Iopromide Research Articles

Catalytic hydrodehalogenation of iodinated contrast agents in drinking water: A kinetic study

The occurrence of iodinated contrast media (ICM) in water bodies represents a significant threat for public health due to their strong biochemical stability and recalcitrance to conventional water treatment systems. In this work, the feasibility of catalytic hydrodehalogenation (HDH) for the degradation of a representative group of ICMs (iohexol (IHX), iopromide (IPR), iopamidol (IPM) and diatrizoic acid (DIA)) is investigated. Complete degradation and deiodination of the isolated ICMs (1.6·10−2 mmol L−1) was achieved in less than 30 min in the presence of 0.25 g L−1 of different precious metal catalysts (Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3) under ambient conditions, closing iodine balance by >95 %. Based on the identified reaction intermediates and final products, reaction mechanisms were accordingly proposed. A sequential reaction pathway was proposed for DIA removal, while reaction mechanisms encompassing both sequential and concerted reaction steps were proposed for the non-ionic ICMs (IHX, IPR, and IPM). Subsequent kinetic models, which successfully described experimental data, were developed from the elucidated reaction mechanisms, considering all species involved in the reaction. The versatility of the process was finally demonstrated in the treatment of real aqueous matrices (surface water and tap water) spiked with the ICMs mixture, except in the case of Pt/Al2O3 which suffered deactivation due to surface poisoning by halides. For this catalyst, kinetic constants ranged from 0.31 to 0.22 min−1 in deionized water, and from 0.04 to 0.08 min−1 in surface water as the reaction matrix. Among the tested catalysts, Pd/Al2O3 showed the highest activity and stability for the removal of ICMs.

Environmental risk assessment of selected pharmaceuticals in hospital wastewater in nothern Vietnam

Pharmaceuticals are progressively employed in both human and veterinary medicine and increasingly recognized as environmental contaminants. This study investigated the occurrence of selected pharmaceuticals in influent and effluent of wastewater treatment plants of 12 hospitals in Hanoi and 3 northern cities of Vietnam during dry and rainy seasons. In addition, environmental risk of pharmaceuticals in both hospital influents and effluents were evaluated based on risk quotients (RQs). Nine selected pharmaceutical compounds including sulfamethoxazole (SMX), naproxen (NPX), diclofenac (DCF), ibuprofen (IBU), acetaminophen (ACT), carbamazepine (CBM), iopromide (IOP), atenolol (ATN), and caffeine (CAF) were frequently detected in most influent and effluent wastewaters of 12 investigated hospitals. Detected compound levels exhibited a wide range, from as low as 1 ng/L for DCF to as high as 61,772 ng/L for ACT. Among these compounds, ACT, CAF, SMX, and IOP were consistently detected at substantial concentrations in both influents and effluents. This investigation also highlighted potential risks posed by SMX, ACT, and CAF residues present in influents and effluents of hospital wastewater treatment plants (WWTPs) to aquatic ecosystem. These finding are expected to provide scientific-based evidence for the development of hospital waste management and environmental management programs in Vietnam.

Periphyton in urban freshwater facilitates transformation of trace organic compounds: A case study on iodinated contrast media

Introduction: Due to urbanization and demographic change trace organic compounds (TrOCs), synthetic chemicals such as pharmaceuticals, personal care products or biocides are an increasing problem in waterbodies affected by treated sewage. This contamination is particularly relevant when surface water is used for drinking water production, either directly or by bank filtration. Removal and transformation of TrOCs are affected by a variety of processes, and we hypothesize that periphyton, the mixture of photo- and heterotrophic biota attached to submerged surfaces of aquatic ecosystems, can facilitate TrOC transformation. Here we experimentally tested the influence of periphyton on different substrates on the transformation of iodinated contrast media (ICM). These hydrophilic compounds are problematic due to their poor removal by conventional wastewater treatment and high persistence of the triiodinated benzoic acid within aquatic environments.Methods: We added 100 μg L-1 of three ICM, iopromide (IOP), iopamidol (IOM) and diatrizoate (DIA) to batch experiments containing periphyton on artificial substrates or on invasive quagga mussels and to a column experiment with periphyton, quagga mussels and sediment from a bank filtration site in a lake.Results: IOP concentrations were reduced by up to 93% after 30 days in batch experiments with periphyton on artificial substrates and completely in treatments with mussels and periphyton. In contrast, no concentration decrease was observed for IOM and DIA. IOP reduction was positively correlated with periphyton biomass ranging from 0.7 to 9.2 g dry weight m-2 and negatively correlated with oxygen saturation. 9 of 12 known aerobic IOP transformation products frequently occurring in treated wastewater were found.Discussion: We suggest that periphyton facilitated IOP transformation by providing substrate for bacterial growth and enhanced bacterial growth rates due to algal photosynthesis, a co-oxidation catalyzed by ammonia oxidizing bacteria and by a stimulatory influence of labile carbon produced by periphytic algae on the microbially mediated decomposition of IOP. Periphyton is facilitated by increased nutrient supply of dense mussel stands or by an increased surface area provided in dense macrophyte stands. Consequently, changes in the abundance of these littoral communities by invasion or management can affect TrOC transformation and thus water quality for drinking water production from urban freshwaters.

