Porous starch citrate biopolymer for controlled release of carbofuran in the management of root knot nematode Meloidogyne incognita

Abstract

The undesirable environmental impacts of inappropriate application of pesticides have brought about research into new matrices for controlled release of pesticides. Porous starch citrate biopolymer was designed for the release of carbofuran in this experiment and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermo-Gravimetric Analysis (TGA) for functional group, surface morphology and thermal stability properties respectively. The SEM revealed highly stabilized porous starch citrate biopolymers with porous structures and gradients suitable for controlled release studies. The transmittance bands at 3347, 1714 and 1073 cm−1 for OH, CO and COC stretching vibrations further confirms the successful synthesis of the biopolymer. TGA showed an increase in the thermal stability after citric acid modification with one-step decomposition from 290 ᵒC to 500 ᵒC. From Korsemeyer-Peppas model, the carbofuran-porous starch citrate (CBFN/PRS/STH/CTRT) followed a lower diffusion release model with gradual increment in all the quantity of carbofuran loaded. An accelerated rate of diffusion percentage was seen in direct application of carbofuran. Egg hatch and mortality of juveniles were recorded on daily basis for seven days. Direct application of carbofuran (CBFN/DRT) and carbofuran-porous starch citrate biopolymer gave the best results with significant (p < 0.05) reduction in egg hatch and higher percentage mortality. The rate of release of carbofuran from the starch citrate bio polymer matrix was significantly lower than the direct application, and in spite of the slow rate of release, higher juvenile mortality and reduction in egg hatch was achieved. Keywords: Carbofuran, Environmental pollution, Porous starch, Biopolymer, Starch citrate