Magnetic chitosan graphene oxide composite for solid phase extraction of phenylurea herbicides

Magnetic chitosan graphene oxide composite was successfully prepared and used as an adsorbent for the simultaneous removal and extraction of three phenylurea herbicides monuron, linuron and isoproturon and determined using high performance liquid chromatography with UV detector. The composition and morphology of the composite was studied through Fourier transformed infrared spectroscopy, Scanning electron microscopy, Energy dispersive X-ray and X-ray diffraction analysis. Several factors such as pH of solution, adsorption time, temperature, kinetics and isotherms were studied. The maximum adsorption capacity was 35.71 mg/g for monuron, 33.33 mg/g for linuron and 29.41 mg/g for isoproturon at room temperature and pH 5. The adsorption process best fitted to pseudo second order kinetics and Langmuir adsorption isotherm. Thermodynamic study suggested exothermic and spontaneous adsorption process. The % recoveries for linuron, monuron and isoproturon were 94.09% +/- 2.68, 92.37% +/- 1.14 and 90.32% +/- 1.23 respectively. The proposed method was successfully applied to spiked samples of rice and river Kabul water.