Degradation of iopromide during the UV-LED/chlorine reaction: Effect of wavelength, radical contribution, transformation products, and toxicity

Three different UV-LED wavelengths (265, 310, and 365 nm) were used in the UV-LED/chlorine reaction to investigate the degradation mechanism of iopromide (IPM) at different wavelengths, a representative iodinated contrast media compound. The degradation rate (k′IPM) increased from pH 6–8 at 265 nm, but, decreased as the pH increased up to 9 at 310 nm and 365 nm. Radical scavenging experiments showed that reactive chlorine species (RCS) are the dominant radical species at all wavelengths, but a higher contribution of OH• was observed at lower pH and longer wavelengths. The contribution of RCS decreased but the contribution of OH• increased as the wavelength increased. Among RCS, the largest contribution was found to be ClO•. Total nine transformation products (TPs) were identified by LC-QTOF-MS during the UV-LED/chlorine reaction at 265 nm. Based on the identified TPs and their time profiles, we proposed a degradation pathway of IPM during UV-LED/chlorine reaction. The Microtox test using V. fischeri showed that no significant increase in toxicity was observed at all wavelengths. The synergistic effect of UV-LED and chlorine was greater at a higher wavelength by the electrical efficiency per order (EEO) calculation.

Efficient Degradation of Iopromide by Using Sulfite Activated with Mackinawite.

Iopromide (IOP), an iodinated X-ray contrast medium (ICM), is identified as a precursor to iodide disinfection byproducts that have high genotoxicity and cytotoxicity to mammals. ICM remains persistent through typical wastewater treatment processes and even through some hydroxyl radical-based advanced oxidation processes. The development of new technologies to remove ICMs is needed. In this work, mackinawite (FeS)-activated sulfite autoxidation was employed for the degradation of IOP-containing water. The experiment was performed in a 500 mL self-made temperature-controlled reactor with online monitoring pH and dissolved oxygen in the laboratory. The effects of various parameters, such as initial pH values, sulfite dosages, FeS dosages, dissolved oxygen, and inorganic anions on the performance of the treatment process have been investigated. Eighty percent of IOP could be degraded in 15 min with 1 g L−1 FeS, 400 μmol L−1 sulfite at pH 8, and high efficiency on the removal of total organic carbon (TOC) was achieved, which is 71.8% via a reaction for 1 h. The generated hydroxyl and oxysulfur radicals, which contributed to the oxidation process, were identified through radical quenching experiments. The dissolved oxygen was essential for the degradation of IOP. The presence of Cl− could facilitate IOP degradation, while NO3− and CO32− could inhibit the degradation process. The reaction pathway involving H-abstraction and oxidative decarboxylation was proposed, based on product identification. The current system shows good applicability for the degradation of IOP and may help in developing a new approach for the treatment of ICM-containing water.

