Production of vegetable cationic coagulant from eucalyptus bark (Eucalyptus tereticornis)

Abstract

The tannins appear as substitutes of aluminum salts in water treatment by the difficulty of sludge disposal. Eucalyptus appears as an unusual alternative for the tannin obtainment. The tannin concentration in the bark is bigger than in other parts of the tree. The Mannich reaction is a synthesis reaction to add the charge to the tannin. The objective of this work was to produce a vegetable cationic coagulant from eucalyptus (Eucalyptus tereticornis) bark. The shells samples were collected with 5 cm of thickness from 1,30 m above the soil from individuals of six years old. The extraction was made with ethanol and water by variation of extraction time from six days to eleven days. The extraction time was chosen by obtaining the highest concentration of condensed tannin. The temperature range that achieved the lowest reaction time for the first stage of the Mannich reaction was determinated. The cationic coagulant was produced in the experiment conditions which was characterized physico-chemically. The enlargement of extraction time increases the concentration of condensed tannins in the extract from the bark of Eucalyptus tereticornis. The higher temperatures accelerate the first step of the Mannich reaction. The product formed using eleven days extraction in water and the temperature of the first stage of the Mannich reaction between 91°C to 100ºC, has a total solids of 0.597 %.