Iohexol Degradation Research Articles

Identifying the Role of Oxygen Vacancy on Cobalt-Based Perovskites Towards Peroxymonosulfate Activation for Efficient Iohexol Degradation

Identifying the Role of Oxygen Vacancy on Cobalt-Based Perovskites Towards Peroxymonosulfate Activation for Efficient Iohexol Degradation

Enhanced degradation of iohexol in water by CuFe2O4 activated peroxymonosulfate: Efficiency, mechanism and degradation pathway

Iohexol as an iodinated X-ray contrast agent is widely used, and it is the potential precursor for toxic iodinated disinfection by-products in the disinfection process. In this study, a series of CuFe2O4 catalysts were prepared by sol-gel method with different molar ratios of total metal cations to citric acid ([Men+]T/CA) and employed as heterogeneous catalysts to activate peroxymonosulfate (PMS) for the removal of iohexol. The catalysts were characterized by various technologies, and the effect of [Men+]T/CA molar ratio on the catalysts' properties was explored. The CuFe2O4 synthesized with [Men+]T/CA molar ratio of 1:1 showed the best catalytic activity to PMS, and 95.0% of 1.0 mg/L iohexol was removed within 15 min by using 50 mg/L CuFe2O4 and 20 mg/L PMS. The quenching experiment and electron spin resonance (ESR) spectra indicated the generation of SO4- and OH in the CuFe2O4/PMS system, and the quantity experiments revealed that the generation concentration of SO4- was ten times higher than that of OH. The generation mechanism of SO4- and ·OH were investigated by ATR-FTIR and X-ray photoelectron spectroscopy (XPS) spectra. The effects of catalyst dosage, PMS and iohexol concentration on the removal of iohexol were studied, and various water matrix factors including solution pH, natural organic matter (NOM) concentration and inorganic ions were also considered. Based on the twelve intermediate products of iohexol detected by UPLC-QTOF/MS, the degradation pathway was proposed. The high catalytic activity and reusability of CuFe2O4 indicated that CuFe2O4 activating PMS is an effective and sustainable way for the treatment of iohexol.

Mechanistic insights into rapid sulfite activation with cobalt sulfide towards iohexol abatement: Contribution of sulfur conversion

Recently, activation of sulfite for production of sulfate radical (SO4•−) has emerged for abatement of organic contaminants. Herein, with regard to the excellent activation efficacy of Co(II) and the enhanced electron donating capacity by sulfur species, cobalt sulfide (CoS) was proposed for efficient sulfite activation towards iohexol abatement via SO4•−–based advanced oxidation processes. CoS exhibited better activation performance than typical CoO and Co3O4 with a sharp decline of iohexol within 0.5 min, for which superior electron transfer efficiency of CoS was confirmed by Electrochemical impedance spectroscopy (EIS). The contribution of SO4•− and HO• to iohexol abatement was demonstrated by radical quenching experiment and Electron paramagnetic resonance (EPR). The influences of various parameters (solution pH, CoS and sulfite dosage, iohexol concentration), co-existing anions (HCO3−, HPO42−, Cl− and NO3−) and humic acid on iohexol abatement were investigated, as well as, the effect of different water matrixes on iohexol abatement was also evaluated. A possible mechanism was proposed based on ionic strength experiment, Transmission electron microscope-Energy dispersive spectrometer (TEM-EDS), X-ray photoelectron spectroscopy (XPS) and Raman. The superior activation performance of CoS could be attributed to the inner-sphere complexation between CoS and sulfite and enhanced > Co(III)/>Co(II) recycling induced by reductive sulfur species via rapid electron transfer. In addition, the iohexol degradation pathways were analyzed. This study highlights the contribution of sulfur conversion in the sulfite activation process and is expected to provide a facile CoS enhanced sulfite activation method for efficient abatement of organic contaminants.