Evaluation and Prediction of Removal Efficiency of Pharmaceuticals in the Simulated O3 and UV/H2O2 Process for Drinking Water Treatment Process in the Downstream of Nakdong River

Objectives : In the case of pharmaceuticals with high possibility of inflow into the large drinking water treatment plant (DWTP) located in the downstream of the Nakdong River, we tried to evaluate the removal efficiency of pharmaceuticals in the both ozone (O3) and the UV/H2O2 treatment as an alternative of post-O3 process. It was intended to be used as data for the advanced WTP project by prediction of the removal efficiency in the O3 and UV/H2O2 processes with varying water quality conditions.Methods : O3 and UV/H2O2 process were performed for 19 kinds of pharmaceuticals in the sand-filtered water of DWTP. In order to evaluate the removal efficiency in deionized water (DI) and sand-filtered water (SFW) matrices, 19 pharmaceuticals were spiked at a concentration of 100 ng/L, respectively. In the O3 process, the specific O3 dose was 0.1∼2.0 gO3/gDOC (0.25∼5.0 mgO3/L). In the UV/H2O2 process, H2O2 (5 and 10 mg/L) was added to the sample before UV was irradiated (0∼1,500 mJ/cm2).Results and Discussion : In the case of simulated post-O3 process, the removal efficiency of high-ozone reactive pharmaceuticals (kO3 6.5×102∼2.6×106 M-1 s-1) was up to 92% at the specific O3 dose of 0.2 gO3/gDOC. However, the removal efficiency of iopromide (IPM) and primidone (PRM) was only 36∼45% in the same O3 dose (0.2 gO3/gDOC) due to the low O3 reactivity (kO3 < 1 M-1 s-1). A specific O3 dose of 2.0 gO3/gDOC (=5 mgO3/L) was required to achieve a removal efficiency of over 90% for IPM and PRM, indicating that these O3-refractory pharmaceuticals are difficult to control by O3 process. In the case of simulated UV/H2O2 (10 mg/L H2O2) process, the removal efficiency of 19 pharmaceuticals at the UV fluence of 500 and 1,000 mJ/cm2 were 63∼99% and 87∼99%, respectively, and caffeine (CFN) had the lowest removal efficiency. For the O3-refractory pharmaceuticals (i.e., IPM and PRM), the removal efficiency was higher in the UV/H2O2 process than that in the O3 process due to the high reactivity with OH radical (kOH = 3.3×109 and 5.2×109 M-1 s-1). Prediction of removal efficiency for pharmaceuticals in the O3 and UV/H2O2 process was performed using chemical kinetics model to evaluate the change in removal efficiency with varying DOM concentration. As a result of prediction model for O3, when the DOM concentration increased from 1.5 to 3.0 mg/L, the removal efficiency of IPM and PRM decreased by 22∼24% and 15∼24%, respectively. In the case of UV/H2O2 process (10 mg/L H2O2 and UV fluence of 500~1,000 mJ/cm2), the removal efficiency of 16 kinds of pharmaceuticals was reduced by 0∼29%, and the degree of reduction in the removal efficiency of CFN was the highest.Conclusions : As a result of evaluation and prediction of the removal efficiency of pharmaceuticals in the O3 and UV/H2O2 treatment processes, it is confirmed that the possibility of applying the UV/H2O2 treatment as an alternative process to the O3 to abatement of pharmaceuticals.

Acetylbritannilactone attenuates contrast-induced acute kidney injury through its anti-pyroptosis effects.

Contrast-induced acute kidney injury (CI-AKI) is a severe complication caused by intravascular applied radial contrast media (CM). Pyroptosis is a lytic type of cell death inherently associated with inflammation response and the secretion of pro-inflammatory cytokines following caspase-1 activation. The aim of the present study was to investigate the protective effects of acetylbritannilactone (ABL) on iopromide (IOP)-induced acute renal failure and reveal the underlying mechanism. In vivo and in vitro, IOP treatment caused renal damage and elevated the caspase-1 (+) propidium iodide (PI) (+) cell count, interleukin (IL)-1β and IL-18 levels, lactate dehydrogenase (LDH) release, and the relative expression of nucleotide-binding domain, leucine-rich repeat containing protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), and gasdermin D (GSDMD), suggesting that IOP induces AKI via the activation of pyroptosis. Furthermore, the pretreatment of ABL partly mitigated the CI-AKI, development of pyroptosis, and subsequent kidney inflammation. These data revealed that ABL partially prevents renal dysfunction and reduces pyroptosis in CI-AKI, which may provide a therapeutic target for the treatment of CM-induced AKI.

