A new alternative adsorbent for the removal of cationic dyes from aqueous solution

Adsorption of Malachite green (MG) and Methylene blue (MB) from aqueous solutions on low cost adsorbent prepared from Annona squmosa seed (CAS) is studied experimentally. Results obtained indicate that the removal efficiency of Malachite green and Methylene blue at 27 ± 2 °C exceeds 75.66% and 24.33% respectively, and that the adsorption process is highly pH-dependent. Results showed that the optimum pH for dye removal is 6.0. The amount of dye adsorbed from aqueous solution increases with the increase of the initial dye concentration. Smaller adsorbent particle adds to increase the percentage removal of Malachite green and Methylene blue. The equilibrium data fitted well to the Langmuir model (R2 > 0.97) and the adsorption kinetic followed the pseudo-second-order equation (R2 > 0.99). The maximum adsorption capacities of MG, MB on CAS are 25.91 mg g−1 and 08.52 mg g−1 respectively. These results suggest that A. squmosa seed is a potential low-cost adsorbent for the dye removal from industrial wastewater. The adsorption capacity of CAS on MG is greater than MB.