Synthesis, characterization and applications of polyphenol-Fe(III) complexes and tannic acid resin

Valonia tannin extract (Valex) is a kind of typical hydrolysable tannin which is naturally and widely grown in the western Anatolian region in Turkey especially in Salihli. In the first part of the study, Fe(III)-Valex and Fe(III)-Tannic acid complexes were synthesized and used for comparison purposes. Also, complexes were characterized by using: Magnetic susceptibility, Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), Electron spin resonance (ESR), Matrix-assisted laser desorption/ionization-time-of-flight mass spectroscopy (MALDI-TOF MS), X-ray photoelectron spectroscopy (XPS) and Proton nuclear magnetic resonance spectroscopy (1H-NMR) analysis methods.Stability constants and Stoichiometries of complexes were determined at pH=2.4, 4.4, 6.4 and 8.4 by using Slope and Mole Ratio methods. Antioxidant and antimicrobial activity of complexes have been made for the application. Their antioxidant activities were determined based on the in vitro radical scavenging activity of 2,2-Diphenyl-1-picrylhydrazyl. The antimicrobial activitity of complexes were also determined by the in vitro disc diffusion method. Complexes were found to have antioxidant activity but did not show any antimicrobial activity.In the second part of the study, TA resin was synthesized and characterized. Application of TR was done with removal of boron by the boron adsorption as a function of contact time, temperature, initial boron concentration, pH and adsorbent dosage. TR was characterized by using FTIR, TGA, SEM (Scanning electron microscopy) and B.E.T. surface area analysis. The optimum adsorption conditions were found as 24 h, 308 K, 4 mgL-1 boron, pH=7.0 and 0.1g TR. The adsorption data was well suited to Langmuir equation. Monolayer adsorption capacity was calculated as 2.56 mgg-1.The pseudo-second-order equation which indicated chemical adsorption provided the best correlation for the adsorption process. Thermodynamic parameters, standard free energy (?Go), enthalpy change (?Ho) and entropy change (?So) were calculated. ?Go was turned out to be negative whereas ?Ho was positive. Percent of adsorption yield and desorption yield with 0.01M HCl was calculated as 88 and 81, respectively.