The synthesis and characterization of layered hydroxide salt interleaved with 4-chlorophenoxyacetic acid and its control release study as herbicide

Abstract

Herbicides are well known in agriculture to kill unwanted plants such as weeds that invading the crops and affecting its quality. However, the application of herbicides at a large scale can be alarming to the environment especially to the human health. The synthesized nanohybrid can minimize the negative impacts to the environment caused by the higher concentration of common herbicides as the system controls the delivery rate of the agrochemicals. In this study, Layered Hydroxide Salt (LHS) was used whereby has successfully interleaved with the herbicide, namely 4-chlorophenoxyacetic acid (4CPA) to form zinc layered hydroxide-4CPA (Z4CPA) nanohybrid. Z4CPA was synthesized by ion exchange method followed by hydrothermal treatment at anions concentration of 0.1 M. Characterization using PXRD validated the claim due to in the Z4CPA diffractogram, zinc oxide fingerprint peaks disappear while the basal spacing of 21.6 Å that complement the previous study signifying an interleaved metal hydroxide existed has indeed appeared. FTIR spectrum further shows that 4CPA prominent bands exist in the Z4CPA spectrum with slight changes in wavenumber hinting the possibility of interleaved happened due to the formation of new bands. The result from BET proves that the product was mesoporous material with increased surface area as compared to the zinc oxide precursor. The FESEM-EDX shows the surface morphologies from irregular to flaky shapes for ZnO and Z4CPA nanoybrid. Control release study was performed using UV-Vis spectroscopy in 0.01 M media solution of NaCl, Na2CO3 and Na3PO4 respectively after positive results were obtained from PXRD, FTIR, FESEM-EDX and BET analysis. The saturated release of the anions is in the order of phosphate>carbonate>chloride with percentages of 90%, 75% and 50%, respectively. This study indicates the potential application of LHS as a host for herbicide, 4CPA, with controlled release capability apart of providing an alternative for a low-cost and green herbicide.