Preparation and optimization of novel graphene oxide and adsorption isotherm study of methylene blue

Abstract

Graphene oxide (GO) with high oxidation degree (OD) and high adsorption capacity was synthesized easily by modified improved hummer method assisted with ultrasonic at low temperature and short time. Optimization of the synthesis procedure was performed using the response surface method (RSM). Effects of synthesis variables such as Ultrasonic temperature (°C), Ultrasonic time (min) and the time of adding oxidizing agent (hr) on the oxidation degree were studied. Optimum condition to maximize the oxidation degree was determined as follows: Ultrasonic temperature of 30.8 (°C), Ultrasonic time of 47.5 (min) and the time of adding oxidizing agent of 3 (hr). Synthesized GO characterized by UV–Vis spectroscopy, X-ray diffraction, Fourier transform infrared spectrometry, Thermogravimetric analysis, Field emission scanning electron microscopy and BET to study the surface morphology. The adsorption capacity of the synthesized GO was investigated using methylene blue (MB) adsorption that showed a high adsorption capacity of 1635 mg/gr. The adsorption isotherm of MB on the GO was investigated experimentally and mathematically. Experimental data fitted by Langmuir equation with a R2 of 0.9975 and a Langmuir adsorption equilibrium constant of 0.09375 (L/mg).