Evaluation of the effectiveness of microparticle-embedded cryogel system in removal of 17β-estradiol from aqueous solution

Abstract

A B S T R A C TIn this study, we have synthesized microparticle-embedded cryogel system for removal of 17β-estradiol (E2). Firstly, the poly(hydroxyethyl methacrylate-N-methacryloyl-L-tryptophan methyl ester) poly(HEMA-MATrp) microparticles were produced by emulsion polymerization. And then, poly(HEMA-MATrp) microparticles were embedded in poly(hydroxyethyl methacrylate) cryogel and [PHEMA/MATrp] cryogel system was prepared. [PHEMA/ MATrp] cryogel system was used for the removal of E2. The characterization studies of the poly(HEMA-MATrp) microparticles and cryogel system were conducted by infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and swelling studies. The effects of initial concentration, temperature, and contact time on adsorption of E2 were investigated. Maximum adsorption capacity of PHEMA/MATrp cryogel was determined as 2.75 mg E2/g cryogel at 25˚C. The adsorption process obeyed both pseudo-second-order and intraparticle diffusion kinetic models. All the isotherm data can be fitted Langmuir isotherm model with high correlation coefficients for all studied temperatures. Thermodynamic parameters ΔH˚= 654.9 J/mol, ΔS˚= 85.90 J/K/mol, and ΔG˚= −23.14 to −26.23 kJ/mol with the rise in temperature from 4 to 40˚C indicated that the adsorption process was endothermic and spontaneous. The E2 adsorption capacity did not change after five batch successive adsorption-desorption cycles, demonstrating the usefulness of the microparticle-embedded cryogel system in applications.