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Evaluation of the 17-α-Ethinyl Estradiol Sorption Capacity in Soil

de Oliveira, Renan Angrizani, Tardelli, Edgard Robles, Jozala, Angela Faustino, Grotto, Denise
Water, air, and soil pollution 2019 v.230 no.4 pp. 85
adsorption, drugs, endocrine system, estradiol, high performance liquid chromatography, mathematical models, pH, soil, soil sampling, sorption isotherms, texture, vegetation, Brazil
17-α-Ethinyl estradiol (EE2) is a widely used drug that acts in the endocrine system and in the environment; even at low concentrations, it causes extensive damage to organisms. The most relevant factors for understanding the EE2 degradation and transport mechanisms in soil are through sorption studies. This study investigated the sorption capacity of EE2 in soil collected amidst vegetation in the region of Sorocaba, São Paulo state, Brazil. The soil samples were submitted to the evaluation of the physical-chemical parameters to characterization. The zero point of charge test (ZPC) was run using the adapted method of the 11-point model. Kinetic tests were then carried out, varying the removal times of the samples with fixed EE2 concentration, whereas, for the isotherm tests, the concentrations were varied, and the fixed contact time was maintained. The final concentrations of EE2 were quantified by high-performance liquid chromatography. Data treatments were carried out using mathematical modeling tests present in the literature. The soil presented a medium texture, being predominantly sandy, and the chemical parameters were classified as high and medium. Only the pH parameter was classified as low. The ZPC was 5.57, indicating an adsorption favorable to the EE2 that presented an average pH of 5.73. The adsorption kinetics showed that the equilibrium time for EE2 in contact with the soil is 12 h. The adsorption isotherm presented values related as favorable and adjustable to the Sips isotherm model and estimated the maximum adsorption capacity of 154.2 mgEE₂ Kgₛₒᵢₗ⁻¹, showing affinity with EE2.