A low pressure SWCNT‐ENM sandwich membrane system for the removal of PPCPs from water

AbstractWhile carbon nanotubes are known as efficient adsorbents for removal of a number of contaminants from water, the possibility of their leaching into drinking water has prevented their application in water treatment. In this study, single walled carbon nanotubes (SWCNT) were sandwiched between two electrospun nanofibre membranes (ENM). The relatively small pore size of the ENM prevented the mechanically entangled nanotubes from passing through and contaminating the water. The performance of the SWCNT‐ENM was evaluated in a lab‐scale setup for the removal of PPCPs. For this purpose, a feed solution spiked with known concentrations of six PPCPs was passed through the membrane system. The target substances included acetaminophen (ACT), bezafibrate (BZF), iopromide (IOP), diclofenac (DCF), carbamazepine (CBZ), and sulphamethoxazole (SMX). The same test was also conducted using a single contaminant (ACT). Results demonstrated a decrease in the overall percent removal of PPCPs as feed flow rate and PPCP concentration increased. For multi‐component feeds containing equal amounts of the aforementioned PPCPs, the overall percent removal decreased from 90.8% to 71.0% when increasing the feed concentration from 30 to 600 μg/L. Experiments using sandwiched powdered activated carbon (PAC) showed that the dynamic adsorption capacity of PPCPs by SWCNT‐ENM was higher than that of PAC‐ENM, and remained unaffected by the feed composition. In addition, the high porosity of this novel membrane allowed for flow of water with low resistance such that the trans‐membrane pressure was found to be as low as 4 kPa at a pure water flux of 330 L/m2h.

Resolving the kinetic and intrinsic constraints of heat-activated peroxydisulfate oxidation of iopromide in aqueous solution

Iopromide (IOP) has been identified as one of the most persistent pharmaceuticals in wastewater treatment processes, however, kinetic and intrinsic factors constraining its fast removal in advanced oxidation processes (AOPs) are yet to be resolved. Here oxidation of IOP by heat-activated peroxydisulfate (PDS) was investigated both experimentally and theoretically. Rates of IOP degradation were enhanced by elevating solution temperature and acidity. An apparent kinetic rate equation was developed, based on the pseudo-first-order reaction model and assumption of steady state of SO4−. The common water constituents showed inhibitory effects on IOP decomposition to various extent. An insufficient supply of SO4− was considered as the major kinetic constraint. Eight byproducts were identified and most of which had intact triiodinated benzene ring. O-demethylation, oxidation of amino moiety and oxidation/elimination of alcohol groups are proposed as the primary degradation pathways, in accordance with the incomplete mineralization and non-detectable release of inorganic iodine. Quantum chemical calculations predict that oxidation of alkyl chains of IOP preferentially occurs and IOP byproducts with shorter side chains and intact triiodinated ring are more reactive than IOP. By virtue of the identified kinetic and intrinsic constraints, strategies to maximize degradation efficiency of IOP are proposed.

Improved reductive transformation of iopromide by magnetite containing reduced graphene oxide nanosacks as electron shuttles

The novel application of magnetite containing reduced graphene oxide nanosacks (MrGO-N) as electron shuttles to improve the reductive degradation of the pharmaceutical pollutant, iopromide (IOP), was evaluated. MrGO-N were synthesized by ultrasonicated nebulization process, and their physicochemical characterization was performed by potentiometric titrations, zeta potential, high resolution transmission electron microscopy (HR-TEM), X-ray diffraction, as well as by Raman and Fourier transform infrared spectroscopies. Results demonstrated the thermal reduction of precursor graphene oxide sheets, the removal of different oxygenated groups, and the successful assembly of magnetite nanoparticles (MNP) in the graphene sacks. Also, reduction experiments revealed 72% of IOP removal efficiency and up to 2.5-fold faster degradation of this pollutant performed with MrGO-N as redox catalysts in batch assays and with sulfide as electron donor. Chemical transformation pathway of IOP provides evidence of complete dehalogenation and further transformation of aromatic ring substituents. Greater redox-mediating ability of MrGO-N was observed, which was reflected in the catalytic activity of these nanomaterials during the reductive degradation of IOP. Transformation byproducts with simpler chemical structure were identified, which could lead to complete degradation by conventional methodologies in a complementary treatment process. Redox-mediating activity of MrGO-N could potentially be applied in wastewater treatment systems in order to facilitate the biodegradation of priority contaminants.

