Desenvolvimento de um coagulante orgânico catiônico preparado com extrato de Minosa tenuiflora para tratamento de água

Abstract

One of the main problems in water treatment is related to the use of aluminum salt based coagulants that generates a toxic sludge which can cause neurological diseases such as Parkinson’s and Alzheimer’s. One of the promising alternatives to alleviate this problem is the substitution of vegetable coagulants. Among the various plant species, Mimosa tenuiflora, commonly known as Jurema-preta, is the most abundant species in the Brazilian semiarid and has a major producer of tannin for use in the industrial setor. In this context, this research the main objective is to develop a vegetable-based coagulant based on tannin, of Mimosa tenuiflora barks for use in the treatment of water. For this, a preliminary study was carried out to determine the best extraction conditions of these compounds, through a 2^3 complete factorial design with three repetitions at the central points, varying the time (60, 90 and 120 minutes), temperature (60 , 80 and 100°C) and aqueous sodium sulfite concentration (0, 2.5 and 5%), with TST, TTC, TNT and NS as the response variables. The best condition of factorial planning for tannin extraction was observed in trial 4, which obtained 22.04% TTC with a purity of 90.14%. This extract was characterized by TLC and FTIR and used for the production of the cationic coagulant, via Mannich reaction. The coagulant obtained was characterized by spectroscopy in the infrared region and the application of this by Jar-Test, with dosages ranging from 30-80 mg/L and of sedimentation of 1.5 and 3.0 cm.min^-1 , for this, water samples from the reservoirs were used of Bodocongó and Gavião of the cities of Campina Grande-PB and Fagundes-Pb, respectively. The best result was with the velocity of 1.5 cm.min^-1 and concentration of 50 mg/L for the water of the Bodocongó reservoir and 60 mg/L for the water of the Gavião reservoir. In the comparison with commercial coagulants, the coagulant developed from Mimosa tenuiflora (TN-JP) peels obtained better performance than inorganic coagulant, aluminum sulphate, in all the tests and similar behavior with the organic (Tanfloc SL), favoring a removal of up to 95% of turbidity and 79% of apparent color in the analyzed waters, maintaining the pH with few changes and obeying the prevailing ordinance 2914/11 for standards of potability. Therefore, it was obtained from this a biotechnological innovation.