Persulfate enhanced visible light photocatalytic degradation of iohexol by surface-loaded perylene diimide/acidified biochar

Persulfate (PS) is extensively employed as an oxidant to develop the sulfate radical-based advanced oxidation processes for removing organic pollutants and various PS activation methods have been explored. Iohexol (IOH), as a typical iodinated X-ray contrast media, poses a threat to human health and ecological environment, which is difficult to be removed by conventional treatment methods. In our work, a photocatalytic coupling persulfate system was constructed for efficient IOH degradation. A novel binary photocatalyst of biochar loaded with perylene diimide (PDI/BC, PB) was successfully prepared via a one-pot water bath heating method, which achieved BC acidification and PDI self-assembly simultaneously. Different mass ratios of BC and PDI lead to variance in average particle size, electronegativity, bandgap width and electron/hole separation efficiency. The optimized efficiency of 10 mg/L IOH on PB-9 (PDI:BC = 1:9, w/w) reached 100% in 2 h with 1.5 mM sodium persulfate under visible light irradiation. Based on the results of trapping experiments and electron paramagnetic resonance, holes and hydroxyl radicals were the dominant active species and the free radical chain reaction and mutual conversion reaction of active species occurred. The amide hydrolysis, amine and C-OH oxidation, hydrogen extraction, deiodination and OH addition were observed during the degradation process. Density functional theory calculation was conducted to confirm the free radical attack sites. The findings of this work demonstrate that metal-free supramolecular loaded photocatalyst has the potential for application in the removal of organic pollutants for water remediation.

Accelerated photocatalytic degradation of iohexol over Co3O4/g-C3N4/Bi2O2CO3 of p-n/n-n dual heterojunction under simulated sunlight by persulfate

A novel Co3O4/g-C3N4/Bi2O2CO3 (BCCN) photocatalyst with p-n/n-n heterojunction was synthesized through a solvent-thermal method. The degradation efficiency of 20 mg/L iohexol reached 94 % in 60 min (kapp =0.0417 min−1) in BCCN/light/PS system, which was 2.8 and 6.5 times higher than systems of BCCN/light (kapp =0.0150 min−1) and BCCN/PS (kapp =0.0064 min−1). The g-C3N4 addition lowered conduction band of the prepared material to produce superoxide radicals, activate persulfate and further prevent the recombination of photoelectrons and holes. Superoxide radicals and singlet oxygens were dominant radicals for iohexol degradation. Besides, persulfate could act as electron acceptor to enhance efficiency of electron transfer. The interaction between sulfate, superoxide and hydroxyl radicals improved singlet oxygens production. Furthermore, theoretical calculation and liquid chromatography mass spectrometry were performed to analyze degradation pathway of iohexol in the system. Ultimately, the BCCN/light/PS system can provide a new method to degrade organic pollutants in aquatic environments.

Catalytic ozonation of iohexol with α-Fe0.9Mn0.1OOH in water: Efficiency, degradation mechanism and toxicity evaluation

Iohexol, a widely used iodinated X-ray contrast media, is difficult to completely degrade with the traditional water treatment process. Catalytic ozonation with synthesized α-Fe0.9Mn0.1OOH as the catalyst can significantly promote the degradation of iohexol relative to that with ozonation alone. Hydroxyl radicals play a predominant role during the degradation of iohexol. The effect of various factors, including catalyst dose, ozone dose, iohexol concentration and water matrix factors, on the catalytic performance were investigated. The presence of α-Fe0.9Mn0.1OOH in the catalytic system can significantly promote the removal of iohexol and mineralization of the dissolved organic carbon in real water samples. The intermediate products were determined by high-resolution liquid chromatography, and the reaction site was predicted by frontier electron density (FED) calculations. The degradation mechanism of iohexol followed the processes of H-abstraction, amide hydrolysis, amide oxidation, and ·OH substitution. Higher exposure concentrations of iohexol had a negative effect on the survival and hatching rates in the development of zebrafish embryos. The autonomic movement process and heartbeat rate of the zebrafish larvae showed significant differences as the exposure concentration of iohexol increased. The catalytic ozonation process with α-Fe0.9Mn0.1OOH can decrease the toxicity of iohexol containing water.

