Robust Taguchi Optimization of Activated Carbon Preparation from Phragmites australis for Bisphenol A Adsorption

Abstract

The robust Taguchi method was used to optimize the preparation of activated carbon by microwave radiation from the agricultural waste Phragmites australis. The potential for removing endocrine disrupting compounds such as bisphenol A from aqueous solutions was explored. Results obtained by using Taguchi orthogonal design indicated that the optimal conditions for P. australis activated carbon, as determined based on the signal-to-noise ratio, were as follows: radiation power, 600 W; radiation time, 20 min; impregnation ratio, 1:1; impregnation time, 24 h; and mass fraction, 70% H₃PO₄. The heterogeneous surface structural morphology and multifarious functional groups of P. australis activated carbon were characterized by scanning electron microscopy, the Brunauer–Emmett–Teller method, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. In addition, the adsorption kinetic and isotherm experimental data of bisphenol A on P. australis activated carbon could be well fitted with pseudo-second-order kinetic (R² = 0.9966–0.9991) and Freundlich isotherm (R² = 0.9939–0.9982) models, respectively. The maximum adsorption capacity of P. australis activated carbon was 181.82 mg/g at 20°C. On the basis of the characterization and model analyses, the adsorption mechanism of bisphenol A on P. australis activated carbon may contribute to H-bonding, hydrophobic effects, and π–π interaction.