2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
Table I
Calculated values from calibration plots
T h e S t o i c h i o m e t r y o f t h e T e r n a r y
S p e c i e s o f 1 2 - M o l y b d a t o p h o s p h a t e
w i t h R h o d a m i n e B
The molar ratio of components in the ion associate
was expressed from the method of continuous variations12.
n
y = 0.1421x + 0.0104 R 2 = 0.9987
X Δ α a 0.40 × 10 –6 mol dm –3 1.24 × 10 –5 g dm –3
X Δ β a 1.18 × 10 –6 mol dm –3 3.66 × 10 –5 g dm –3
X m b 0.79 × 10 –6 mol dm –3 2.44 × 10 –5 g dm –3
X 3σ c 0.83 × 10 –6 mol dm –3 2.56 × 10 –5 g dm –3
ε σ d 142123 ± 3767 mol –1 cm –1 dm 3
x
1− x
max
= .The resulting value of n was n = = 1
max
0,
5
1−
0,
5
Fig. 1. The point 0 on the jobs curve corresponds with the
maximal concentration of the Rhodamine b and zero concentration
of phosphate, the point 1 with the maximal concentration
of phosphate and zero concentration of Rhodamine b. points
belong to the total absorbance of solution, points belong to the
Rhodamine b blank
This molar ratio corresponds with the ratio between phosphate
and Rhodamine B as 1 : 1. Which describes the composition
of the ion associate such as H 2 P[Mo 3 O 10 ] 4 – . RhB + in
1 mol dm –3 H 2 SO 4 .
A p p l i c a t i o n s F o r t h e R e a l S a m p l e s
o f W a t e r
For all kinds of water, the method of standard additions
in six concentration levels which are 1, 2, 4, 6,
7 × 10 –6 mol dm –3 was used. The concentration of phosphate
was found 0.1 ± 0.02 mg dm –3 triplicate the values in the
.
s431
Fig. 2. The supposed structure of the ion associate
river water and 0.16 ± 0.007 mg dm –3 phosphate in the drinking
water. The determination could not be carried out by
this approach for mineral water because of increased contents
of silicate in solution. The optimal concentration of
6.7 × 10 –4 mol dm –3 tartaric acid is not effective for masking
but the necessary higher concentration of tartaric acid would
interfere with the determination of phosphate. The concentration
of phosphate in the analyzed sea water was under the
detection limit and the method of standard addition can not
be used.
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