Highly efficient degradation of iohexol on a heterostructured graphene-analogue boron nitride coupled Bi2MoO6 photocatalyst under simulated sunlight

Iohexol (IOH), as a typical iodinated X-ray contrast media (ICMs) with potential threat to human health, is difficult to be removed with the conventional wastewater treatment methods. In this work, new boron nitride coupled Bi2MoO6 layered microspheres (BN/Bi2MoO6) composites were applied to remove IOH from water via photocatalytic degradation. The degradation constant kapp of IOH over 3.5 wt% BN/Bi2MoO6 was 0.016 min−1, which was 3.2 times that of Bi2MoO6 (0.005 min−1). The degradation rate of IOH on 3.5 wt% BN/Bi2MoO6 reached 92% in 150 min. The enhanced photocatalytic activity of BN/Bi2MoO6 can be attributed to the heterojunction between BN and Bi2MoO6. The matched type-I band alignment heterojunction of two semiconductors prominently improved the charge separation. Based on the trapping experiments, holes and superoxide radicals were proved to be the main active species for photocatalytic IOH degradation. Besides, the degradation products of IOH were analyzed by LC–HRMS and the possible degradation mechanism of IOH was also proposed in this work.

Kinetics and formation of disinfection byproducts during iohexol chlor(am)ination

In this study, the degradation kinetics, and the formation of disinfection byproducts (DBPs) during iohexol chlor(am)ination were studied. The chlorination kinetics can be described using a second-order model. As the pH of the solution increased, the apparent second-order rate constant of iohexol chlorination increased considerably. The reaction rate constants of iohexol with HOCl and OCl− were calculated as (3.75±0.70)×10-4 and (1.39±1.19)×10-4 M−1 s−1, respectively. In addition, the chloramination of iohexol followed tertiary kinetics, and the maximum apparent rate constant of 3.78×10-6 M−1 s−1 occurred at pH 7. NH4+ can promote the degradation of iohexol during chlorination, whereas Br− inhibits iohexol degradation during chloramination. The formation of conventional carbonated DBPs and emerging nitrogenated DBPs during chlor(am)ination of iohexol was measured. However, in the presence of bromide, the conversion of iohexol to toxic iodinated DBPs increased significantly during chlorination, and chlorination resulted in higher formation of toxic I-DBP compared to chloramination. Therefore, chloramine disinfection is preferred for treating raw water containing high bromide concentrations in terms of DBP formation control.

Kinetics of iohexol degradation by ozonation and formation of DBPs during post-chlorination

Degradation kinetics of the widely used iodinated X-ray contrast medium, iohexol, was investigated in this study by ozone advanced oxidation process (AOP). Factors influencing iohexol degradation, pH, ozone dosage, and the presence of different background ions were also evaluated. Results show that iohexol degradation during ozonation followed the pseudo-first-order kinetics well; the degradation rate increased with the increase of pH values and reached a maximum of 1.29(±0.05)×10−1 min−1 at pH 9. As the ozone concentration gradually increased from 0.342 to 1.13 mg/L, the corresponding pseudo-first-order rate constant of iohexol degradation increased from 7.25 (±0.30)×10−3 to 5.77(±0.26)×10−2 min−1. At pH 7, the presence of background ions have different inhibitory effects on iohexol during ozonation degradation. Br­ exhibited the strongest inhibitory effect followed by HCO3− and CO32-, while Cl­ possessed negligible influence. Less disinfection by-products (DBPs) were formed at circumneutral pH values and low bromine concentrations (< 10 μM), which can be beneficial for the operation of drinking water treatment plants to supply safe drinking water to the public.

Efficient activation of sulfite autoxidation process with copper oxides for iohexol degradation under mild conditions

Sulfite has been recently emerging as an appealing sulfate radical (SO4•−) precursor for efficient treatment of organic contaminants. Due to the negligible autoxidation of sulfite, activators are often introduced to accelerate sulfite autoxidation and the concomitant generation of SO4•−. Present heterogeneous activators are mostly not very effective under mild conditions (pH 7.0–8.0). In this work, efficient activation of sulfite with copper oxides including Cu2O and CuO for iohexol degradation under mild pH conditions is proposed. In a comparison of iohexol degradation efficiency by sulfite autoxidation activated with different metal oxides (Co3O4, CoO, α-Fe2O3, γ-Fe2O3, CuO and Cu2O), CuO and Cu2O with lower toxicity are efficient activators and removal efficiencies of ~95% can be obtained at pH 8.0. SO4•− is identified to be the major species contributing to the removal of iohexol by electron paramagnetic resonance (EPR) spectroscopy and quenching experiment. Based on the effect of ionic strength and copper leaching, sulfite is proposed to interact with copper oxides via inner-sphere coordination. Effect of critical influencing parameters and efficacy of copper oxides in real water matrixes are investigated. The results suggest that using copper oxides as activators is a new alternative to promote sulfite autoxidation process for rapid contaminants degradation.

