Adsorption Of 17?-estradiol And 17?-ethynylestradiolby Montmorillonite/Hydrochar Nanocomposites In Aqueous Environment

With a view to reducing estrogens pollution in aqueous environment,montmorillonite(MMT)and husk biomass were compounded by hydrothermal carbonization method(HTC)to obtain montmorillonite/hydrochar(MMT/HC).MMT/HC with or without modification by KOH was applied to remove 17?-estradiol(E2)and 17?-ethynylestradiol(EE2).The modified montmorillonite/hydrochar composites with different KOH concentrations(KOH:MMT/HC=1%,4%and 8%)were modified to obtain modified montmorillonite/hydrochar composites(they were named as MMT/HC-K1,MMT/HC-K4 and MMT/HC-K8,repectivley).In this study,the surface and internal characteristics of the original and modified materials were compared by specific surface area and pore size analysis(BET),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and thermogravimetry(TGA),X ray diffraction(XRD).It was observed that the specific surface area of MMT/HC was about5 times larger than that of the original material,but its thermal stability was lower than that of MMT/HC,and the surface morphology of MMT/HC was obviously changed by SEM and TEM analysis,but the layered structure of MMT was retained.The results of element analysis that carbon content of MMT/HC was higher than that of MMT and lower than that of HC verified that MMT was successfully combined with HC.In addition,it was also found that HC and MMT might be bound by the newly formed carbonyl bond(C-O-H)by FTIR analysis.MMT/HC with 1%KOH(MMT/HC-K1)exhibited excellent adsorption ability(E2:Q_m=138 mg/g,EE2:Q_m=69 mg/g)than those of other adsorbents,and it approximately 2-fold higher than that of HC.Moreover,the adsorption capacity maintained high level over a wide pH range(3.0-8.0).The pseudo-second-order model and Freundlich model exhibited prior fitting performance for adsorption of E2 and EE2.The regenerated MMT/HC-K1 retained over 80%of its initial capacity after four cycles.The adsorption mechanism on MMT/HC-K1 could be explained by hydrophobicity,?-?bond,electrostatic interaction and H-bonding interaction.In a word,MMT/HC-K1,synthesis from two low-cost materials,could be considered as a competitive adsorbent for estrogens removal from aqueous environment,regarding its high adsorption capacity and regeneration ability.