Modified tannins and their application in wastewater treatment

Abstract

The bio-flocculants used in this study were synthesised by the Mannich reaction, which includes three reagents: a substrate (tannin extracts of Acacia, Quebracho, and Castanea), formaldehyde, and an amine derivative (ethanolamine, diethanolamine, ammonium chloride). Nine natural flocculants were prepared by combining extracts and amines; these products were evaluated in three different wastewater samples in two experimental phases. In phase I, five physicochemical parameters were analysed. From the data obtained, a multivariate, completely randomised design (CRD-Manava) was used, with a factorial arrangement and mean plots. In phase II, the three bio-flocculants with the most statistically significant responses and their mixtures were examined, evaluating 14 biological and physicochemical parameters. Statistical analysis was guided in this phase by CRD blocks, finding a significant removal in the physicochemical parameters analysed in the different types of wastewater and obtaining removal rates between 50 and 90%, depending on the parameter. At the end of both phases, the bio-flocculants acacia-ammonium chloride and quebracho-diethanolamine were the most efficient in the removal of turbidity (34–99%), true colour (93–100%) and total solids (12–99%). In addition, the natural flocculants showed low mutagenicity index (MI: 0.33–0.93) compared to aluminium sulphate (MI: 4.87–8.81).

Life‐cycle assessment of the production of cationized tannins from Norway spruce bark as flocculants in wastewater treatment

“…27 Tannins can be grafted in many ways to achieve the properties required for different applications. 28 A common way to introduce cationic properties to tannins is by adding a protonated tertiary nitrogen through a Mannich reaction [29][30][31][32][33] as shown in Fig. 4.…”

Study of the anticorrosive properties of “quebracho colorado” extract and its use in a primer for aluminum1050

“…The FTIR spectrum of the "quebracho colorado" extract is showed on Fig. 2, and the assignment of each band is resumed on Table 3 [6,[50][51][52][53][54]. The 1283 cm −1 strong band is a characteristic feature for the flavonoid-based tannins, and can be assigned to the ethereal CeO asymmetric stretching vibration arising from the pyran-derived ring structure of this class of tannins.…”

Implementation of Modified Acacia Tannin by Mannich Reaction for Removal of Heavy Metals (Cu, Cr and Hg)

“…The modification of the tannin was carried out by the Mannich reaction using ammonium chloride and formaldehyde under conditions previously standardized in the laboratory [6,8], see Figure 1. Two solutions were prepared: (i) 10.5 mL of distilled water was added to 8.66 g of the Acacia tannic extract at a temperature of 65 °C and with constant agitation until a homogeneous mixture was obtained.…”

“…Besides, they can be classified as hydrolyzable (gallotannins, ellagitannins) and nonhydrolyzables. These substances are currently investigated as coagulant-flocculating agents and for cationic potentiation by the Mannich reaction as a consequence of the reaction between an aldehyde and an amine compound, generating the addition of the carboxyl groups and aminos to the tannin structure [6,7]. The objective of the present work was to determine if the modified Acacia tannin could remove copper, chromium and mercury metals when employing the coagulation-flocculation process in industrial wastewater.…”