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Decontamination of emerging pollutant using porous Metal-Organic Frameworks (MOFs) and silica-MOFs composites

Periodic Reporting for period 1 - Cleanup-MOFs (Decontamination of emerging pollutant using porous Metal-Organic Frameworks (MOFs) and silica-MOFs composites)

Reporting period: 2016-09-01 to 2018-08-31

Pharmaceuticals and Personal Care Products as Pollutants (PPCPs) are regarded as an emerging class of contaminants and are often released directly into the environment after passing through wastewater treatment plants that are not equipped to remove them. In general, PPCPs refer to any product used by individuals for personal healthcare/cosmetic reasons or by agribusiness to enhance growth or health of livestock (i.e. anti-inflammatory and analgesics, antidepressants). These compounds are a source of concern because they are widely used and then, released in large quantities. Furthermore, given an aging population and medical coverage expansion, drug prescription is expected to sharply increase over the coming decades.

PPCPs can be endocrine disruptors that mimic, enhance or inhibit the action of hormones. The presence of low concentrations of PPCPs has been associated to chronic toxicity and the development of pathogen resistances.The consequences of exposure over multiple generations to multitude of these compounds are unknown, involving a potential severe risk for health and environment.

In human health risk assessment, ingestion of food and water is considered a major route of exposure to many contaminants. Moreover, the therapeutic misadventures, illicit drug ingestion or attempted suicide by using of harmful substances is a major worldwide public health problem that causes both a significant cost and severe health problems, even death. Unfortunately, for the vast majority of these poisoning, there are no specific pharmacological antidotes and currently available detoxification methods are weak and poorly prescribed (i.e. gastric lavage).

In this context, a new class of crystalline porous materials known as Metal Organic Frameworks (MOFs) has attracted an increasing attention from academic and industrial domains. Compared to classical adsorbent materials, MOFs present several advantages: i) a versatile composition, ii) large structural variability, iii) important porosity, and iv) the easy modulation of their physicochemical properties. These features make them excellent candidates for the selective and important adsorption of large variety of toxins.
The OBJECTIVE of the present project is to develop MOFs specially tailored for the removal and degradation of very harmful pollutant (PPCPs) from wastewater, as well as for human/animal detoxification.
In agreement with these objectives the MC fellow has been working on the following research lines:
- Rational selection of MOFs and study of their stability.
- Evaluation of MOFs capacity in PPCPs adsorption.
The fellow has been working in the the rational selection of absorbent materials focusing on a meticulous choice of ligands and cationic units as building blocks to be used in structuring MOFs. An ideal adsorbent for PPCPs might present: i) adequate chemical stability, ii) high adsorption capacity, iii) good selectivity, iv) slow desorption kinetics, v) environmentally and biologically friendly composition and, when possible, vi) renerability, associated with a controlled toxin desorption.
In this maters, the fellow has synthetized 11 adsorbent materials and fully characterized by different techniques: i) X ray powder diffraction to study and check their crystalline structure; ii) infrared spectroscopy and N2 sorption capacity to prove the suitable porosity of the selected materials; iii) thermal stability studies and elemental analysis to check their composition; iv) Dynamic Light Scattering and Scanning Electron Microscopy to check their particle size.
Although their robustness, the structural and chemical resistance of these solids has been monitored under different simulated media, including: gastro-instestinal, simulated intestinal fluid and simulated wastewater media. In all studied materials, the crystallinity has been used to check theirs structural stability. Chemical stability and textural properties of the solids has been assessed by a combination of different methods. Taking into account all these results, the most chemical robust matrixes has been chosen for each different simulated media.
Regarding taks 2, the fellow has evaluated MOFs capacity in PPCPs adsorption. To accomplish this objective the fellow has selected two different model PPCPs: aspirin and atenolol. These model PPCPs molecules have been selected because their are wildly consumed, their have been used as self-poisoning drugs, and they are present in water (rivers, streams, etc.).
The previously selected MOFs, which have shown chemical stability under the different studied medias has been employed during this stage. The aspirin adsorption capacity of the selected MOFs has been studied in different biological media (gastric and intestinal). The adsorption isotherms of aspirin under biological medias has been measured to determine the aspirin adsorption capacity of the MOFs under study. In parallel the chemical stability of the selected MOFs has been assessed. The quantification of the release of MOFs components to the media and the adsorbed aspirin has been performed by high pressure liquid chromatography. According to these results, the two most promising materials has been tested under in vivo conditions (rat model) in order to use these materials as adsorbent in oral detoxification treatments. Orally administered upon an aspirin overdose, these MOFs are able to reduce the salicylate gastrointestinal absorption and toxicity, avoiding histological damage) while exhibiting exceptional gastrointestinal stability, poor intestinal permeation, and safety. These results led to a publication in two high impact journal and there is still work to be published.
On the other hand, the atenolol adsorption capacity of the selected materials has been studied in tap water. In parallel the chemical stability of the selected MOFs has been addessed. The results obtained in the elimination of atenolol from water has been compared against an standard material used in NORITHENE®CABOT filters in order to assess the significance of the results. Our materials are best suited for the capture of atenolol in water, eliminating 99% of the contaminant in 1 h (against the 82% from the carbon). These work is been prepared for their publication.
This proposal aims to significantly influence on the EU healthcare system given the increasing drug prescription and the subsequent massive release of toxic PPCPs in the media.The goal of this project is to develop advanced functional materials by controlling designed properties to meet specific applications needs, a topic that is in highly accordance with the Priority Areas marked by the EU in Horizon2020. In particular, this project fits well with nanotechnologies and advanced materials, specifically with the objectives Nanotechnology and Advanced Materials for more effective Healthcare and Materials solutions for use in the creative industry sector. The proposed project is not only devoted to the preparation of the materials but also to contaminants adsorption and degradation. In this sense, this project also fits well with the EU objective Water Innovation: Boosting its value for Europe Treasuring our water. Moreover, the possibility to move towards larger-scale pilot lines is envisioned due to the great experience in industrial application of the host institution, being able to facilitate industrial take-up and commercialization. This will strengthen Europe’s competitiveness.
Crystal structures of relevant highly robust MOFs