optimization of the treatment conditions, as well as modeling of the degradation was performed, by step-wise constructed quadratic or product models, and determination of the optimal operational regions was achieved through desirability functions. Finally, global chemical parameters (COD, TOC and UV-Vis absorbance) were followed in parallel with specific analyses to elucidate the degradation process of Iohexol by UV-based AOPs. Through HPLC/MS analysis the degradation pathway and the effects the operational parameters were monitored, thus attributing the pathways the respective modifications. The addition of iron in the UV/HO process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix.

Control of optical transparency and infrared laser heating of costal cartilage via injection of iohexol

“…Iodinated contrast media are photo‐sensitive molecules decomposing under certain conditions to iodine and byproducts. Therefore, iohexol stability under IR laser radiation was investigated.…”

“…Raman spectra were measured immediately after irradiation. The common byproduct of iohexol decomposition is molecular iodine , therefore its formation under laser irradiation was checked by addition of 1:10 mass ratio of starch immediately after irradiation due to its ability to form colored complex with iodine. The nature of anomalous high intensity of 170 cm −1 band of iohexol was investigated by adding 0.012 g/mL of sodium thiosulfate Na 2 S 2 O 3 , which is known to reduce free iodine to I − in a quick and quantitative manner. The influence of molecular iodine presence on iohexol spectral properties was analyzed separately by adding 0.044 g/mL of molecular iodine to untreated iohexol solution.…”

Insights into the Photocatalytic Bacterial Inactivation by Flower-Like Bi2WO6 under Solar or Visible Light, Through in Situ Monitoring and Determination of Reactive Oxygen Species (ROS)

“…Over the last few decades, environmental contamination has shifted from the exclusive focus of organic and inorganic pollutants [1], towards the inclusion of bacteria and other organisms [2][3][4]. Therefore, well-organized methods are urgently required to control the spread [5] or eradicate microorganism-related issues [6].…”

Light-Assisted Advanced Oxidation Processes for the Elimination of Chemical and Microbiological Pollution of Wastewaters in Developed and Developing Countries

“…Enhancing its action with H 2 O 2 and by the production of HO • , did not significantly enhance the degradation kinetics, however moderately reduced the TOC of the solution, thus removing some of the recalcitrant intermediates. Similarly, adding iron to enhance the action of UV/H 2 O 2 by the parallel UV-Fenton process only slightly enhanced the degradation kinetics, however the analysis of the intermediates revealed pathways that were not achieved during the degradation of the parent compound by UVC alone [ 89 ].…”