Single and multi-component removal of natural hormones from aqueous solutions using soybean hull

Abstract

The presence of natural hormones in water resources has gained considerable attention in recent years due to their capacity to cause imbalances in several biological systems. Studies have shown that estrone (E1), 17β-estradiol (E2), and estriol (E3) have a high contamination potential even in low concentrations. Thus, new methods are needed to remove these contaminants directly at the source. The present study evaluated the use of the in natura soybean hull as a biosorbent for the removal of estrone (E1), 17β-estradiol (E2), and estriol (E3) from swine manure, using single and multi-component systems. Best hormone removal conditions were performed at room temperature (25 °C) with no pH adjustment. Equilibrium for a single component (SC) and multi-component (MC) systems was reached in 1 h for E1 and 2 h for E2 and E3, and the kinetics were well described by the pseudo-first-order model. Ternary equilibrium models indicated that there was no competition among the hormones. For the MC system, Langmuir model showed maximum adsorption capacities of 2.560 mg g−1, 1.978 mg g−1 and 0.835 mg g−1 for E1, E2, and E3, respectively. Thermodynamic analysis indicated that the adsorption was favorable and spontaneous with physisorption characteristics. The hydrogen-bonding represented the primary adsorption mechanism between the hormones and the adsorbent. The in natura soybean hulls, used as an adsorbent, showed to be promising for removing hormones present in the biofertilizer (swine manure), with characteristics that allow the adsorbent to remain together with the biofertilizer at its final destination. Therefore, an environmentally friendly technology.