Carbon Spheres for the Removal of Hevay Metal Ions From Refinery Effluents

Abstract

An environmentally-friendly hydrothermal procedure was employed to synthesize carbon spheres (CS) from glucose solution at 1700C. To study the effect of reaction time, four CS samples were synthesized at 12h, 14h, 16h and 19h, respectively. A portion of the samples were surface activated by the treatment with 0.5M NaOH, the other portion treated with 0.5M CH3COOH, and the remaining samples were left untreated (native). All samples were characterized using various methods including SEM, XRD, Raman spectroscopy, N2 adsorption and FT-IR. Batch adsorption experiments were carried out at room temperature to remove heavy metal ions (Ag+ and Cu2+) from aqueous solution. It was found that increasing reaction time resulted in CS with a lower amorphous content and lowered adsorption capacity, NaOH-treated CS had the highest adsorption capacity of 454 mg Ag+/g and 172 mg Cu2+/g, while CH3COOH-treated CS had a lower Ag+ and Cu2+ uptake than untreated CS. The adsorption isotherms were well fit by the Langmuir isotherm equation (for base-treated CS) and the Freundlich isotherm equation (for acid-treated CS). The CS showed a high potential for the removal of heavy-metals from aqueous solutions.