Synthesis and characterisation of activated carbon from agroindustrial waste—Preliminary study of 17β-estradiol removal from aqueous solution

• Agroindustrial wastes as adsorbents for removal 17β-estradiol in aqueous solution.
• Activated carbon from coffee waste and wood sawdust (100%) had a better E2 removal than from apple waste (81.6%).
• Leaching inorganic compounds with HCl, greater amount of pores (CS = 0.0368 cm3 g−1 to ACCSA7 = 0.2822 cm3 g−1).
• Hydrogen bonds interaction between adsorbent and E2 molecules.
• Instantaneous dipole-induced dipole interaction between adsorbent and E2 molecules.

In this study, new activated carbons from coffee, wood and apple pomace wastes were synthesised by pyrolysis and subsequent acid wash under reflux. These materials were characterised by a combination of spectroscopic and chemical techniques including SEM, BET, TGA, WCA, FT-IR, and pHPZC. The carbons prepared were applied as adsorbents in the removal of 17β-estradiol (E2) from aqueous solutions. In general, the results of characterisation of the manufactured adsorbents showed that the surfaces properties size and pore distribution are dependent on the precursor used. Furthermore, the leaching of inorganic compounds with HCl causes structural modification, which leaves the materials more active in interactions with 17β-estradiol. The highest percentage of E2 removal was obtained for samples from coffee and wood wastes, where the percentage of E2 removal was 100%, with exception of CS sample. For activated carbon from apple pomace, the activation process increased its adsorption capacity about two-fold (39.2–81.6%) (E2 = 0.500 mg L−1). In addition, amount of E2 adsorbed were: CS, ACCSA7, ACCSA10 and ACM = 0.33 mg g−1; AP = 0.13 mg g−1; ACAP7 = 0.27 mg g−1 (E2 = 0.500 mg L−1) and ACCSA7, ACCSA10 and ACM = 5.07 mg g−1; CS = 4.95 mg g−1; AP = 2.05 mg g−1 and ACAP7 = 2.35 mg g−1 (E2 = 7.60 mg L−1). These aspects demonstrate the potential of activated carbon from agroindustrial wastes as new adsorbents for the removal of 17β-estradiol in aqueous solution.

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