From waste to resource: yeast residues valorized into nanomodified activated carbon for endocrine disruptor removal

The continuous release of endocrine-disrupting hormones into aquatic environments has become an emerging environmental concern due to their persistence and potential ecotoxicological effects, even at low concentrations. Conventional water treatment processes are often insufficient for the complete removal of these substances, highlighting the need for more efficient and sustainable alternatives. In this study, a magnetic nanocomposite adsorbent based on yeast-derived activated carbon (YAC-MNP) was developed and evaluated for the removal of estrone (E1) and progesterone (PROG) from aqueous solutions. YAC-MNP was synthesized via chemical activation followed by incorporation of magnetite (Fe₃O₄) nanoparticles, enabling magnetic recovery after treatment. Batch adsorption experiments were performed, and the point of zero charge (pH_PZC) was determined as 6.05. The adsorption performance remained stable under acidic conditions (pH 2-6), with no significant variation in sorption capacity, which ranged from 16 to 18 mg/g for E1 and from 11 to 13 mg/g for PROG. Kinetic studies showed rapid adsorption, with equilibrium reached within 30 min for E1 and 90 min for PROG, and the data were best described by the pseudo-second-order model. Equilibrium isotherms were better fitted by models that assume heterogeneous surfaces, such as Hill and Toth, indicating non-uniform adsorption sites. Adsorption efficiency was also assessed using spiked lake water to simulate a more complex matrix, achieving removal efficiency of 67%. Overall, the results demonstrate that YAC-MNP is a promising, low-cost, and magnetically recoverable biosorbent for the removal of hormones from water.