Environmental Engineering Reference
In-Depth Information
7.
C
HARACTERIZATION OF
W
ATER
AND
A
CIDS
S
OLUBLE
C
D
Fractions of Cd: soluble in water and soluble in acids adequately equals to
(mg · kg
-1
): 1.4 (Psenner), 3.5 (Tessier), 1.9 (BCR), 4.0 (Sposito), 3.2 (Kersten
i Förstner), 4.1 (Rudd) i 3.1 (Gatehouse) - Table 1. Considering total amount
of Cd extracted from coal fly ash to solution (mobile Cd) in form of
exchangeable fraction in ratio of total content of Cd in coal fly ash
(19.0 mg · kg
-1
), the results attributed to studied methods can be put in order:
Psenner (7.4%) < BCR (10.0%) < Gatehouse (16.3%) < Kersten i Förstner
(16.8%) < Tessier (18.4%) < Sposito (21.0%) < Rudd (21.6%).
This indicated that maximum amounts of mobile Cd as exchangeable
fraction and soluble in acids fraction are obtained by the use of Rudd and
Gatehouse method.
8.
A
PPARATUS
The heating digester with programmable increase of temperature from 25
to 450°C Model DK6 with mineralizations groups finalized to heavy metals
trace determinations Model TMD6 of the VELP Company (Italy)™ was used.
A centrifuge tube test Model WE-6 (Precision Engineering, Poland) ® was
used for the centrifugation of the coal fly ash extracts at the speed 2500 rpm.
The pH measurements were conducted using pHmeter (Elmetron, CPI-551
model)®. A universal shaker Model 358 A of the ELPIN-PLUS
company
(Poland)™ and electric hotplate with temperature control and digital display to
1°C Model SD 300 of the STUART company (England)™ were used for the
extraction. The coal fly ash samples were dried with electric drier model KBC-
65G of the WAMED Company (Poland)®. The deionizator of the Cobrabid-
AQUA Company (Poland)™ was used for the deionization of water.
Measurements were carried out by means of atomic absorption
spectrometer model 3100 (PERKIN-ELMER)™ (λ = 228.8 nm for Cd [31]).
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