Preparation of mono-dispersed carbonaceous spheres via a hydrothermal process

- pH value showed an evident effect on the morphology of carbonaceous spheres (CS).
- CS could be obtained when the pH value of starting solution is less than 12.
- Lumpy aggregation of CS were formed when pH value was 13-14.
- The CS prepared under pH 6, 9 showed good adsorption capacity for MB.

Mono-dispersed carbonaceous spheres (CS) with a narrow size distribution were synthesized via hydrothermal treatment of glucose. The effects of hydrothermal temperature and time, glucose concentration and pH value of solution were investigated in detail. Structures and surface properties of as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Induced coupled plasma emission spectroscopy (ICP), thermogravimetric analysis/differential scanning calorimetry (TG/DSC), Nitrogen adsorption/desorption and Fourier transformed infrared spectroscopy (FTIR). The results showed that the production yield of CS increased from 2.1 to 32% with increasing the temperature from 160 to 180 °C, and the average size increased from 0.23 to 0.95 μm with extending the hydrothermal time from 8 to 16 h. pH value of the starting solution showed an evident effect on the morphology of CS via affecting the decomposition products of glucose. CS could be obtained when the pH value of starting solution was less than 12, but further increasing the pH value to 13-14 led to the formation of lumpy aggregations of carbon rather than spherical CS. The CS prepared under pH 6 and 9 showed good adsorption capacity for Methylene blue (MB), which was attributed to their relatively high specific surface area.

CS with size of about 1.0 μm were synthesized via a hydrothermal process using glucose as a starting material. The solution pH value showed an evident effect on the morphology of CS. Spherical CS could be obtained at pH value of solution less than 12, otherwise, lumpy aggregations of carbon rather than spherical CS were formed. In addition, CS prepared at pH 6 and 9 showed good adsorption capacity for Methylene blue (MB).54