Municipal solid waste compost as a novel sorbent for antimony(V):
adsorption and release trials at acidic pH
Gian Paolo Lauro
Received: 6 September 2017 /Accepted: 3 December 2017 /Published online: 8 December 2017
Springer-Verlag GmbH Germany, part of Springer Nature 2017
The ability of two municipal solid waste composts (MSW-Cs) to sorb antimony(V) in acidic conditions (pH 4.5) was investi-
gated. Sorption isotherms and kinetics showed that both MSW-Cs could sorb antimony(V), even if in different amounts (~ 0.18
and 0.24 mmol g
of Sb(V) by MSW-C1 and MSW-C2, respectively). These differences were ascribed to the chemical
composition of composts, as well as to the total acidity of their humic substances. The Sb(V) sorption by both MSW-Cs followed
a pseudo-second-order kinetic model, while the sorption isotherms data fitted the Freundlich model better than the Langmuir one.
The humic acids extracted from composts contributed to 4.26 and 8.24% of Sb(V) sorption by MSW-C1 and MSW-C2 respec-
tively. SEM-EDX spectra of the MSW-C+Sb(V) systems showed a certain association of Ca(II) with Sb(V), while sequential
extraction procedures indicated that more than 80% of the Sb(V) sorbed was strongly retained by MSW-Cs. On the other hand,
treatment with oxalic acid at pH 4.5 favored the release of more than 98 and 65% of the Sb(V) sorbed by MSW-C1 and MSW-C2
respectively, supporting a possible role of calcium in Sb(V) retention. The results from this study suggest that MSW-Cs could be
used as amendments for the in-situ immobilization of Sb(V) in acidic-polluted soils.
Municipal solid waste compost
Antimony (Sb) and its compounds are considered as priority
pollutants by the international environmental protection agen-
cies (CEC 1998;USEPA2009), because of their high toxicity
and no known biological role (Filella et al. 2002a, 2002b;
Tella and Pokrovsky 2009; Dousova et al. 2015). The
Environmental Protection Agency of the United States
(USEPA) established 6 μgl
as the maximum contaminant
level (MCL) for Sb in drinking water (USEPA 2009), while
the European Union fixed a maximum admissible concentra-
tion of 5 μgl
(CEC 1998). On the other hand, mean
background Sb levels in soils range from 0.25 to 1.04 mg kg
(Kabata-Pendias 2010). However, the metalloid can be found
in much higher concentrations where Sb-rich ores are present
in the pedogenic material and/or as a consequence of anthro-
pogenic activities (Tella and Pokrovsky 2009; Wilson et al.
2010; Martínez-Lladó et al. 2011; Tella and Pokrovsky 2012).
In particular, antimony can mainly occur as stibnite (Sb
the primary Sb ore, and valentinite (Sb
), which is an oxi-
dation product of stibnite (Filella et al. 2002b;Kabata-Pendias
2010; Wilson et al. 2010). Anthropogenic sources of antimony
include mining activity and industrial emissions; however,
plastic waste, road traffic, and shooting ranges have become
the dominant Sb sources in the last decades (Dousova et al.
2015; Ceriotti and Amarasiriwardena 2009). As a result,
heavily Sb-polluted sites have been recently found in Europe
(e.g., in Italy, Germany, and Switzerland with up to ~ 100, ~
500 and ~ 17,000 mg kg
) (Tschan et al. 2009; Garau et al.
2017) as well as worldwide (e.g., in Iran, Canada, and China
with up to ~ 640, ~ 1000 and ~ 7300 mg kg
) (Rafiei et al.
2010;Wangetal.2010; Fawcett et al. 2015).
Antimony, according to thermodynamic equilibrium esti-
mates, can occur in most natural systems in two oxidation
Responsible editor: Guilherme L. Dotto
* Giovanni Garau
* Paola Castaldi
Dipartimento di Agraria, Sezione di Scienze e Tecnologie Ambientali
e Alimentari, University of Sassari, Viale Italia 39,
07100 Sassari, Italy
Environmental Science and Pollution Research (2018) 25:5603–5615