Adsorption of Reactive Red 2 using activated carbon prepared from walnut shell: batch and fixed bed studies

The preparation of activated carbon from walnut shell with ZnCl2 activation and its ability to remove Reactive Red 2 from aqueous solutions was studied through batch and column study. The adsorbent was characterized with BET, FTIR, and SEM. Batch-adsorption technique was conducted to investigate the effects of parameters namely; pH, absorbent dose, contact time, and initial dye concentration on the adsorption efficiency. In column study, the effects of initial dye concentration, bed height and flow rate on Reactive Red 2 (RR2) adsorption were studied. In batch system, the adsorption efficiency at a dose of 1.5 g/L and pH 2 was achieved by 65.55%. Data were fitted with Langmuir isotherm equilibrium. The maximum capacity based on Langmuir model was 81.3 mg/g. The results showed that by increasing the concentration of color on continuous input from 50 to 150 mg/L the adsorption capacity has increased from 42.18 to 53.72 mg/g, respectively. With the increase in height of column from 2 to 8 cm the adsorption capacity increased from 37.28 to 54.61 mg/g. Furthermore, with increases of flow rate from 5 to 15 ml/min the adsorption capacity decreased from 51.81 to36.67 mg/g.