Polymeric Nanocomposite-Based Herbicide of Carboxymethyl Cellulose Coated-Zinc/Aluminium Layered Double Hydroxide-Quinclorac: A Controlled Release Purpose for Agrochemicals

In this work, the use of carboxymethyl cellulose (CMC) is highlighted in enhancing the controlled release behaviour of zinc/aluminium layered double hydroxide-quinclorac (Zn/Al-LDH-QC). The Zn/Al-LDH-QC-CMC nanocomposite were characterised using powder x-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric and derivative thermogravimetric analysis and field emission scanning electron microscopy. The release study was carried out in an aqueous solution of Na3PO4, Na2SO4 and NaCl, so as to mimic the environmental condition where the QC is frequently used. The Zn/Al-LDH-QC-CMC nanocomposites showed better performance in releasing QC, with prolonged release time ranging from 163–6083 min, compared to 99–2639 min for the uncoated nanocomposites. The hygroscopic nature of the CMC play a critical role in enhancing the release behaviour of the Zn/Al-LDH-QC-CMC. The kinetic study shows that the Zn/Al-LDH-QC-CMC follows the pseudo-second order kinetic model; hence the release mechanism occurred via dissolution of the CMC matrix and the ion exchange process. These results, therefore, indicate the potential of Zn/Al-LDH-QC-CMC in dealing with the downside effect of the excessive usage of herbicide in paddy cultivation.