Kaolinite–Arabic gum composite as efficient adsorption material for chemically active compounds with potential insecticidal properties from Momordica charantia leave extract

Abstract

Synthetic insecticides used worldwide are not environmentally friendly, so there is need for harmless insecticides from bio-sources. The present work is therefore aimed at studying the adsorption of M. charantia leaf extract (EL) on a clay/arabic gum composite. Two composite samples containing clay/arabic gum of 2.5 g/7.5 g noted CP1 and 2.5 g/15 g noted CP2 were each prepared and characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM). Results show that the clay used is of the Kaolinite (kao) type. Arabic gum made it possible to increase the interlayer spaces of kao of the order of 2θ of 12.16° to 2θ of 7.25° and 6.60° for composite 1 (CP1) and composite 2 (CP2) respectively. Results best fitted Freundlich isotherm model for all the adsorbents with CP2 having better adsorption capacity of 9.05 (mg/g)(L/mg)1/n compared to 5.32 and 5.65 (mg/g)(L/mg)1/n for CP1 and kao respectively. The adsorption process was exothermic, non-spontaneous and occurred by physisorption mechanism. The pseudo-second-order kinetic model best fitted the experimental data for the samples with adsorption occurring faster on CP1 (0.20 g/mg/min) compared to kao (0.06 g/mg/min) and CP1 (0.04 g/mg/min). Results show that arabic gum composite with increasing mass of the arabic gum is more effective in binding M. charantia leaf extract. The arabic gum composite with adsorbed M. charantia leaf extract could be used as an insecticide powder for the preservation of foodstuffs