Uso de adsorbentes comerciales y desarrollo de un nano-adsorbente para la eliminación del metabolito de clorotalonil R471811 en agua para consumo humano

Several drinking water sources in the northern area of Cartago have reported contamination with chlorothalonil metabolites since 2022, with concentrations up to 200 times higher than the value allowed by legislation. These substances are potential carcinogenic agents. The Costa Rican Water and Sewer Institute (AyA), as the governing body, has had to supply the affected communities with drinking water through tanker trucks; however, this option represents a high cost for the institution. Alternatively, treatment systems such as membrane filtration or activated carbon can be found on the market. In either case, specialized knowledge is required to select the best option and to carry out its subsequent design and implementation. However, AyA and the Water Systems Administrative Associations (ASADAS) lack sufficient experience in the design of filters to treat microcontaminants (e.g., pesticides). Currently, the proposing group of project CF 1460101 is evaluating the removal of chlorothalonil metabolites using activated carbon. However, theoretical considerations and experimental results indicate that this adsorbent may be ineffective for the removal of two hydrophilic, negatively charged metabolites belonging to the benzene-sulfonic family: R417888 (log Kow = 1.6) and R471811 (log Kow = 0.7). This proposal focuses on the latter, which is more soluble in water. Initially, adsorption capacity will be evaluated on commercial adsorbents designed for anionic substances. The selected adsorbents will be: iron oxide, titanium oxide, and two anion exchange resins. From these, the two most promising will be selected, characterized, and compared against coconut-based activated carbon through batch adsorption tests. Two additional objectives of the project will focus on developing a nano-adsorbent based on Layered Double Hydroxides (LDH), also with the capacity to adsorb anionic substances. The material will be prepared in granular form, characterized, and tested for adsorption capacity, adsorption mechanisms, and the effect of interfering substances. After, the adsorption capacity of the prepared material will be compared with that of the two best commercial adsorbents, and its effectiveness will be modeled at scale using AdDesignS™ software. Finally, the design of a treatment system using the best adsorbent studied is being considered, applied to a population of approximately 1,200 people and a flow rate of 5 L/s of contaminated water. This will allow for a detailed estimate of the material's applicability on a full-scale in the area, providing a possible medium-term technical solution to the problem.

Evaluar la aplicación de adsorbentes comerciales y de un nano-adsorbente desarrollado experimentalmente en la remoción del metabolito de clorotalonil R471811 en agua destinada al consumo humano.

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