Electrosynthesis of metal-organic frameworks (MOFs) using 4,4′methylene dianiline polymer and metals (Al, Cu, and Fe) for imidacloprid pesticide adsorption in the aquatic environment

Abstract

ABSTRACT Extensive use of imidacloprid in pest control and its unfavourable removal efficiency has resulted contamination of aquatic environments. Herein, 4,4ʹ-methylenedianiline nano-polymer (MDANP) as organic linkers and Cu, Fe, and Al as metal sources were used to synthesise several metal-organic frameworks (MOFs) nanomaterials. Three MOFs (MDANP/Cu, MDANP/Fe, and MDANP/Al) were synthesised by the electrochemical polymerisation method and used as a nano-adsorbent to remove imidacloprid from the aqueous environment. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transient electron microscopy (TEM), and Field-scattering scanning electron microscopy (FE-SEM) techniques were used to analyse physicochemical characteristics of produced MDANP and MOFs. Kinetic data have been fitted with pseudo-second-order models; according to the obtained correlation coefficients (R2 = 0.9993). Adsorption isotherm models suggested that except imidacloprid adsorption on MDANP, which was best explained by the Freundlich model (R2 = 0.9018), pesticide adsorption from MOFs was well explained by the Langmuir model (R2 = 0.9473). The removal efficiency of imidacloprid onto MDANP and MOFs decreased from 65.28% to 40.25% and from 61.56% to 36.89%, respectively, as the initial concentration of imidacloprid increased from 25 to 400 mg/L. The results showed that the highest adsorption of imidacloprid happens within 120 min for 150 mg of adsorbent. Under optimum conditions, a maximum adsorption capacity of 97.4 mg/g occurred. Thus, MDANP and MOFs have medium potential for environmental implications and can be exploited as nano-adsorbents of imidacloprid pesticides in aquatic environments.