Comparative study on removal of two basic dyes in aqueous medium by adsorption using activated carbon from Ziziphus lotus stones

Abstract The objective of this research work concerns the adsorption of two cationic textile dyes namely Basic Yellow 28 (BY28) and Basic Red 46 (BR46) from synthetic water was investigated on new activated carbon. It was elaborated from Ziziphus lotus stones (ACZLS) activated by H 3 PO 4 with an impregnation ratio (H 3 PO 4 mass/precursor mass) equal to 2. In batch configuration, the effects of experimental parameters, such as contact time (0–180 min), pH (2−10), ACZLS dose (0.2–0.7 g L −1 ) and initial dye concentration (80–250 mg L −1 ) on the removal percentage were studied. Among the various isotherms, the results indicate that the Langmuir model was the most appropriate for fitting the equilibrium data with the highest correlation coefficient (R 2  = 0.99). The maximum adsorption capacities were found to be 424 and 307 mg g −1 for BY28 and BR46 respectively at 20 °C and pH ~ 8. In addition, the kinetic of the two dyes removal shows that the experimental data are well fitted by the pseudo 2nd order rate equation (R 2  = 0.99) and the intraparticle diffusion study revealed that the adsorption process was not controlled by the intraparticle diffusion step (C ≠ 0). In conclusion, the overall results suggest that this low cost activated carbon obtained from environmentally friendly Ziziphus lotus stones may be useful for the depollution of wastewaters loaded with cationic dyes.