Behavior and Mechanism of Tannic Acid Adsorption on the Calcite Surface: Isothermal, Kinetic, and Thermodynamic Studies

Abstract

Tannic acid is a calcite flotation agent widely used in mineral processing. To better understand the physicochemical reactivity of tannic acid toward calcite, the present work focused on studying the mechanisms involved during the adsorption process. Hence, in order to determine the optimal physicochemical parameters, tannic acid adsorption onto calcite was investigated at various experimental conditions such as contact time, initial tannic acid concentration, solution pH, particle size, and temperature. The obtained results showed that the adsorption capacity of tannic acid increased significantly with initial tannic acid concentration. Furthermore, tannic acid adsorption onto calcite was highly dependent on solution pH, and the optimal adsorption amount was found to be at pH 8. Therefore, the behavior controlling the studied adsorption process could be attributed to ion exchange. Moreover, the adsorption mechanism has been determined by isothermal, kinetic, and thermodynamic studies. Thus, the Sips isotherm model was the one that best predicted equilibrium data. Adsorption kinetics followed a pseudo-second-order model, indicating that the adsorption process was controlled by the chemical reaction. The estimated thermodynamic parameters revealed that the adsorption reaction was exothermic in nature and the system entropy decreased nonsignificantly during this process. Based on these results, the study of the physicochemical interaction between tannins and carbonates has potential application in mineral processing as well as in other fields.

Multifunctional Ionic Skin with Sensing, UV‐Filtering, Water‐Retaining, and Anti‐Freezing Capabilities

“…[ 32 ] In addition, TA@HAP NWs have phenolic‐OH groups and –OH groups of hydroxyapatite in the range of 3600–3000 cm −1 . [ 31b,32,33 ] All these peaks show that TA has been successfully wrapped on HAP NWs. Next, TA@HAP NWs, PVA and AlCl 3 powder were added to the pre‐prepared binary solvent of EG and water, and stirred at 95 °C for 4 h. AlCl 3 can be completely ionized in water, but not in EG, which helps Al 3+ move freely in the molecular level ion water channel separated by EG molecules.…”

Rapid construction of hierarchically porous metal–organic frameworks by a spray‐drying strategy for enhanced tannic acid adsorption

“…To better demonstrate the excellent adsorption properties of HP-MIL-101, a more comprehensive comparison of the rate constant and adsorption capacity for the removal of TA with other materials reported in the literature is given in Table 3. 32,[37][38][39][40][41][42][43][44] It can be clearly seen that HP-MIL-101-30 displays a much higher adsorption rate than most reported materials at the same or even lower adsorbent dosage/TA concentration.…”

The behaviour of tannic acid adsorption on fluorite surface: Isotherm, kinetic and thermodynamic studies

“…The preparation and characterization of commercial tannic acid used as an adsorbate has been deeply described in our previous studies (Tangarfa et al, 2019;Tangarfa et al, 2021). 10 g/L of tannic acid stock solution was prepared and diluated to desired concentrations for further experiments.…”

“…Therefore, there is a paucity of literature regarding methods to evaluate the adsorption mechanism. In our previous works (Tangarfa et al, 2019;Tangarfa et al, 2021), tannic acid adsorption behavior onto calcite has been deeply examined conducting out isotherm, kinetic and thermodynamic studies as well as optimization response surface methodology. Obtained results showed that ion exchange reaction occurs between tannic acid phenolic groups and calcium ions onto calcite.…”