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Water treatment residues as accumulators of oxoanions in soil: sorption of arsenate and phosphate anions from an aqueous solution

Castaldi, Paola and Mele, Elena and Silvetti, Margherita and Garau, Giovanni and Deiana, Salvatore Andrea (2014) Water treatment residues as accumulators of oxoanions in soil: sorption of arsenate and phosphate anions from an aqueous solution. Journal of Hazardous Materials, Vol. 264 , p. 144-152. ISSN 0304-3894. eISSN 1873-3336. Article.

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DOI: 10.1016/j.jhazmat.2013.10.037

Abstract

Here we report a survey addressed to determine, at different pH values (pH 4.0, 7.0 and 9.0), the ability of two different water treatment residues, a Fe-based (Fe-WTR) and an Al-based (Al-WTR), to accumulate arsenate and phosphate anions from an aqueous solution and to define the mechanism which regulate the sorption of these anions. Fe-WTR showed a greater As(V) and P(V) sorption capacity respect to Al-WTR at all the pH values investigated, in particular at pH 4.0. The greater capacity of the Fe-WTR to accumulate phosphate at pH 4.0 seems to be linked to the higher content of manganese ions compared to Al-WTR, which can give rise, with phosphate ions, to the formation of MnHPO4 precipitates. Sequential extraction of As(V)- or P(V)-WTRs suggested that the main mechanism governing the sorption of both two anions likely involve the formation of inner-sphere surface complexes [Fe/Al–O–As(P)]. Such a coordination mode was supported by the FT-IR spectra that exhibit well resolved band at 865 cm−1 and 1040 cm−1 attributable to ν(As–O) or ν(P–O) stretching vibration, respectively.

Item Type:Article
ID Code:9748
Status:Published
Refereed:Yes
Uncontrolled Keywords:Fe- and Al-WTRs, arsenate and phosphate, adsorption isotherms, sequential extraction, FT-IR spectroscopy
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/13 Chimica agraria
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Agraria
Publisher:Elsevier
ISSN:0304-3894
eISSN:1873-3336
Copyright Holders:© 2013 Elsevier
Deposited On:09 Apr 2014 09:17

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