Removal of estrogen pollutants using biochar-pellet-supported nanoscale zero-valent iron

Nanoscale zero-valent iron-supported biochar pellets (Nano zero-valent iron (nZVI)-biochar pellets (BP)) were synthesized via liquid-phase reduction and applied to estrogen removal, including estrone (E1), 17 beta-estradiol (E2), and estriol (E3). The performance of nZVI-BP, with respect to its characterization, removal kinetics, and isotherms, was investigated. The results showed that the adsorption equilibrium was reached within 10 min of exposure. The adsorption capacity of estrogen decreased with increasing solute pH and nZVI-BP dosage. The adsorptivity increased with increasing initial estrogen concentration. The estrogen behavior followed a pseudo-second-order kinetic model. The adsorption data of different initial estrogen concentrations fitted to Freundlich adsorption isotherms. In addition, a preliminarily discussion of the adsorption mechanism of nZVI-BP for estrogens was provided.