Removal of the synthetic hormone methyltestosterone from aqueous solution using a β-cyclodextrin/silica composite. Issue 6 (December 2019)

• Record Type: Journal Article
• Authors: Carvalho, Lucas Bragança; Chagas, Pricila Maria Batista; Marques, Tamara Rezende; Razafitianamaharavo, Angelina; Pelletier, Manuel; Nolis, Pau; Jaime, Carlos; Thomasi, Sérgio Scherrer; Pinto, Luciana de Matos Alves
• Is Part Of: Journal of environmental chemical engineering. Volume 7:Issue 6(2019)
• Publication Date: 2019-12
• Subjects: Methyltestosterone -- β-Cyclodextrin -- Composite -- Adsorption -- Steroid contaminants; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2019.103492
• Languages: English
• ISSNs: 2213-2929

Abstract

Graphical abstract: Highlights: β-cyclodextrin were functionalized on silica by esterification reaction. β-cyclodextrin and silica composite was used for the adsorption of methyltestosterone. Steroid removal occurs by the formation of inclusion compounds with cyclodextrin. The composite has high capacity for removal in a short period of time. Ethanol is effective in regenerating the material and making it suitable for reuse. Abstract: Contamination of water with steroid residues can cause a number of environmental damages, affecting exposed organisms including man. The development of technologies for treatment or removal of this type of micropollutant from water is of paramount importance. In this study, citric acid was used to functionalize β-Cyclodextrin (bCD) on the silica surface generating an organic-inorganic hybrid composite for application in molecular sequestration. The functionalization percentage was high, with about 62.6% of the composite mass corresponding to the organic part of the material. 13 C NMR and infrared spectroscopic analysis indicate that the functionalization mechanism occurs by an esterification reaction between the citric acid with the silanol groups from silica and the primary hydroxyls of the bCDs. Fast adsorption of the methyltestosterone steroid was observed at acid pH, with a high adsorption capacity of 11 mg g −1 . The best kinetic and isotherm models fit indicated that the adsorption occurred by a physical mechanism at independent sites with the steroid molecule possibly captured by two bCDs. The removal process was spontaneous and exothermic, with the existence of weak interactions between the hormone and the composite, and its regeneration is quite fast efficient with the displacement of the complexation equilibrium. The results obtained in this study demonstrate the considerable potential of the composite for use in the treatment of wastewater containing the steroid studied, and its efficacy should be evaluated for other steroid molecules.