Preparation and Characterization of Carbons from Coffee Residue: Adsorption of Salicylic Acid on the Prepared Carbons

Abstract

Five activated carbons were prepared at 600 °C from coffee residue by chemical activation using ZnCl2. The effects of the impregnation ratio (ZnCl2/coffee residue) varying from (0 to 100) % on the physical and chemical characteristics were studied. Characterization of these samples was performed by using thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption−desorption isotherms at 77 K. Results showed that the microporosity (Vmic/Vtot) presented by the activated carbon at 25 % was more important with 95.70 %, while the other results indicated (92.33, 81.55, and 70.04) % for the rest of activated carbons prepared with activation ratios of (50, 75, and 100) %, respectively. Other physical and chemical characteristics such as pHPZC, apparent and real density, and so forth were also determined to complete the characterization. All of the prepared carbons were subjected to the adsorption of salicylic acid. The obtained results showed that the adsorption of salicylic acid is more effective onto activated carbon prepared with 25 % of ZnCl2 (AC 25 %). Consequently, the results of this study show that the coffee residue can be converted into activated carbon with desired characteristics by a judicious choice of activation ratio.