Dissolution of condensed tannin with phenol: Optimum reaction parameters and some flow properties

Abstract

Condensed tannins from the bark of black wattle (Acacia mearnsii L.) were solubilized with phenol using HCl as a catalyst. The optimum reaction parameters (temperature, time, and acid concentration) of the dissolution were determined. The results showed a clear effect on the percentage of reacted phenol and residue tannin by temperature, time and, particularly, acid concentration. It was found that almost 77% of the phenol used could be reacted with the tannin, and about 90% of the tannin could be solubilized into phenol in the presence of HCl (as a catalyst) having a concentration of 5%. The optimum temperature, time, and acid concentration were 160°C, 90 min, and 4%-5%, respectively.

Dissolution of condensed tannin powder-based polyphenolic compound in water-glycerol-acid solution

“…The set parameters, namely mass of glycerol, mass of tannin powder, temperature, and stirring time were selected based on research conducted by Samil et al (2005) and Cardona and Sultan (2015). Samil et al (2005) investigated the dissolution of tannin in phenol, while Cardona and Sultan (2015) tested the dissolution of tannin in glycerol and used it for resin applications. The preliminary screening parameters are shown in Table 1.…”

“…Tannin powder has been traditionally dissolved in phenol for reactivation. Samil et al (2005) were able to dissolve 90% w/w of the condensed tannin in phenol with the presence of sulfuric and hydrochloric acids (4 to 5 %) at 160 °C. However, phenol is known for its toxicity and carcinogenic properties.…”

“…The presence of multiple hydroxyl groups in glycerol make it similar to water and simple aliphatic alcohols, such that it is categorized as a good solvent (Cardona and Sultan 2015). The reaction can be accelerated by the addition of an acid catalyst (Samil et al 2005;Cardona and Sultan 2015). The presence of hydroxyl groups on tannins allowed the formation of stable cross-linking between polyphenolic compounds with macromolecules such as polyols (glycerol) (Khanbabaee and van Ree 2001;Ashok and Upadhyaya 2012;Shrivastava et al 2017).…”

“…However, using a high amount of glycerol in dissolving tannin powder caused: 1) a reduction in the amount of tannin that could be dissolved, as shown by Cardona and Sultan (2015). Since, tannin is required to reduce the brittleness properties of phenol formaldehyde resin (Samil et al 2005;Jahanshaei et al 2012;Cardona and Sultan 2015), it is important to be able to increase the amount of tannin powder that could be dissolved in a solvent. 2) The produced dissolved tannin is highly viscous.…”

Use of peanut shell-based polyurethane type rigid foam in removing remazol orange RGB dye from aqueous solution

“…A similar result has also been found for RO-RGB adsorption on peanut shell. 26…”