Hydroxypropyl Methylcellulose Sponges for the Adsorption of Estrogenic Pollutant

Hydroxypropyl methylcellulose (HPMC) E4M chains are crosslinked with citric acid and ethylenediaminetetraacetic acid (EDTA), resulting in adsorbent sponges (SpE4M), which are impregnated with magnetic nanoparticles (SpE4M-mag) for the adsorption of 17 α-ethinyl estradiol (EE). The characterization of SpE4M and SpE4M-mag characterization includes X-ray microcomputer tomography (Micro-CT), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) vibrational spectroscopy, elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray diffraction (XRD). SpE4M and SpE4M-mag present porosities of 72±6 % and 80±7 %, respectively, and outstanding stability in water, in the pH range 4 to 8, and in alcohols, alkanes, and acetone. The compressive moduli of SpE4M and SpE4M-mag amount to 2.75 and 4.37 MPa, respectively. The adsorption of 17 α-ethinyl estradiol (EE), an estrogenic pollutant, on SpE4M and SpE4M-mag follows the pseudo-first-order kinetic model. The EE removal capacity by SpE4M is 78±5 %, which is twice that presented by SpE4M-mag. The new sponges are recovered successfully either by flotation or by an external magnet, and can be recycled five times keeping 80 % of their initial removal capacity after the fifth cycle, disclosing their potential for environmental remediation.