Evaluation of iron-coated ZSM-5 zeolite for removal of
As(III) from aqueous solutions in batch and column systems
Saeid Ezati, Bubak Souri and Afshin Maleki
ABSTRACT
Influential parameters to produce iron-coated ZSM-5 zeolite including iron loading concentration,
calcination temperature and time, synthesis temperature and mixing intensity were investigated.
Results showed that the optimized iron-coated ZSM-5 nano-adsorbent is produced if 40 wt.% iron
loading concentration at 30
W
C synthesis temperature under 60 rpm mixing intensity and 400
W
C
calcination temperature for 3 h are applied. Also, optimization of some parameters such as pH,
adsorbent dose, contact time and temperature for removal of arsenite from aqueous solution with
400 μg/L initial concentration was considered. Evidently, the highest adsorption of arsenite occurred
under pH 7, adsorbent dose 2.5 g/L, contact time 30 min and temperature 40
W
C. Kinetic and
isotherm models studied showed that arsenite adsorption by iron-coated ZSM-5 follows a pseudo-
third-order equation and well fitted with the Langmuir isotherm model. Evaluation showed that the
optimized iron-coated ZSM-5 zeolite is able to remove up to 98.37% of arsenite under the best
conditions in a batch reactor. For the column system, arsenite concentration range of 0.04–97.53 μg/L
in output at 1–35 min interval was confirmed and the breakthrough curve showed that iron-coated
ZSM-5 nano-adsorbent was saturated after 215 min whereas Fe, pH and EC measured in output
solution were 0.90 mg/L, 6.65 and 148.40 μs/cm, respectively.
Saeid Ezati
Bubak Souri (corresponding author)
Department of Environmental Sciences, Faculty of
Natural Resources,
University of Kurdistan,
P.O. Box 416,
Sanandaj,
Iran
E-mail: bsouri@uok.ac.ir
Afshin Maleki
Environmental Health Research Center,
Kurdistan University of Medical Sciences,
Sanandaj,
Iran
Key words | As(III), aqueous solution, batch, column, iron-coated ZSM-5
INTRODUCTION
Arsenic (As) is a carcinogenic trace metal that is toxic to
human and animals. It occurs naturally in soils and can be
mobilized through weathering reactions and biological
activities which may lead to contamination of aquifers
(Mohan & Pittman ). Additionally, anthropogenic dis-
charge and disposal of As-containing compounds may lead
to even greater concentrations of it (Mandal & Suzuki
). In nature this element mainly exists as two forms of
oxy-anion including arsenite As(III) and arsenate As(V)
(Greenwood & Earnshaw ). Because of severe toxicity
of As to humans its permissible concentration limit in drink-
ing water is defined as 10 μg/l (Haque et al. ). Among
the several methods that exist for removal of As, adsorption
is one of the most commonly used methods (Mohan & Pitt-
man ). Previous studies have demonstrated that As tends
to accumulate on the surface of metal oxides such as Fe, Mn,
Al, Cu, and Co residing on zeolites, pumice and clay min-
erals as support (Mandal & Suzuki ; Babaie Far et al.
). Iron oxide based materials are found effective for
removal of heavy metal ions including As (arsenate and
arsenite) from solutions (Sarkar et al. ). Support
materials have always been considered as key factors influen-
cing nano-adsorbent activities. Numerous micro/
mesoporous materials such as zeolite (ZSM-5, clinoptilolite
(Davila-Jimenez et al. ) have been applied for removal
of As from aqueous solutions. Zeolite minerals such as
10 © IWA Publishing 2017 Water Science & Technology: Water Supply | 17.1 | 2017
doi: 10.2166/ws.2016.104
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