Article ID Journal Published Year Pages File Type
150191 Chemical Engineering Journal 2012 8 Pages PDF
Abstract

New criteria in assessing the quality of drinking water reduced the maximum permissible concentration of arsenic from 50 μg L−1 to 10 μg L−1, and set a requirement for the development of new technologies for arsenic removal. In this paper, ethylenediamine functionalized multiwall carbon nanotubes (e-MWCNT) were loaded with iron(III) oxide in the goethite form, by precipitation of adsorbed Fe3+ and oxidized Fe2+ using base, in that way e-MWCNT/Fe3+ and e-MWCNT/Fe2+ adsorbents, respectively, were obtained. The influence of pH on the As(V) and As(III) removal from drinking water was studied in a batch system, of pH range 3–10 and initial arsenic concentration 0.05–4 mg L−1. Time dependent As(V) adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Freundlich isotherm, applying linear and non-linear fitting methods. The maximum adsorption capacities obtained from Langmuir model for As(V) on e-MWCNT/Fe2+ and e-MWCNT/Fe3+ were 23.47 and 13.74 mg g−1 at 25 °C, respectively. Thermodynamic parameters showed that the adsorption of As(V) was spontaneous and endothermic for both e-MWCNT/Fe2+ and e-MWCNT/Fe3+. Influences of the pH, iron(III) oxide loading and interfering ions were modeled by MINTEQ program, and good agreement between experimental and modeling data was obtained.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Iron(III)-oxide loaded e-MWCNT shows good sorption affinity for arsenic(V). ► The sorption pattern of As(V) fits well to the Freundlich model. ► As(V) adsorption is dependent to iron(III)-oxide content, pH and temperature. ► The sorption of As(V) and As(III) is a rather complex and spontaneous process. ► Creation of inner-sphere surface complexes are main sorption mechanisms.

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Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
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