Detection of artificial sweeteners and iodinated X-ray contrast media in wastewater via LC-MS/MS and their potential use as anthropogenic tracers in flowing waters

The detection of wastewater impact on stream chemistry is often hindered by high background concentrations of ubiquitous solutes. In the present study we tested the applicability of artificial sweeteners (AS) and iodinated X-ray contrast media (ICM) as tracers to detect this impact by examining wastewater treatment plant (WWTP) effluents and surface water samples. The developed direct injection LC-MS/MS method enabled the detection of these anthropogenic micropollutants in aqueous samples down to trace level concentrations. The 2-h-composite sampling of WWTP effluent revealed fluctuating ICM concentrations between and within days with highest concentrations at the end of the week. Diatrizoic acid (DTZ) and iopromide (IOP) were the predominant ICM with concentrations up to 7 μg/L. Concentrations of the AS acesulfame (ACE) fluctuated between 0.5 μg/L and 1 μg/L. Concentrations of AS and ICM in surface water were both associated with wastewater impact. DTZ contamination was more widespread whereas some sampling points exhibited a more pronounced contamination with non-ionic ICM. Surface water was frequently contaminated with AS. Particularly ACE was detected in every surface water sample indicating that it is chemically stable and that inputs to the aquatic environment via WWTP effluents are widespread. The broad application of ACE as food additive enables its application as a tracer throughout Germany. Furthermore, the developed LC-MS/MS method enables rapid detection of ACE down to the low ng/L-range. Nonetheless, DTZ or IOP could be used in addition to ACE to verify anthropogenic influences on natural waters.

Electrochemical oxidation of key pharmaceuticals using a boron doped diamond electrode

Abstract This study assesses the degradation by electrochemical oxidation via boron doped diamond (BDD) electrodes of the selected pharmaceutical compounds iopromide (IOP), sulfamethoxazole (SMX), 17-alpha-ethinylestradiol (EE2) and diclofenac (DCF) in simulated wastewater and real hospital effluent wastewater. The influence of the flow rate in the electrochemical cell, applied current, initial compound concentration and wastewater matrix (simulated (SWW) versus real effluent (RWW) wastewater) was evaluated. A kinetic evaluation confirmed that the degradation can be described via pseudo first-order reaction kinetics for all experimental conditions tested. It was shown that SMX, EE2 and DCF degraded readily in SWW and RWW. The degradation of IOP was significantly slower, which is in agreement with previously reported slow degradation kinetics using typical advanced oxidation processes. Activation energies for the degradation reactions were calculated. The flow rate in the electrochemical cell had only a moderate effect on the degradation rate of EE2 and DCF. The applied current, however, had a major effect. The BDD electrochemical oxidation was shown to be an effective technique for removing pharmaceutical components from the effluent of a biological hospital wastewater treatment plant. However, the slower degradation of transformation products should be taken into account, when a full mineralization of the pharmaceuticals is pursued.

Stropharia rugosoannulata and Gymnopilus luteofolius: Promising fungal species for pharmaceutical biodegradation in contaminated water

Pharmaceuticals are environmental micropollutants that pose an emerging challenge because they are poorly eliminated in conventional wastewater treatment plants. Over the last decade, many attempts have been made to solve this problem, and wastewater fungal treatment is a promising alternative. In this study, six different ligninolytic fungi (Trametes versicolor, Ganoderma lucidum, Irpex lacteus, Stropharia rugosoannulata, Gymnopilus luteofolius and Agrocybe erebia) were studied as bioremediation candidates for the removal and degradation of six recalcitrant pharmaceutical micropollutants: Carbamazepine (CBZ), Venlafaxine (VFX), Iopromide (IPD), Diclofenac (DCF), Cyclophosphamide (CFD) and Ifosfamide (IFD). Self-immobilization in a pellet shape was achieved for all fungal mycelia (which was the first time that this was reported for S. rugosoannulata, G. luteofolius, and A. erebia). Biodegradation achievement was greater than 90% for IPD with G. luteofolius and greater than 70% for CBZ with S. rugosoannulata, which suggests a great potential for this alternative biological treatment. Besides, this was the first report where fungal treatment achieved CFD and IFD removals greater than 20% for the treatment with T. versicolor, G. lucidum and S. rugosoannulata.

