Malachite green adsorption by calcium-rich crab shell char via two-stage adsorber design

The present work was aimed to evaluate the optimum mass of crab shell biochar and adsorption contact time in a two-stage adsorber design for malachite green. The model was developed to predict optimum adsorbent mass and adsorption profiles at specified volumes and concentrations of dye effluent. Results show that the adsorbent mass can only be reduced by 1.91 % because of the adsorbent’s strong affinity towards malachite green. Accordingly, the adsorption contact time to achieve equilibrium has dramatically reduced from 150 min to 31 min. In the performance evaluation, the adsorbent mass in stage-1 is always higher than that in stage-2 to subside the adsorbent load in achieving the target removal at optimum dosage. From the response surface methodology, the most significant parameters in two-stage adsorber design are adsorption time at stage-2 and malachite green concentration. The predicted values of adsorbent mass and time are essential in designing the cost-competitive two-stage adsorption process for industrial wastewater treatment.