RELEASE BEHAVIOR OF DICHLORPROP FROM ZN/AL-LDH-DICHLORPROP NANOCOMPOSITE INTO CHLORIDE, CARBONATE AND PHOSPHATE SOLUTIONS

Abstract

A release study of dichlorprop phenoxyherbicides from the interlayer of a Zn/Al-layered double hydroxide-dichlorprop nanocomposite was performed with various concentrations of sodium chloride, sodium carbonate and sodium phosphate and a mixture of sodium chloride, sodium carbonate and sodium phosphate in aqueous solution. The release study of dichlorprop showed that release is dependent on the concentration of the aqueous solution. The accumulated release percentage of dichlorprop phenoxyherbicides into the solution was found to be higher in solutions containing carbonate, phosphate, and a mixture of carbonate or phosphate anions. Confirmation of the release process was confirmed by the PXRD pattern of the powder recovered from highly concentrated solutions of sodium chloride, sodium carbonate, and sodium phosphate with basal spacing of 7.8 Å, 7.6 Å and 7.4 Å, is due to chloride, carbonate, and phosphate intercalation, respectively. The kinetic study revealed that dichlorprop release into sodium carbonate and sodium phosphate solutions is governed by pseudo-second order kinetics, while release into sodium chloride solution is governed by parabolic diffusion. This study shows that a layered double hydroxide might be used as a host for the controlled release of the phenoxyherbicide dichlorprop.