Feasibility of Peripheral Artery CT Angiography under 70 kV with 50 ml Contrast Medium on the Third-generation Dual-source CT.

Objective To evaluate the feasibility of peripheral artery CT angiography (CTA)under 70 kV with 50 ml contrast medium on the third-generation dual-source CT. Methods Totally 82 patients who were equally randomized into two groups:70 kV group:the scan was performed under 70 kV tube voltage+50 ml iopromide on the third-generation dual-source CT;and 100 kV group:the scan was performed under 100 kV tube voltage+90 ml iopromide on the second-generation dual-source CT. The CT number of abdominal aorta,bilateral common iliac arteries,common femoral arteries,superficial femoral arteries,popliteal arteries and arteries of the calf were measured and contrast to noise ratio(CNR),signal to noise ratio(SNR)were calculated. The image quality was compared between these two groups. Results The dose-length product was (195.8±46.9)mGy·cm in 70 kV group,which was significantly lower than that in 100 kV group (461.6±57.9)mGy·cm,and was decreased by 57% (t=-22.848,P=0.000). Compared with the 100 kV group,the CT number of the proximal abdominal aorta in 70 kV group was significantly lower(t=-2.502,P=0.014),while the CT number of superficial femoral arteries (t=3.053,P=0.003)and popliteal arteries (t=4.013,P=0.000)was much higher in 70 kV group. SNR and CNR of proximal abdominal aorta,distal abdominal aorta,bilateral common iliac arteries,common femoral arteries,superficial femoral arteries,popliteal arteries and arteries of the calf were significantly lower in 70 kV group than those in 100 kV group (all P<0.05). The artifacts in abdominal aorta (t=2.893,P=0.000)and feet arteries (t=3.776,P=0.000)were higher in 70 kV group than those in 100 kV group,the enhancement of abdominal aorta (t=-1.000,P=0.002)and feet arteries (t=2.893,P=0.010)were lower in 70 kV group,the enhancement of femoral-popliteal arteries (t=-1.000,P=0.000)and arteries of calf (t=4.261,P=0.000)were higher in 70 kV group. Compared with the 100 kV group,the image noise in aorta (t=2.048,P=0.044),femoral-popliteal arteries (t=8.370,P=0.000),arteries of the calf (t=8.315,P=0.000)and feet arteries (t=7.202,P=0.000)were higher in 70 kV group. Conclusion Compared to conventional scan protocol,using 70 kV tube voltage with 50 ml contrast medium to perform peripheral artery CTA can assure the image quality and meanwhile remarkably reduce the radiation dose and the use of contrast medium.

Tailoring partially reduced graphene oxide as redox mediator for enhanced biotransformation of iopromide under methanogenic and sulfate-reducing conditions

This work reports the first successful application of graphene oxide (GO) and partially reduced GO (rGO) as redox mediator (RM) to increase the biotransformation of the recalcitrant iodinated contrast medium, iopromide (IOP). Results showed that GO-based materials promoted up to 5.5 and 2.8-fold faster biotransformation of IOP by anaerobic sludge under methanogenic and sulfate-reducing conditions, respectively. Correlation between the extent of reduction of GO and its redox-mediating capacity was demonstrated, which was reflected in faster removal and greater extent of biotransformation of IOP. Further analysis indicated that the biotransformation pathway of IOP involved multiple reactions including deiodination, decarboxylation, demethylation, dehydration and N-dealkylation. GO-based materials could be strategically tailored and integrated in biological treatment systems to effectively enhance the redox conversion of recalcitrant pollutants commonly found in wastewater treatment systems and industrial effluents.

