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Evaluation of thiol-modified vermiculite for removal of Hg(II) from aqueous solutions
https://orcid.org/0000-0002-0496-9009
Abstract Aiming the removal of Hg(II) from waters, Na+ exchanged vermiculite (Na-VT) was modified with l-cysteine (CYS-VT), cysteamine hydrochloride (CTA-VT) and (3-mercaptopropyl) trimethoxysilane (3-MPS-VT). Modification with CTA and CYS was made at pH6.0±0.1 to facilitate ion exchange of Na+ in the interlayer with the protonated amines. Modification with 3-MPS was made by silylation, covalently binding the modifier to the silanols. Initial adsorption rate (μmolg−1 min−1) on Na-VT and 3-MPS-VT was very fast and obeyed a pseudo second order kinetics. Intraparticle diffusion controlled the initial adsorption rate in CTA-VT and CYS-VT. Adsorption isotherms constructed at pH6.0±0.1 and 25.0±0.5°C fitted to Langmuir and Freundlich equations. The adsorption capacities of CTA-VT, CYS-VT, 3-MPS-VT and Na-VT were 83±30, 57±4, 21±2 and 18±1μmolg−1 (n =3), respectively. The adsorption capacity in columns followed the order: 3-MPS-VT>CTA-VT>CYS-VT>Na-VT, which is consistent with the instantaneous adsorption on 3-MPS-VT and the intraparticle diffusion control in CTA-VT and CYS-VT. The modifications afforded materials with adsorption capacities less affected by variation of ionic strength and pH as a consequence of the strong binding of Hg(II) to the incorporated thiols.
Graphical abstract Display Omitted
Highlights Vermiculite was modified with thiols for use as adsorbent for Hg(II). l-cysteine and cysteamine at the interlayer space increased the adsorption capacity. (3-Mercaptopropyl)trimethoxysilane modification was suitable for adsorption in columns. Adsorption on modified materials was predominantly irreversible. The modified materials have potential for in-situ remediation.
Evaluation of thiol-modified vermiculite for removal of Hg(II) from aqueous solutions
https://orcid.org/0000-0002-0496-9009
Abstract Aiming the removal of Hg(II) from waters, Na+ exchanged vermiculite (Na-VT) was modified with l-cysteine (CYS-VT), cysteamine hydrochloride (CTA-VT) and (3-mercaptopropyl) trimethoxysilane (3-MPS-VT). Modification with CTA and CYS was made at pH6.0±0.1 to facilitate ion exchange of Na+ in the interlayer with the protonated amines. Modification with 3-MPS was made by silylation, covalently binding the modifier to the silanols. Initial adsorption rate (μmolg−1 min−1) on Na-VT and 3-MPS-VT was very fast and obeyed a pseudo second order kinetics. Intraparticle diffusion controlled the initial adsorption rate in CTA-VT and CYS-VT. Adsorption isotherms constructed at pH6.0±0.1 and 25.0±0.5°C fitted to Langmuir and Freundlich equations. The adsorption capacities of CTA-VT, CYS-VT, 3-MPS-VT and Na-VT were 83±30, 57±4, 21±2 and 18±1μmolg−1 (n =3), respectively. The adsorption capacity in columns followed the order: 3-MPS-VT>CTA-VT>CYS-VT>Na-VT, which is consistent with the instantaneous adsorption on 3-MPS-VT and the intraparticle diffusion control in CTA-VT and CYS-VT. The modifications afforded materials with adsorption capacities less affected by variation of ionic strength and pH as a consequence of the strong binding of Hg(II) to the incorporated thiols.
Graphical abstract Display Omitted
Highlights Vermiculite was modified with thiols for use as adsorbent for Hg(II). l-cysteine and cysteamine at the interlayer space increased the adsorption capacity. (3-Mercaptopropyl)trimethoxysilane modification was suitable for adsorption in columns. Adsorption on modified materials was predominantly irreversible. The modified materials have potential for in-situ remediation.
Evaluation of thiol-modified vermiculite for removal of Hg(II) from aqueous solutions
https://orcid.org/0000-0002-0496-9009
Abstract Aiming the removal of Hg(II) from waters, Na+ exchanged vermiculite (Na-VT) was modified with l-cysteine (CYS-VT), cysteamine hydrochloride (CTA-VT) and (3-mercaptopropyl) trimethoxysilane (3-MPS-VT). Modification with CTA and CYS was made at pH6.0±0.1 to facilitate ion exchange of Na+ in the interlayer with the protonated amines. Modification with 3-MPS was made by silylation, covalently binding the modifier to the silanols. Initial adsorption rate (μmolg−1 min−1) on Na-VT and 3-MPS-VT was very fast and obeyed a pseudo second order kinetics. Intraparticle diffusion controlled the initial adsorption rate in CTA-VT and CYS-VT. Adsorption isotherms constructed at pH6.0±0.1 and 25.0±0.5°C fitted to Langmuir and Freundlich equations. The adsorption capacities of CTA-VT, CYS-VT, 3-MPS-VT and Na-VT were 83±30, 57±4, 21±2 and 18±1μmolg−1 (n =3), respectively. The adsorption capacity in columns followed the order: 3-MPS-VT>CTA-VT>CYS-VT>Na-VT, which is consistent with the instantaneous adsorption on 3-MPS-VT and the intraparticle diffusion control in CTA-VT and CYS-VT. The modifications afforded materials with adsorption capacities less affected by variation of ionic strength and pH as a consequence of the strong binding of Hg(II) to the incorporated thiols.
Graphical abstract Display Omitted
Highlights Vermiculite was modified with thiols for use as adsorbent for Hg(II). l-cysteine and cysteamine at the interlayer space increased the adsorption capacity. (3-Mercaptopropyl)trimethoxysilane modification was suitable for adsorption in columns. Adsorption on modified materials was predominantly irreversible. The modified materials have potential for in-situ remediation.
Evaluation of thiol-modified vermiculite for removal of Hg(II) from aqueous solutions
do Nascimento, Fernando Henrique (author) / de Souza Costa, Diego Miranda (author) / Masini, Jorge Cesar (author)
Applied Clay Science ; 124-125 ; 227-235
2016-02-13
9 pages
Article (Journal)
Electronic Resource
English
Mercury , Adsorption , Cysteine , Cysteamine , Vermiculite , 3-MPS , Chronopotentiometry
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