Abstract
The goal of this work was to develop polymer-based heterocycle for water purification from toxic pesticides such as difenoconazole. The polymer chosen for this purpose was cellulose nanocrystalline (CNC); two cellulose based heterocycles were prepared by crosslinking with 2,6-pyridine dicarbonyl dichloride (Cell-X), and derivatizing with 2-furan carbonyl chloride (Cell-D). The synthesized cellulose-based heterocycles were characterized by SEM, proton NMR, TGA and FT-IR spectroscopy. To optimize adsorption conditions, the effect of various variable such as time, adsorbent dose, pH, temperature, and difenoconazole initial concentration were evaluated. Results showed that, the maximum difenoconazole removal percentage was about 94.7%, and 96.6% for Cell-X and Cell-D, respectively. Kinetic and thermodynamic studies on the adsorption process showed that the adsorption of difenoconazole by the two polymers is a pseudo-second order and follows the Langmuir isotherm model. The obtained values of ∆G ° and ∆H suggest that the adsorption process is spontaneous at room temperature. The results showed that Cell-X could be a promising adsorbent on a commercial scale for difenoconazole. The several adsorption sites present in Cell-X in addition to the semi crown ether structure explains the high efficiency it has for difenoconazole, and could be used for other toxic pesticides. Monte Carlo (MC) and Molecular Dynamic (MD) simulation were performed on a model of Cell-X and difenoconazole, and the results showed strong interaction.
Highlights
The global concern about pollution caused by persistent pesticides emerges from their ability to bio-accumulate and bio-magnify in the environment, as well as causing many adverse effects for mankind [1,2,3]
This study aims to purify water from difenoconazole persistent pesticide using cellulose nanocrystalline cross-linked with 2,6-pyridine dicarbonyl dichloride (Cell-X) and cellulose derivatized with the heterocyclic compound 2-furan carbonyl chloride (Cell-D)
Two cellulosic based heterocyclic nano-polymers were prepared by reacting nanocrystalline cellulose with the crosslinking agent 2,6-pyridine di-carbonyl dichloride (Cell-X) and 2-furan carbonyl chloride (Cell-D)
Summary
The global concern about pollution caused by persistent pesticides emerges from their ability to bio-accumulate and bio-magnify in the environment, as well as causing many adverse effects for mankind [1,2,3]. The techniques reported in the literature for adsorption of pesticides from water include UV photolysis, electrochemical degradation, adsorption, fenton oxidation, ultrasonication, membrane technology, photo catalyst, and others. Difenoconazole has a solubility in water of (15 mg/L) at room temperature It is a very persistent pesticide with half-life in soil of more than seven months. This synthetic fungicide is used to prevent fungal diseases in plants owing to its systemic and broad-spectrum antifungal activities, for instance, basidiomycetes, ascomycetes and deuteromycetes. It is an ergosterol biosynthesis inhibitor which is used during the entire growing season of crops [1,18]. Previous studies on the fungicidal activity of difenoconazole implied that the biological activities of difenoconazole had enantioselectivity with the (2R,4S)-difenoconazole, with a more pronounced fungicidal activity than other forms [18,19]
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