Photodecomposition of iodinated contrast media and subsequent formation of toxic iodinated moieties during final disinfection with chlorinated oxidants

Large amount of iodinated contrast media (ICM) are found in natural waters (up to μg.L−1 levels) due to their worldwide use in medical imaging and their poor removal by conventional wastewater treatment. Synthetic water samples containing different ICM and natural organic matter (NOM) extracts were subjected to UV254 irradiation followed by the addition of chlorine (HOCl) or chloramine (NH2Cl) to simulate final disinfection. In this study, two new quantum yields were determined for diatrizoic acid (0.071 mol.Einstein−1) and iotalamic acid (0.038 mol.Einstein−1) while values for iopromide (IOP) (0.039 mol.Einstein−1), iopamidol (0.034 mol.Einstein−1) and iohexol (0.041 mol.Einstein−1) were consistent with published data. The photodegradation of IOP led to an increasing release of iodide with increasing UV doses. Iodide is oxidized to hypoiodous acid (HOI) either by HOCl or NH2Cl. In presence of NOM, the addition of oxidant increased the formation of iodinated disinfection by-products (I-DBPs). On one hand, when the concentration of HOCl was increased, the formation of I-DBPs decreased since HOI was converted to iodate. On the other hand, when NH2Cl was used the formation of I-DBPs was constant for all concentration since HOI reacted only with NOM to form I-DBPs. Increasing the NOM concentration has two effects, it decreased the photodegradation of IOP by screening effect but it increased the number of reactive sites available for reaction with HOI. For experiments carried out with HOCl, increasing the NOM concentration led to a lower formation of I-DBPs since less IOP are photodegraded and iodate are formed. For NH2Cl the lower photodegradation of IOP is compensated by the higher amount of NOM reactive sites, therefore, I-DBPs concentrations were constant for all NOM concentrations. 7 different NOM extracts were tested and almost no differences in IOP degradation and I-DBPs formation was observed. Similar behaviour was observed for the 5 ICM tested. Both oxidant poorly degraded the ICM and a higher formation of I-DBPs was observed for the chloramination experiments compared to the chlorination experiment. Results from toxicity testing showed that the photodegradation products of IOP are toxic and confirmed that the formation of I-DBPs leads to higher toxicity. Therefore, for the experiment with HOCl where iodate are formed the toxicity was lower than for the experiments with NH2Cl where a high formation of I-DBPs was observed.

Evaluation of the O3/graphene-based materials catalytic process: pH effect and iopromide removal

Graphene-based materials, including graphene oxide (GO), reduced-graphene oxide (rGO), and non-oxidative graphene (nOG) were evaluated for catalytic ozonation in water solutions. Among the graphene-based materials evaluated for catalytic ozonation, it was confirmed that rGO was unsuitable to apply to the ozone (O3)/graphene-based materials catalytic process because the high electron mobility of rGO prevented the transformation of O3 into hydroxyl radicals (OH). On the other hand, GO, which had sufficient oxygenated functional groups on the surface, decomposed and generated the most amount of O3 and OH, respectively. Although O3/nOG process produced a lower amount of OH than O3/GO process, nOG was more effective than GO for the transformation yields of O3 into OH. Furthermore, nOG could generate OH not only in the bulk phase, but also on the surface of nOG during catalytic ozonation. However, iopromide (IPM) was effectively removed during O3/GO process due to the more OH generated in the bulk phase than O3/nOG process.

Role of the intrinsic properties of partially reduced graphene oxides on the chemical transformation of iopromide

The role of the intrinsic properties of graphene oxide (GO) and partially reduced graphene oxide (rGO), and their use as redox mediator (RM) is reported, for the first time, on the chemical transformation of iopromide (IOP), an iodinated X-ray contrast medium, under anaerobic conditions. The structural and physicochemical properties of GO containing different types of oxygenated groups, were analyzed by Boehm titrations, point of zero charge (pHPZC), pKa's distribution, scanning electron microscopy (SEM), electrochemical analysis, as well as by Raman, Fourier transform infrared and UV–Vis spectroscopy. Complete characterization of GO-based materials revealed the removal of different oxygenated groups, such as epoxy and hydroxyl groups, and a transition from an amorphous to a more crystalline structure on partially reduced GO. Moreover, when rGO materials were tested as RM, they promoted a faster and greater extent of IOP transformation up to 5.2-fold with sulfide as electron donor. Results showed a correlation between the reduction degree of GO and its ability to act as RM, which was reflected in the dehalogenation and transformation degree of IOP. Additionally, the chemical transformation pathway of IOP is proposed based on HPLC-MS analysis.

Applied research of CT angiography of lower extremities by using 100 kVp and iodixanol(270 mg I/ml) combined with iDose(4) iterative reconstruction technique

To evaluate the feasibility of CT angiography of lower extremities by using 100 kVp as tube voltage and Iodixanol(270 mg I/ml) as contrast medium combined with iDose(4) iterative reconstruction technique. A total of 52 continuous patients with clinically suspected lesions of lower extremity arteries underwent CT angiography of lower extremities, divided into 2 groups, and different scan protocols were adopted. "double low" group included 26 patients using 100 kVp, Iodixanol (270 mg I/ml) and iDose(4) -4 iterative reconstruction algorithm; routine group included 26 patients using 120 kVp, Iopromide(370 mg I/ml) and filtered back projection reconstruction algorithm. The total amount of contrast medium in both groups was 95 ml. Artery CT value and background noise at the level of L4 vertebral, hip, knee and ankle were measured, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated, and the quality of images was evaluated subjectively. Scan length (L), volume CT dose index (CTDI(VOL)) and dose length product(DLP) were recorded, and the effective dose (ED) was calculated. The measurement results and subjective evaluation were analyzed statistically. CTA results were analyzed with the digital subtraction angiography (DSA) as the "gold standard". (1) No significant difference was existed in gender, age, height, weight and body mass index (BMI) of these two groups (P > 0.05). (2) No significant difference was existed in artery CT value, SNR and CNR at the level of L4 vertebral, hip, knee and ankle of the two groups (P > 0.05). Compared with routine group, background noise of "double low" group at the level of hip and knee increased by 16.6% and 13.8%, respectively (P < 0.05). (3) The image quality of the two groups met the requirement of diagnosis, no significant statistical difference was existed in subjective evaluation (P > 0.05). (4) The CTDI(VOL), DLP, ED of "double low" group were lower than that of routine group, with significant statistical difference (P < 0.05). The total amount of iodine in "double group" was lower than that of routine group (25.6 g vs 35.2 g). (5) A total of 7 cases from "double low" group underwent DSA examination, and 18 pathological changes (stenosis and occlusion) were found totally, in which 16 matched CTA; 6 cases from routine group underwent DSA examination, and 15 pathological changes (stenosis and occlusion) were found totally, in which 13 matched. CTA. No significant statistical difference was existed between the two groups in diagnostic efficacy (P = 0.626). Using 100 kVp and Iodixanol (270 mg I/ml) combined with iDose(4) -4 iterative reconstruction technique for CT angiography of lower extremities, the image quality could meet the requirement for clinical diagnosis, the radiation dose and the volume of contrast medium could be lowered.

Immobilization of biogenic Pd(0) in anaerobic granular sludge for the biotransformation of recalcitrant halogenated pollutants in UASB reactors.

The capacity of anaerobic granular sludge to reduce Pd(II), using ethanol as electron donor, in an upflow anaerobic sludge blanket (UASB) reactor was demonstrated. Results confirmed complete reduction of Pd(II) and immobilization as Pd(0) in the granular sludge. The Pd-enriched sludge was further evaluated regarding biotransformation of two recalcitrant halogenated pollutants: 3-chloro-nitrobenzene (3-CNB) and iopromide (IOP) in batch and continuous operation in UASB reactors. The superior removal capacity of the Pd-enriched biomass when compared with the control (not exposed to Pd) was demonstrated in both cases. Results revealed 80% of IOP removal efficiency after 100h of incubation in batch experiments performed with Pd-enriched biomass whereas only 28% of removal efficiency was achieved in incubations with biomass lacking Pd. The UASB reactor operated with the Pd-enriched biomass achieved 81 ± 9.5% removal efficiency of IOP and only 61 ± 8.3% occurred in the control reactor lacking Pd. Regarding 3-CNB, it was demonstrated that biogenic Pd(0) promoted both nitro-reduction and dehalogenation resulting in the complete conversion of 3-CNB to aniline while in the control experiment only nitro-reduction was documented. The complete biotransformation pathway of both contaminants was proposed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis evidencing a higher degree of nitro-reduction and dehalogenation of both contaminants in the experiments with Pd-enriched anaerobic sludge as compared with the control. A biotechnological process is proposed to recover Pd(II) from industrial streams and to immobilize it in anaerobic granular sludge. The Pd-enriched biomass is also proposed as a biocatalyst to achieve the biotransformation of recalcitrant compounds in UASB reactors.