Studies on the intercalation of calcium–aluminium layered double hydroxide-MCPA and its controlled release mechanism as a potential green herbicide

Abstract

The intercalation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicide into the interlayer matrix of calcium–aluminium layered double hydroxide (CaAl LDH) host has been successfully done via the co-precipitation method to form CaAl-MCPA nanocomposite, proposing an eco-friendly alternative with an adjusted delivery system for herbicide application. The intercalation process is supported by powder X-ray diffraction analysis with an expanded interlayer spacing from 8.6 to 19.6 Å for nanocomposite pH 13, which is due to the inclusion of larger size anion in the interlayer. Next, the absence of a nitrate peak at 1,326 cm−1 and the presence of a newly formed peak at 1,416 cm−1 in the Fourier transformed infrared spectroscopy analysis also confirmed the process of the intercalation. The significant decrease in nitrogen content to 0.50% indicates the intercalation of MCPA using the carbon, hydrogen, nitrogen, sulphur analyser. The release rate of the MCPA anion in the aqueous solutions is initially rapid, followed by the slow release in the order of phosphate > carbonate > chloride and followed the pseudo-second-order kinetic model. Hence, the conducted studies exhibit the successful intercalation of the MCPA herbicide anion and its controlled release mechanism as a potential hybrid green herbicide.

Keywords

• layered double hydroxide
• hydrocalumite
• intercalation
• phenoxyherbicide
• controlled release