Sepiolite and sepiolite-bound humic acid interactions in alkaline media and the mechanism of the formation of sepiolite-humic acid complexes

Sabah, E and Ouki, Sabeha (2017) Sepiolite and sepiolite-bound humic acid interactions in alkaline media and the mechanism of the formation of sepiolite-humic acid complexes International Journal of Mineral Processing, 162. pp. 69-80.

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Abstract

The surface-controlled reactions and interfaces of clays and/or clay minerals are strongly determined by the adsorption of dissolved humic substances which have surface active characters. Consequently, this may lead to an improved understanding of organo-clay complexes for remediation purposes of polluted areas. The interactions between sepiolite and sepiolite-bound humic acid (HA), and its influence on the mechanism of the formation of sepiolite-humic acid complexes were examined by characterizing the structure of sepiolite through UV/Vis spectroscopy, field emission scanning electron microscopy (SEM+FEG), specific surface area, pore size and volume, and Fourier transform infrared spectroscopy (FTIR). The UV-VIS spectral results of the raw sepiolite showed that there is no correlation between UV254 and the amount of humic substance released from sepiolite is dependent on increasing extraction time. The low values of humification index of the sepiolite confirmed the presence of HA with higher, and similar molecular weight, particle size, humification degree and aromaticy. Hence, it can be concluded that HA groups are presumably associated with the large quantity of silanol groups located on the sepiolite external surface preferentially through H-bonds and/or surface complexation interactions between the functional groups in HA and dissolved metal cations (Mn+). This finding is in good agreement with results from FTIR and SEM-FEG investigations. EDAX analysis of the HA-extracted sepiolite illustrated a strong decrease in Mg2+, Ca2+ and K+ content indicating that electrically charged sites on HA may form metal complexes of high stability through chelation.

Item Type:	Article
Subjects :	Civil & Environmental Engineering
Divisions :	Faculty of Engineering and Physical Sciences > Civil and Environmental Engineering
Authors :	Name Email ORCID Sabah, E UNSPECIFIED UNSPECIFIED Ouki, Sabeha S.Ouki@surrey.ac.uk UNSPECIFIED
Date :	31 March 2017
Identification Number :	https://doi.org/10.1016/j.minpro.2017.03.005
Copyright Disclaimer :	© 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords :	Sepiolite; sepiolite-bound humic; humic acid complexes; extraction; mechanism
Depositing User :	Symplectic Elements
Date Deposited :	05 Apr 2017 13:41
Last Modified :	04 Jul 2017 15:25
URI:	http://epubs.surrey.ac.uk/id/eprint/813958

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