Extraction and optimization of tannin from the flower of Musa sp. applied to the treatment of iron ore dump

This work studies low-cost coagulants and flocculants with satisfactory efficiency, using the flower from Musa sp. as raw material. Many coagulants already used in the market, have high application cost and they may also be polluters. The tannins, natural biocoagulants, coming from the secondary mechanism of plants, are somewhat chemically reactive and they have already been used in processes. The present work has the objective of obtaining tannins using hot percolation as the extraction method, with the following factors: extraction solvent type, batch extraction number and percolation time. To evaluate the best extraction condition, a response surface methodology characterized by a Central Composite Design (CCD) was used, which could analyze each of the respective factors in five levels. The optimization of the model generated from the response surface aiming at a higher concentration of tannins was done using the Generalized Reduced Gradient (GRG) algorithm. Under these conditions, the tannin concentration was 0.93 μg/mL in the experimental conditions defined by the following factors: acetic acid solution 12.5% v/v, 6 batch with 45 min each. Under these conditions, the efficiency of the extract in the coagulation and flocculation of sludge from the mining industry was 98.78% for turbidity removal and 99.24% for solid removal.