Adsorption of organophosphorus malathion pesticide from aqueous solutions using nano-polypropylene-titanium dioxide composite: Equilibrium, kinetics and Optimization studies.

Abstract

The purpose of this study was to investigate the applicability of the adsorption process of a persistent organophosphorus pesticide (malathion) from aqueous solutions by using titanium dioxide- polypropylene nanocomposite (Nano-PP/TiO2). The structure of Nano-PP/TiO2 was specified by field emission scanning electron microscopes (FE-SEM), fourier-transform infrared spectroscopy (FTIR), brunauer-emmett-teller (BET), and transmission electron microscope (TEM) technologies. Response surface methodology (RSM) was applied to optimize the adsorption of malathion onto Nano-PP/TiO2 and investigates the effects of various experimental parameters including contact time (5-60min), adsorbent dose (0.5-4g/l) and initial malathion concentration (5-20000mg/l). Extraction and analysis of malathion were performed by dispersive liquid-liquid microextraction (DLLME) coupled with a gas chromatography, coupled with flame ionization detector (GC/FID). The isotherms obtained for Nano-PP/TiO2 revealed that it was a mesoporous material with a total pore volume of 2.06 cm3/g, average pore diameters of 2.48nm and a surface area of 51.52 m2/g. The obtained results showed that the Langmuir type 2 was the best-fitted model for delegating the equilibrium data of isotherm studies with adsorption capacity of 7.43mg/g, and pseudo-second-order type 1 for kinetic model. The optimized conditions to achieve the maximum removal (96%) were at a malathion concentration of 7.13mg/L, contact time of 52min and adsorbent dose of 0.5g/L. Due to its efficient and appropriate function in adsorbing malathion from aqueous solutions, it was revealed that Nano-PP/TiO2 can be used as an effective adsorbent as well as in further studies.