Investigation of iohexol degradation kinetics by using heat-activated persulfate

In this study, we investigated the degradation kinetics of a commonly used iodinated contrast medium, iohexol, by using heat-activated persulfate. The results indicate that the iohexol concentration can be effectively reduced with a removal percentage higher than 85% despite the long reaction time (2–3 h). The iohexol disappearance fitted well with the pseudo-first-order kinetic model. The persulfate consumption almost reached the maximum value during the initial 5 min of the reaction. Subsequently, persulfate was no longer consumed, which resulted in a decrease in the reaction rate. The pseudo-first-order rate constant of iohexol degradation significantly increased with temperature but decreased with an increase in pH from 5 to 9. The results of the quenching experiments performed using ethanol and tert-butanol indicate that the role of hydroxyl radicals was more important than that of sulfate radicals in iohexol degradation during heat-activated persulfate oxidation. However, without heat activation, persulfate did not react with iohexol. Therefore, the effect of pH on the HO· concentration dominated the effect of pH on iohexol degradation. High concentrations of bicarbonate (≥5 mM), chloride (≥1 mM), and dissolved natural organic matter (≥5 mg/L) inhibited the degradation of iohexol due to the consumption of sulfate and hydroxyl radicals. The mineralization percentage was only 3.8% (no considerable improvement) when the temperature was increased to 80 °C. The molecular structures of the intermediates contained iodine with molecular weights higher than 377 Da. Moreover, the generation of iodide was detected. The experimental results suggest that special attention should be paid to the risk of the formation of disinfection by-products in the subsequent chlorine disinfection process when treating natural water containing iohexol through heat-activated persulfate oxidation.

Degradation of iohexol by Co2+ activated peroxymonosulfate oxidation: Kinetics, reaction pathways, and formation of iodinated byproducts

Iodinated X-ray contrast media (ICM) are a group of tri-iodinated aromatic compounds used in medical imaging of soft tissues. They are regarded as emerging contaminants, and widely detected in the effluents of wastewater treatment plants, surface water, and groundwater. In the present study, degradation of iohexol, a typical ICM agent, was systematically investigated in a Co2+ activated peroxymonosulfate (Co2+/PMS) oxidation process at neutral conditions. Experimental data revealed that the apparent rate of iohexol degradation was first-order with respect to the concentrations of both Co2+ and PMS. SO4− was found to induce the oxidative degradation of iohexol primarily. Presence of humic acid (HA) significantly inhibited the iohexol degradation, while the influence of Cl− was negligible. A total of 11 intermediates were identified by HPLC-MS/MS and three transformation pathways, i.e., cleavage of side chain, H-abstraction from side chain, and oxidative deiodination, were proposed. The degradation started with the oxidation of the side chains in iohexol molecule and followed by deiodination on the aromatic ring. Following the degradation of iohexol, formation of free iodine and iodinated disinfection byproducts (I-DBPs) was found. When 50 µM was treated with 1 mM PMS and 1 µM Co2+, the yields of iodoform and triiodoacetic acid reached 38.12 and 577.99 µg/L, respectively, in 12 h. In addition, the formation of I-DBPs was prominently enhanced by the presence of HA. Because I-DBPs are highly toxic, this study suggests the potential risks when SO4− is applied to degrade ICM compounds.

Kinetics and model development of iohexol degradation during UV/H2O2 and UV/[formula omitted] oxidation

The degradation rates and kinetics of one commonly used iodinated contrast medium, iohexol, were investigated and compared during ultraviolet (UV) photolysis, UV/H2O2 and UV/S2O82− advanced oxidation processes (AOPs). Results indicate that the iohexol degradation rate increased in the order of UV/H2O2 < UV irradiation < UV/S2O82− and followed pseudo-first-order kinetics. Increasing persulfate concentration significantly increased iohexol degradation rate, whereas increasing H2O2 concentration caused reverse effect. Radical scavenging test results show that UV photolysis, OH and ▪ radicals all contributed to iohexol degradation during UV/S2O82−, but OH was the main contributor during UV/H2O2 and was consumed by excess H2O2. The kinetic models of iohexol degradation by both AOPs were developed, and the reaction rate constants with OH and ▪ were calculated as 5.73 (±0.02) × 108 and 3.91 (±0.01) × 1010 M−1 s−1, respectively. Iohexol degradation rate remained stable at pH 5–9 during UV irradiation and UV/H2O2, but gradually decreased at pH 5–7 and remained stable at pH 7–9 during UV/S2O82−. The presence of anions displayed inhibitory effects on iohexol degradation during UV/S2O82− in the order of Cl− >HCO3− ≫ SO42−. UV/S2O82− AOP exhibited high degradation efficiency and stability on the basis of UV irradiation, which can be applied as a promising degradation method for iohexol. UV/S2O82− AOP can effectively mineralize iohexol to CO2 but promoted the generation of toxic iodoform (CHI3), and the subsequent chlorination had the potential to reduce the content of disinfection by-products; therefore, further evaluation of possible environmental hazards is warranted.

