Thermal Decomposition and Kinetic Studies of Tannic Acid Using Model Free-Methods

Abstract

In this manuscript, thermal and kinetic features of a tannic acid was studied by simultaneous TG-DTA techniques in the nitrogen atmosphere at four heating rate. It was observed that thermal decomposition of its constituents occurred in two steps. Model free isoconversional methods namely modified Coast-Redfern (CR), Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Freidman (FR) were used for revelation of decomposition kinetics (E a and lnA) on the whole range of temperature. Mechanisms of decomposition process have been found to follow first order of decomposition rate. Reaction order does not have a substantial effect on the process because of the high value of pre-exponential factor. It was observed that, at the last stage of decomposition process, value of activation energy and pre-exponential factor increased. Decomposition of tannic acid was confirmed by IR spectroscopy.

Designing Hybrid Mesoporous Pr/Tannate-Inbuilt ZIF8-Decorated MoS2as Novel Nanoreservoirs toward Smart pH-Triggered Anti-corrosion/Robust Thermomechanical Epoxy Nanocoatings

“…For the TA-ZIF8@MS nanopowder, a 7.76% initial mass loss from 60 to 180 °C was detected due to a combination of evaporating the adsorbed water and many functional groups of OH available in TA, as well as the occurring preliminary oxidations, volatile fraction elimination, and thermal reforming of the TA chemical structure . The next major pyrolysis step (22.2% loss of mass) was sharper and more pronounced and occurred in the temperature range of 220–450 °C, which is similar to the TGA graph of the individual TA . This is certainly attributed to the hydrolysis or depolymerization of tannins.…”

“…40 The next major pyrolysis step (22.2% loss of mass) was sharper and more pronounced and occurred in the temperature range of 220−450 °C, which is similar to the TGA graph of the individual TA. 41 This is certainly attributed to the hydrolysis or depolymerization of tannins. From the obtained mass loss in this domain regarding TA degradation, a 22.2% efficiency of loading the TA into the ZIF8@MS nanosheet can be deduced.…”

Impact of roasting on the phenolic and volatile compounds in coffee beans

“…Suitable roasting could degrade condensed tannins into the lower molecular mass of flavonoids, such as anthocyanin, which could improve free TFC value to some extent. However, tannins perform high thermal resistance whose content could be slightly reduced with the temperature lower than 210°C (Ahmad et al, 2018;Van Cuong et al, 2014). Flavan-3-ol is the monomer of condensed tannins which belongs to flavonoids, whereas gallic acid is a component of hydrolyzable tannins belonging to nonflavonoids (Mehari et al, 2020).…”

In vitro digestion and colonic fermentation of phenolic compounds and their bioaccessibility from raw and roasted nut kernels

“…29 Additionally, compared to other phenolic compounds, tannins often have a higher heat resistance, which means that after roasting, some of the tannins may still be present. 38 As a result, the bioaccessibility of gallic acid, catechin, and epicatechin in the roasted nut kernels was comparatively higher in the gastrointestinal system. Similarly, Campos-Vega, Vázquez-Sánchez 29 discovered that during digestion and fermentation, the bioaccessibility of phenolic compounds, such as flavonoids and condensed tannins, was comparable in the spent nut grounds from medium- and dark-roasted nuts.…”

“…29 Additionally, compared to other phenolic compounds, tannins often have a higher heat resistance, which means that after roasting, some of the tannins may still be present. 38 As a result, the bioaccessibility of gallic acid, Nut samples mentioned in abbreviations are Roasted almond "RA"; Roasted cashew "RC"; Roasted walnut "RW". '-' shows that compound not detected during HPLC analysis while "0.00″ means bioaccessibility of compound is too low to quantify using equation.…”