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

作者：Castaldi Paola^*; Mele Elena; Silvetti Margherita; Garau Giovanni; Deiana Salvatore

来源：Journal of Hazardous Materials, 2014, 264: 144-152.

DOI：10.1016/j.jhazmat.2013.10.037

• Fe- and Al-WTRs
• Arsenate and phosphate
• Adsorption isotherms
• Sequential extraction
• FT-IR spectroscopy

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)-VVTRs 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)1. 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 nu(As-0) or nu(P-O) stretching vibration, respectively.

• 出版日期2014-1-15