Oxidative degradation of iodinated X-ray contrast media (iomeprol and iohexol) with sulfate radical: An experimental and theoretical study

It has already been known that oxidative degradation of organochlorine (e.g. chlorophenols) is accompanied by de novo formation of new polychlorinated compounds, however, whether the similar scenario can happen during decomposition of iodine-containing pollutants is completely unknown. Here degradation of two iodinated X-ray contrast media (ICM), iomeprol and iohexol, by sulfate radical generated through Co(II)-mediated activation of peroxymonosulfate (PMS) was investigated. The influencing parameters, such as the initial concentrations of PMS and Co(II), the initial solution pH and natural water constituents were examined. The pseudo-first-order rate constant of iomeprol in the PMS/Co(II) system is more than twice of iohexol, with values of 7.7 × 10−2 and 3.5 × 10−2 min−1, respectively, indicating that iomeprol seems more susceptible to radicals attack than iohexol. The bimolecular rate constants for reaction of sulfate radical (SO4•−) with ICM were determined to be 1.8 × 1010 M−1 s−1 and 7.9 × 109 M−1 s−1 for iomeprol and iohexol, respectively. The low degrees of mineralization and identification of iodinated intermediates of iomeprol and iohexol indicate that the degradation of iomeprol and iohexol in the Co/PMS system were incomplete. A de novo formation of new polyiodinated compounds would not happen because most of released inorganic iodine were ultimately oxidized to iodate (IO3−), rather than the reactive iodinated agents. Based on the identified byproducts and quantum chemical calculation, eight main transformation pathways are proposed for the degradation of iomeprol and iohexol as follows: (a) deiodination; (b) hydrogen abstraction; (c) amide hydrolysis; (d) amino oxidation; (e) hydroxyl substituent; (f) transformed alkyl aromatic amides to aromatic carbamoyl; (g) dehydration; (h) oxidized primary alcohol groups to carboxyl groups.

Modelling of iohexol degradation in a Fe(II)-activated persulfate system

Iohexol can hardly be removed in conventional wastewater treatment processes due to its non-biodegradable and hydrophilic characteristics. In this study, a kinetic model was established to describe iohexol degradation in Fe (II)-activated persulfate system. The developed model can well predict iohexol degradation and evolution of sulfate radical with various initial iohexol and oxidant (ferrous iron and persulfate) concentrations under various water matrix. The rate constant of iohexol reacting with sulfate radical was calculated as (1.83 ± 0.10) × 109 M−1s−1. The effects of the two most common components in natural water bodies, chloride ion and natural organic matter (NOM) on iohexol degradation, were also studied. Both experimental data and model results showed that the low concentration of chloride ion promoted iohexol degradation while high concentration inhibited it, and NOM slightly inhibited iohexol degradation. Besides, radical quenching tests were employed to identify the main radicals formed in the system and further verified the model accuracy. The model is also capable of predicting the atrazine degradation with the correlation coefficients between the experimental data and predicted results above 0.97, suggesting the applicability of the established model for some other recalcitrant contaminant degradation in the Fe2+/PS system.

