Synergistic Effect of Sorption and Hydrolysis by NU-1000 Nanostructures for Removal and Detoxification of Chlorpyrifos

Abstract

Organophosphate-based pesticides have remarkably contributed to the agriculture industry, but their toxicity has a large negative impact on the environment as well as on the health of humans and other living organisms. Most of the methods developed to remedy the organophosphate pesticide toxicity are very time-consuming and are based on their adsorption onto different materials and/or their degradation to nontoxic species. In this study, detoxification of three structurally different organophosphate pesticides was investigated using an NU-1000 metal-organic framework. We showed that NU-1000 is an excellent agent for fast (average time ≤ 3 min) and effective removal of organophosphate pesticides with an aromatic heterocyclic moiety. In particular, superior detoxification of chlorpyrifos solution after NU-1000 treatment was achieved after only 1 min. The combination of experimental and computational methods revealed that the synergic effects of sorption and hydrolysis are responsible for the superior removal of CHP by NU-1000. The sorption process occurs on the Zr node (chemisorption) and pyrene linkers (physisorption) following pseudo-first-order kinetics during the first minute, and a pseudo-second-order model fits the entire time range. The multilayer adsorption of chlorpyrifos or its hydrolyzed product, 3,5,6-trichloro-2-pyridinol, takes place on a pyrene linker, whereas the aliphatic part of the molecule remains chemisorbed on the Zr node. Such unique synergy between induced sorption and hydrolysis of chlorpyrifos by NU-1000 results in its fast and effective removal with rapid detoxification in non-buffered solutions.