The removal of organophosphorus pesticides from water using a new amino-substituted calixarene-based magnetic sporopollenin

Abstract

This study describes the synthesis, characterization and application of a new amino-substituted p-tert-butylcalix[4]arene-based magnetic sporopollenin, Calix-EPPTMS-MS (4), for the removal of two toxic organophosphorus pesticides, namely chlorpyrifos and diazinon, from contaminated water. The synthesized Calix-EPPTMS-MS (4) was characterized using FT-IR spectroscopy, a UV-Vis spectrophotometer, an elemental analyzer, scanning electron microscopy and energy dispersive spectroscopy. The pesticide removal efficiency of Calix-EPPTMS-MS (4) was evaluated through a batch-wise method and gas chromatography using a micro-electron capture detector (GC-μECD). Experimental parameterssuch as adsorbent dosage, pesticide concentration, solution pH and contact time were optimized. Excellent removal efficiencies of 96% for chlorpyrifos and 88% for diazinon were achieved at pH 7 within 10 min of contact time. Kinetic studies showed that both pesticides followed the pseudo-second-order rate model with a coefficient of determination (R²) of 0.999. The Langmuir and Dubinin–Radushkevich isotherms with high values of R² revealed that chlorpyrifos and diazinon adsorption on the Calix-EPPTMS-MS (4) adsorbent follows the chemisorption mechanism. Pesticide contaminated wastewater samples were used to assess the field applicability of the Calix-EPPTMS-MS (4) adsorbent. The results obtained showed that the newly fabricated adsorbent material Calix-EPPTMS-MS (4) is an efficient adsorbent and exhibits great potential as an alternative adsorbent for pesticide removal.