Comparison of inert and non-inert cathode in cathode/Fe3+/Peroxymonosulfate processes on iohexol degradation

To investigate the effect of cathode materials on organics degradation in a cathode/Fe3+/PMS process, different cathode materials (platinum, copper and iron) were selected and their performances were compared with iohexol as target organics. The optimal conditions were found to be different for different cathode/Fe3+/PMS processes. With a relatively high cathodic current input (2.0 mA/cm2), similar results were found for all the three cathode/Fe3+/PMS processes. With a small cathodic current input (not higher than 1.0 mA/cm2), the iohexol removal followed the order of Fe-cathode/Fe3+/PMS > Cu-cathode/Fe3+/PMS > Pt-cathode/Fe3+/PMS, due to the corrosion of Cu-cathode and Fe-cathode and the more serious corrosion of Fe-cathode than Cu-cathode. The corrosion of non-inert cathode materials (Cu-cathode and Fe-cathode) meant that these cathodes not only transmitted electrons but also participated in aqueous reactions, which complicated the mechanisms of cathode/Fe3+/PMS processes. The radical identification experiments indicated that SO4- was more important than OH for iohexol degradation in Cu-cathode/Fe3+/PMS process, while OH played a major role in Pt-cathode/Fe3+/PMS and Fe-cathode/Fe3+/PMS processes. The different reaction mechanisms resulted in different iohexol transformation pathways in cathode/Fe3+/PMS processes with different cathode materials.

Performance of Cu-cathode/Fe3+/peroxymonosulfate process on iohexol degradation.

Copper was used as a non-inert cathode material in a Cathode/Fe3+/peroxymonosulfate(PMS) system, and the performance of this novel Cu-cathode/Fe3+/PMS system was tested with a typical iodinated X-ray contrast media (iohexol) as target organics. The reaction mechanisms and the iohexol degradation pathways were investigated. The operational conditions of Cu-cathode/Fe3+/PMS process on iohexol degradation were optimized to be 1.0 mM Fe3+ dosage, 3.0 mM PMS dosage and 0.50 mA/cm2 of current input. The much lower current applied in the present study than previous reports would help to save energy and be more economical. Compared with typical inert cathode (Pt-cathode), the Cu-cathode/Fe3+/PMS process has better performance on both iohexol removal and deiodination, due to that Cu-cathode participated in Fe2+ regeneration and PMS activation via surface Cu°-Cu+(s)-Cu2+-Cu° redox cycle. Fe2+ could be produced via reactions between Fe3+ and Cu/Cu+(s) as well as cathodic reduction of Fe3+. SO4- was generated from PMS activation by Fe2+, Cu/Cu+(s) and cathodic reduction. OH was also generated in this process but SO4- played a dominant role in iohexol degradation. The intermediate products of iohexol and its transformation pathways were complex due to the varied reaction mechanisms involving both oxidation and reduction in Cu-cathode/Fe3+/PMS process.

Iohexol Degradation by Biogenic Palladium Nanoparticles Hosted in Anaerobic Granular Sludge.

To improve the degradation ability of anaerobic granular sludge (AGS) toward the iodinated contrast media (ICM) iohexol, biogenic nanoscale palladium (Pd) was formed in AGS via microbial reduction. The Pd hosted in AGS (Pd-AGS) was used for iohexol degradation. The effects of the electron donor, reaction medium, iodide ion fouling, and polymer embedding of the Pd-AGS on the reactivity were investigated. Our results showed the Pd-AGS increased the degradation rate of iohexol, with a conversion rate constant increased by 86.3-fold compared to the AGS control. Various organic compounds were investigated as electron donors to initiate the catalytic activity of Pd-AGS and the promotion achieved with the tested electron donors was in the following order: formate > lactate > ethanol > glucose > acetate. The Pd-AGS had high reactivity in deionized water at mild pH, and almost no reactivity under acidic (pH = 1.2) and alkaline (pH > 11) conditions. The presence of iodide ions in the medium inhibited the catalytic activity of Pd-AGS toward iohexol because of catalyst fouling. Embedding the Pd-AGS in alginate, chitosan, or polyvinyl alcohol (PVA) could prevent Pd loss but it also retarded the iohexol degradation rate. The Pd-AGS, as a combination of Pd catalyst and AGS, provides a novel strategy for iohexol degradation in polluted water and wastewater.

Degradation of iohexol by UV irradiation: kinetics, pathways and iodinated trihalomethanes formation during post-chlorination

Degradation of iohexol by UV irradiation: kinetics, pathways and iodinated trihalomethanes formation during post-chlorination

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

In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/H2O2, UV/H2O2/Fe2+). 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/H2O2 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/H2O2 process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix.