Removal of iopromide and degradation characteristics in electron beam irradiation process

Department of Environmental Engineering (YIEST), Yonsei University, Heungup, Wonju, Republic of Korea.
Journal of hazardous materials (Impact Factor: 4.53). 05/2012; 227-228:126-34. DOI: 10.1016/j.jhazmat.2012.05.022
Source: PubMed


The aim of this study is to evaluate the removal efficiency of iopromide using electron beam (E-beam) irradiation technology, and its degradation characteristics with hydroxyl radical (OH) and hydrated electron (e(aq)(-)). Studies are conducted with different initial concentrations of iopromide in pure water and in the presence of hydrogen peroxide, bicarbonate ion, or sulfite ion. E-beam absorbed dose of 19.6 kGy was required to achieve 90% degradation of 100 μM iopromide and the E-beam/H(2)O(2) system increased the removal efficiency by an amount of OH· generation. In the presence of OH scavengers (10 mM sulfite ion), the required dose for 90% removal of 100 μM iopromide was only 0.9 kGy. This greatly enhanced removal was achieved in the presence of OH· scavengers, which was rather unexpected and unlike the results obtained from most advanced oxidation process (AOP) experiments. The reasons for this enhancement can be explained by a kinetic study using the bimolecular rate constants of each reaction species. To explore the reaction scheme of iopromide with OH· or e(aq)(-) and the percent of mineralization for the two reaction paths, the total organic carbon (TOC), released iodide, and intermediates were analyzed.

  • Source
    • "The goal of this study was to demonstrate that enhanced biodegradability is a common outcome of molecular transformation during AOP. While the products of iopromide that form during UV photolysis and AOP have been extensively investigated (Jeong et al., 2010; P erez et al., 2009; Kwon et al., 2012), their biodegradability as compared to the parent compound have not been assessed. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Iopromide is an X-ray and MRI contrast agent that is virtually non-biodegradable and persistent through typical wastewater treatment processes. This study determined whether molecular transformation of iopromide in a UV/H2O2 advanced oxidation process (AOP) can result in biodegradable products. The experiments used iopromide labeled with carbon-14 on the aromatic ring to trace degradation of iopromide through UV/H2O2 advanced oxidation and subsequent biodegradation. The biotransformation assay tracked the formation of radiolabeled (14)CO2 which indicated full mineralization of the molecule. The results indicated that AOP formed biodegradable iopromide products. There was no (14)C released from the pre-AOP samples, but up to 20% of all radiolabeled carbon transformed into (14)CO2 over the course of 42 days of biodegradation after iopromide was exposed to advanced oxidation (compared to 10% transformation in inactivated post-AOP controls). In addition, the quantum yield of photolysis of iopromide was determined using low pressure (LP) and medium pressure (MP) mercury lamps as 0.069 ± 0.005 and 0.080 ± 0.007 respectively. The difference in the quantum yields for the two UV sources was not statistically significant at the 95% confidence interval (p = 0.08), which indicates the equivalency of using LP or MP UV sources for iopromide treatment. The reaction rate between iopromide and hydroxyl radicals was measured to be (2.5 ± 0.2) × 10(9) M(-1) s(-1). These results indicate that direct photolysis is a dominant degradation pathway in UV/H2O2 AOP treatment of iopromide. Other iodinated contrast media may also become biodegradable after exposure to UV or UV/H2O2.
    Full-text · Article · Oct 2015 · Chemosphere
  • Source
    • "Advanced oxidation processes (AOPs) such as UV/H 2 O 2 , O 3 /H 2 O 2 , and electron beam/H 2 O 2 have been studied for the removal of ICMs (Huber et al. 2005; Ning and Graham 2008; Jeong et al. 2010; Kwon et al. 2012). AOPs promote partial removal of the ICMs and lead to generation of intermediates that can be more hazardous than the parent compounds (Putschew and Jekel 2003; Ternes et al. 2003; Pérez and Barceló 2007; Seitz et al. 2008; Jeong et al. 2010; Duirk et al. 2011; Kwon et al. 2012). Thus, an efficient post-treatment strategy should be developed for the complete removal of ICMs and their intermediates after ozone treatment. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The potential of granular activated carbon (GAC) to remove iopromide and its intermediates from ozone-treated river water was evaluated. Mass spectrum analysis showed that ozone treatment lead to partial removal of iopromide (m/z 791.8) with generation of various intermediates. GAC demonstrated a lower iopromide adsorption (1.60 μg/g) in the presence of natural organic matter (NOM) compared to NOM-free water (12.54 μg/g), indicating the inhibitory effect of NOM on iopromide adsorption. Ozone treatment of the influent reduced the inhibitory effect of NOM by altering its composition and inducing polarity shift. GAC post-treatment resulted in improved removal of residual iopromide and its intermediates from the ozone-treated influent. Application of such combined treatment of ozonation followed by GAC adsorption can be an effective strategy for the removal of iopromide and its intermediates from contaminated water streams.
    Full-text · Article · Oct 2015 · Water Air and Soil Pollution
  • Source
    • "Huber et al. (2005) also concluded that ozonation itself was insufficient for complete elimination of ICM from wastewater. Ning et al. (2009) combined ozone with ultrasound irradiation treatment and reported almost complete decay of selected X-ray contrast media, while Kwon et al. (2012) evaluated an effective removal of iopromide from municipal wastewater using electron beam irradiation technology. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Iodinated contrast media (ICM), which are used for radiological visualization of human tissue and cardiovascular system, are poorly biodegradable; hence, new methods of their removal are sought. In this study, the effectiveness of selected X-ray ICM removal by means of UV and UV/TiO2 pretreatment processes from synthetic hospital wastewater was demonstrated. The following compounds were investigated: iodipamide, iohexol, and diatrizoate. The experiments were as follows: (i) estimated susceptibility of the ICM to decay by UV radiation in different aquatic matrices, (ii) determined an optimal retention time of hospital wastewater in the UV reactor, (iii) determined optimum TiO2 concentration to improve the effectiveness of the UV pretreatment, and (iv) investigated removal of ICM by combination of the photochemical and biological treatment methods. The quantum yields of selected ICM decay in deionized water (pH = 7.0) were established as 0.006, 0.004, and 0.029 for iohexol, diatrizoate, and iodipamide, respectively. Furthermore, the experiments revealed that diatrizoate and iohexol removal in the UV/TiO2 process is more efficient than in UV process alone. For diatrizoate, the removal efficiency equaled to 40 and 30 %, respectively, and for iohexol, the efficiency was 38 and 27 %, respectively. No significant increase in iodipamide removal in UV and UV/TiO2 processes was observed (29 and 28 %, respectively). However, highest removal efficiency was demonstrated in synthetic hospital wastewater with the combined photochemical and biological treatment method. The removal of diatrizoate and iohexol increased to at least 90 %, and for iodipamide, to at least 50 %.
    Full-text · Article · May 2015 · Water Air and Soil Pollution
Show more