InterPore2023

Mechanistic studies on the adsorption of Iodinated Contrast Media agents on Activated Carbon

23 May 2023, 10:30

1h 30m

Poster Presentation (MS22) Manufactured Porous Materials for Industrial Applications Poster

Speaker

Ashfeen Ubaid Khan (Polytechnic University of Milan)

Description

We focus on the evaluation of the adsorption energy (EAd) of 24 Iodinated contrast media agents (ICMs) on activated carbon through Density Functional Theory (DFT) in silico simulations. The study is motivated by the emergence of concerns related to the impact of pharmaceuticals on the environment and human health [1,2]. Iodinated contrast media agents are typically used in radiology, primarily in CT scans for soft tissue imaging [3]. Their presence in the environment can be the source of hazard [4]. With an annual global consumption of 3.5 × 106 kg [5], ICMs have been frequently detected in surface water bodies as well as in groundwater systems with levels up to 100 µg/L [3]. While conventional water treatment technologies are unable to contain the release of ICMs into the environment, some studies document the possibility that toxic by-products resulting from the transformations of ICMs can affect water and soil systems [3,6]. Thus, there is a growing need for robust technologies for the removal of ICMs from aquatic environments. Most of the available studies focus only on a few selected ICMs such as diatrizoic acid, iopamidol, or iohexol [3]. Considering that there are more than 30 ICMs available commercially [7], our study is the first one providing a comprehensive analysis of a variety of these compounds. Due to its tunable physiochemical properties, activated carbon is a porous material of remarkable interest in the context of groundwater remediation practice [8]. Because of the complexity and uncertainty associated with the structure of activated carbon, we use monolayer graphene as a proxy model [9,10]. We find that overall strong adsorption energies (EAd) can be documented through our DFT studies. These range from -114 Kcal/mol for Iophendylate to -13 Kcal/mol for Methiodal. To enhance our knowledge about the fundamental mechanisms underpinning the adsorption of ICMs on activated carbon, we rely on a Quantitative structure-activity relationship (QSAR) regression modeling approach. The latter yields quantitative correlation between (a) chemical structure information which is, in turn, represented in terms of molecular descriptors, and (b) adsorption [11]. Our results suggest that descriptors such as the topological charge index and the Van Der Waals surface area (of aromatic atoms) are positively corelated to adsorption energy. Otherwise, other descriptors, such as, e.g., the ‘average Randic-like index from Burden matrix weighted by ionization potential’, are characterized by a negative correlation to EAd. Our results are intended as a first step to assist the assessment of the role of intermolecular interactions governing adsorption of ICMs on activated carbon surfaces and to enhance our ability to further improve (and possibly design) a new generation of porous media to be effectively employed as sorbents in this context.

References

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2. Kümmerer, Klaus. "The presence of pharmaceuticals in the environment due to human use–present knowledge and future challenges." Journal of environmental management 90.8 (2009): 2354-2366.
3. Christiansen, Cathrine. "X-ray contrast media - an overview." Toxicology 209.2 (2005): 185-187.
4. Sengar, Ashish, and Arya Vijayanandan. "Comprehensive review on iodinated X-ray contrast media: Complete fate, occurrence, and formation of disinfection byproducts." Science of The Total Environment 769 (2021): 144846.
5. Pérez, Sandra, and Damià Barceló. "Fate and occurrence of X-ray contrast media in the environment." Analytical and bioanalytical chemistry 387.4 (2007): 1235-1246.
6. Hou, Meiru, et al. "Degradation of iodinated X-ray contrast media by advanced oxidation processes: A literature review with a focus on degradation pathways." Chinese Chemical Letters (2022): 1001-8417.
7. DrugBank Online: X-Ray Contrast Media, Iodinated, DBCAT002273 (December 2022).
8. Fan, Dimin, Edward J. Gilbert, and Tom Fox. "Current state of in situ subsurface remediation by activated carbon-based amendments." Journal of environmental management 204 (2017): 793-803.
9. Wu, Luoming, et al. "Effect of liquid-phase O3 oxidation of activated carbon on the adsorption of thiophene." Chemical Engineering Journal 242 (2014): 211-219.
10. Xing, Wei, et al. "Superior CO 2 uptake of N-doped activated carbon through hydrogen-bonding interaction." Energy & Environmental Science 5.6 (2012): 7323-7327.
11. Roy, Kunal, Supratik Kar, and Rudra Narayan Das. A primer on QSAR/QSPR modeling: fundamental concepts. Springer, 2015.