The quite efficient adsorption of methylene blue dye from an aqueous solution by graphene oxide was studied. The favorable electrostatic attraction is the main interaction between methylene blue and graphene oxide. As graphene oxide has the special nanostructural properties and negatively charged surface, the positively charged methylene blue molecules can be easily adsorbed on it. In the aqueous solution of methylene blue at 293 K, the adsorption data could be fitted by the Langmuir equation with a maximum adsorption amount of 1.939 mg/mg and a Langmuir adsorption equilibrium constant of 18.486 mL/mg. The adsorption amount increased with the increase of the solution pH (3-11), was not affected significantly by KCl under the examined condition and the adsorption process was exothermic in nature. The fast and considerable adsorption of graphene oxide could be regarded as a potential adsorbent for cationic dye removal in wastewater treatment process.

Quantum-confined Bi structures (quantum wells and quantum wires) are currently being studied for their varies novel properties. We now pursue the next level of quantum confinement in bismuth, quantum dots. In this work, we present a technique for the synthesis of bismuth nanoparticles using an inverse microemulsion method. To prevent air-oxidation in the characterization stage, poly(vinylpyrrolidone) was used as protecting agent. Our characterizations reveal that single rhombohedral phase of bismuth can be formed with ultrafine particle in size by following this synthetic route. The optical absorption spectrum of the aqueous nanoparticle colloids shows an absorption band centered at ~268 nm.

Poly(acrylic acid) (PAA) coated-Fe3O4 superparamagnetic nano-composites were synthesized through a solvothermal technique by using cheap and environmental friendly iron salts and PAA. Each nano-composite was composed of many small primary nanocrystals. The as-synthesized products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential scanning calorimetry (TG-DSC) analysis and nitrogen adsorption-desorption measurements. These nano-composites showed rapid adsorption rate and super removal capacity of cation organic dye methylene blue (MB). Moreover, the MB desorption could be easily performed using methanol and acetic acid mixed solution. The reused performance of the nano-composites was also studied.

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