Preparation and characterization of tannic acid resin: Study of boron adsorption

Abstract

Adsorption of boron from aqueous solutions onto tannic acid resin (TR) was investigated in this study as a function of contact time, temperature, initial boron concentration, pH, and adsorbent dosage. TR was prepared from commercial tannic acid by chemical activation with formaldehyde in aqueous ammonia and characterized by using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and BET surface area analysis. The optimum adsorption conditions were found as 24 h, 308 K, 4 mg L⁻¹, boron, pH = 7.0, and 0.1 g TR. The adsorption data was well suited to Langmuir equation. Monolayer adsorption capacity (Q_o) was calculated as 2.56 mg g⁻¹. The pseudo-second-order equation, which indicated chemical adsorption, provided the best correlation for the adsorption process. Thermodynamic parameters, such as standard free energy (ΔG^o), enthalpy change (ΔH^o), and entropy change (ΔS^o) were calculated. The thermodynamics of boron adsorption onto TR indicated spontaneous and endothermic nature. Adsorption yield was determined as 88% and then 81% of boron was desorbed with 0.01 M HCl. © 2012 American Institute of Chemical Engineers Environ Prog, 2012