Adsorption of methylene blue by Nicandra physaloides(L.) Gaertn seed gum / grapheme oxide aerogel.

In this study, a novel composite aerogel of Nicandra physaloides(L.) Gaertn seed, gum/graphene oxide (NPG/GO), was prepared by using a vacuum freeze drying method for methylene blue (MB) adsorption. The techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), were adopted for studying the structure and surface characteristics of NPG/GO, with thermogravimetric analysis (TGA) being adopted for testing thermal properties. The effects of pH value, initial dye concentration, temperature and adsorbent dosage on adsorption performance were elaborately analysed. The adsorption kinetic studies showed that the process of adsorption follows Langmuir isotherm and a pseudo-second-order kinetic model. When the mass ratio of NPG to GO was 1.25:1, the adsorption capacity was the highest. According to Langmuir isotherm, the maximum adsorption capacity of 408.16 mg/g was higher than that of NPG. The specific surface area and average pore diameter of NPG/GO was measured as 2.70 m2/g and 4.8 nm, respectively. Thermodynamic analysis revealed that the adsorption process of methylene blue on NPG/GO was a spontaneous and endothermic process. In general, the prepared nanocomposites were excellent candidates for adsorption and removal process because of simple synthesis, low cost, high efficiency, non-toxicity, environment protection and degradability.