Sorption of uranium(VI) onto hydrous ferric oxide-modified zeolite: Assessment of the effect of pH, contact time, temperature, selected cations and anions on sorbent interactions

Sorption of uranium(VI) onto hydrous ferric oxide-modified zeolite: Assessment of the effect of... Zeolites are commonly used as adsorbents for metal removal in most applications e.g. in wastewater. However, the ubiquity of iron in such systems may, in the long-term, distort the true interactions and mechanisms of contaminant removal as a result of modification of the zeolite surface. In this study, this potential phenomenon was assessed for the removal of uranium(VI) from aqueous solution by hydrous ferric oxide-modified zeolite (HFOMZ). This was prepared by precipitating iron hydroxide (the common precipitate of iron in aqueous systems) onto zeolite. The prepared HFOMZ was characterised by the scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Batch adsorption experiments were performed to assess the effect of: pH, initial uranium(VI) concentration, adsorbent dosage, contact time, temperature, presence of cations (Pb2+, Cr3+, Cu2+, Mn2+ and Co2+) and anions (SO42−, CO32− and HPO42−) on the adsorption of uranium(VI). Kinetic studies under these conditions indicated that the pseudo second-order kinetic model (R2 > 0.99) best described the adsorption behaviour, implying that this could be proceeding through a chemisorption process. The experimental data was best described by the Freundlich isotherm model (R2 > 0.93), an implication that the adsorption surface was heterogeneous. The thermodynamic parameters calculated from the experimental data suggested that the adsorption of U(VI) onto HFOMZ was spontaneous and exothermic in nature. The adsorption of U(VI) onto HFOMZ was dominated by complexation with strong ionizable hydroxyl sites on the hydrous ferric oxide surfaces and the edge sites of the zeolite. At pH values from 2 to 6, increased adsorption was observed and this decreased at higher pH values (above 6). This corresponded with the changes in speciation as determined by the PHREEQC modelling code. The presence of the cations (Pb2+, Cr3+, Cu2+, Mn2+ and Co2+) and anions (CO32− and HPO42−) resulted in a significant decrease in the adsorption capacity of U(VI) by HFOMZ, implying that in a system where these anions and cations are present in high concentrations over time, U(VI) will adsorb less onto the material. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Environmental Management Elsevier

Sorption of uranium(VI) onto hydrous ferric oxide-modified zeolite: Assessment of the effect of pH, contact time, temperature, selected cations and anions on sorbent interactions

Loading next page...
 
/lp/elsevier/sorption-of-uranium-vi-onto-hydrous-ferric-oxide-modified-zeolite-x1xn0NX9pX
Publisher
Elsevier
Copyright
Copyright © 2017 Elsevier Ltd
ISSN
0301-4797
D.O.I.
10.1016/j.jenvman.2017.09.034
Publisher site
See Article on Publisher Site

Abstract

Zeolites are commonly used as adsorbents for metal removal in most applications e.g. in wastewater. However, the ubiquity of iron in such systems may, in the long-term, distort the true interactions and mechanisms of contaminant removal as a result of modification of the zeolite surface. In this study, this potential phenomenon was assessed for the removal of uranium(VI) from aqueous solution by hydrous ferric oxide-modified zeolite (HFOMZ). This was prepared by precipitating iron hydroxide (the common precipitate of iron in aqueous systems) onto zeolite. The prepared HFOMZ was characterised by the scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Batch adsorption experiments were performed to assess the effect of: pH, initial uranium(VI) concentration, adsorbent dosage, contact time, temperature, presence of cations (Pb2+, Cr3+, Cu2+, Mn2+ and Co2+) and anions (SO42−, CO32− and HPO42−) on the adsorption of uranium(VI). Kinetic studies under these conditions indicated that the pseudo second-order kinetic model (R2 > 0.99) best described the adsorption behaviour, implying that this could be proceeding through a chemisorption process. The experimental data was best described by the Freundlich isotherm model (R2 > 0.93), an implication that the adsorption surface was heterogeneous. The thermodynamic parameters calculated from the experimental data suggested that the adsorption of U(VI) onto HFOMZ was spontaneous and exothermic in nature. The adsorption of U(VI) onto HFOMZ was dominated by complexation with strong ionizable hydroxyl sites on the hydrous ferric oxide surfaces and the edge sites of the zeolite. At pH values from 2 to 6, increased adsorption was observed and this decreased at higher pH values (above 6). This corresponded with the changes in speciation as determined by the PHREEQC modelling code. The presence of the cations (Pb2+, Cr3+, Cu2+, Mn2+ and Co2+) and anions (CO32− and HPO42−) resulted in a significant decrease in the adsorption capacity of U(VI) by HFOMZ, implying that in a system where these anions and cations are present in high concentrations over time, U(VI) will adsorb less onto the material.

Journal

Journal of Environmental ManagementElsevier

Published: Dec 15, 2017

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off