Batch and continuous processes for the removal of Al3+ and Fe2+ from aqueous effluents using spent coffee ground
Processos batch e contínuo para a remoção de Al3+ e Fe2+ de efluentes aquosos utilizando café moído
Keywords:coffee, sorption, metal ions, isotherm, kinetics
Due to the intense industrialization of the modern society, severe contamination of water by dangerous metal ions has become a major problem. The use of plant-derived biosorbents has been proposed in different studies in reason of their good performance and marginal cost. The proposal of this study was to evaluate the use of spent coffee ground (SCG) for the removal of metal ions from aqueous effluents. The batch process showed removal efficiencies equal to 92.4% for Al3+ and 85.9% for Fe2+, and the continuous process showed removal efficiencies equal to 97.2% for Al3+ and 96.2% for Fe2+. These two processes were compared using Freundlich and Langmuir models, and Langmuir-3 model showed the best adequacy for all processes indicating to be favorable (0.12 ≤ RL ≤ 0.59), with equilibrium sorption capacities between 1.79 and 4.21 mg/g SCG. Kinetic evaluations suggested that these two processes follow a pseudo-second order model for both ions, with thermodynamically favorable characteristics. All data indicated that this biosorbent has a good potential to be used for the removal of metal ions from contaminated aqueous effluents.