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 (V mic/V tot) 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.

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A combined process coupling photocatalysis and a biological treatment was investigated for the removal of Bezacryl yellow (BZY), an industrial-use textile dye. Photocatalytic degradation experiments of BZY were carried out in two stirred reactors, operating in batch mode with internal or external irradiation. Two photocatalysts (TiO2P25 and TiO2PC500) were tested and the dye degradation was studied for different initial pollutant concentrations (10-117 mg L(-1)). A comparative study showed that the photocatalytic degradation led to the highest degradation and mineralization yields in a stirred reactor with internal irradiation in the presence of the P25 catalyst. Regardless of the photocatalyst, discoloration yields up to 99% were obtained for 10 and 20 mg L(-1) dye concentrations in the reactor with internal irradiation. Moreover, the first-order kinetic and Langmuir-Hinshelwood models were examined by using the nonlinear method for different initial concentrations and showed that the two models lead to completely different predicted kinetics suggesting that they were completely different.According to the BOD5/ Chemical oxygen demand (COD) ratio, the non-treated solution (20 mg L(-1) of BZY) was estimated as non-biodegradable. After photocatalytic pretreatment of bezacryl solution containing 20 mg/L of initial dye, the biodegradability test showed a BOD5/COD ratio of 0.5, which is above the limit of biodegradability (0.4). These results were promising regarding the feasibility of combining photocatalysis and biological mineralization for the removal of BZY.