Hydrothermal synthesis of montmorillonite/hydrochar nanocomposites and application for 17β-estradiol and 17α-ethynylestradiol removal

Abstract

abWith a view to reducing estrogens pollution in aqueous environments, montmorillonite/hydrochar (MMT/ HC) with or without modification by KOH via hydrothermal carbonization process (HTC) were applied to remove 17b-estradiol (E2) and 17a-ethynylestradiol (EE2). The characterizations of MMT/HC indicated that MMT had been successfully attached onto HC surface, which could cause an improvement in the stability of the clay nanoparticles. MMT/HC with 1% KOH (MMT/HC-K1) exhibited excellent adsorption) compared to those of other adsorbents; approximately 2-fold higher than that of HC. Moreover, the adsorption capacity maintained a high level over a wide pH range (2-8). 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, p-p bond, electrostatic interaction and H-bonding interaction. Overall, MMT/HC-K1 synthesis from two low-cost materials, could be considered as a competitive adsorbent for estrogens removal from aqueous environment, considering its high adsorption capacity and regeneration ability.

Sequestration of steroidal estrogen in aqueous samples using an adsorption mechanism: a systemic scientometric review

“…The improved electron density of the benzene ring enables it to function as a powerful e − giver; at highly acidic pH (pH ≤ 2), the hydroxyl and ketonic functional groups are protonated, and the SE is in their cationic form. 92 The findings above corroborate the findings of other researchers who have equally accentuated that interactions occur between the phenolic moiety of SE and the e − acceptor groups tied to adsorbent, 95,104,105 and this results in efficacious adsorption.…”

Recent Advances on Innovative Materials from Biowaste Recycling for the Removal of Environmental Estrogens from Water and Soil

“…The Freundlich model was the best interpretation of equilibrium sorption data of various EEs on BC [ 52 , 53 , 101 ], HC [ 52 , 58 ] and DG [ 12 ]. Differently, other works demonstrated that the Langmuir model was the most appropriate fit for EEs on BC [ 43 , 46 , 90 ] and HC [ 57 , 102 ].…”

“…In order to enhance the adsorbing performance of HC, researchers have carried out several specific activation treatments during or after the HTC process [ 54 , 55 ]. Common activating agents adopted for HC are alkali metal hydroxides such as NaOH [ 56 ] and KOH [ 57 ] and single or binary salts [ 58 ].…”

“…The IPD model is applied to know the limiting step of adsorption and assumes that the only interaction between solute and adsorbent is the internal diffusion [ 108 ]. Numerous studies demonstrated that the PSO kinetic model is the best fit for the adsorption of most EEs on BC [ 43 , 46 , 90 ] and HC [ 56 , 57 , 58 ].…”

“…In a recent work, de Lima et al [ 56 ] found a very high sorption capacity of BPA on a NaOH-activated HC. Likewise, a KOH-activated HC was very efficient in the removal of E2 and EE2 [ 57 ].…”