Cu(Ⅱ)−SBTを用いた水中シアン化物イオン定量試験紙

Kogakuin University
工学院大学研究報告第 110 号平成 23 年 4 月
Cu(Ⅱ)−SBT を用いた水中シアン化物イオン定量試験紙の開発
斧大介 a，山本悠二 a，中島健二 a，
長島珍男 b，釜谷美則 c，中野信夫 d
Development of a Coloring paper filter to detect a Cyanide ion
in Water using Cu(Ⅱ)−SBT
Daisuke ONOa, Yuuji YAMAMOTOa, Kenji NAKASHIMAa,
Kunio NAGASHIMAb, Minori KAMAYAc and Nobuo NAKANOd
要旨
水中のシアン化物イオン（3 ml/min）を，希硫酸と混合することにより連続的にシアン化水素に変化させ，気
液分離管を用いて試料液から分離した．分離されたシアン化水素を，定量試験紙（直径 12mm 円形）に透過・吸
収・反応させ試験紙をシアン化物イオンの濃度に応じて呈色させた．呈色度は光（λ＝675nm）の反射吸光度か
ら求めた．定量試験紙には，発色剤としての SBT，酢酸銅 (Ⅱ) およびグリセリンが含まれている．気液分離時間
が 5 分間，試料量が 15ml で水中のシアン化物イオン（0.02∼0.2mgCN/L）が定量できた．
salt (SBT)11，12）had been reported. The SBT was applied to
１．Introduction
colorimetric determination of chlorine in water. The molar
Cyanogens compound is highly toxic and is often pro-
reflection absorbance coefficient of SBT was 6.5times as
duced as industrial waste from metal plating, precious metal
that of DPD when the color was developed on the paper fil-
1）
extraction and acrylonitrile manufacture . A threshold limit
2）
−
ter. In addition, the cytotoxicity test showed that LD50 val-
value of 1 mg CN /L of total cyanogens for industrial liq-
ues of SBT and DPD for HeLa cells were 13.5mM and
uid waste is established in Japan. Various methods have
0.05mM, respectively10）. The aqueous stability of SBT is
been reported for the determination of cyanogens com-
higher than that of DPD10）.
pound, including ion selective electrodes, ion chromatogra-
In this paper, SBT was studied as the coloring reagent of
3）
−5）
phy and pyridine−pyrazolone absorption spectrometry
.
coloring paper filter instead of DPD.
This method mentioned here is composed of gas−liquid
２．Experimental
separation, collection of separated HCN gas on the filter
and reflectiometry of color stain produced on the filter.
The filter method
6，
7）
is high sensitivity, a short measure-
ment time and low running cost. The filter using N,N−di8）
ethyl−p−phenylenediamine (DPD) as the coloring reagent
2.1 Reagents and Samples
All chemicals used were of analytical−reagent grade and
were used without further purification.
A processing solution was prepared as follows.
. In 2003, the synthesis meth-
To approximately 70mL of methanol, 0.40g of SBT and
od for N,N´−bis (2,4−di−sulfobenzyl) tolidine tetra sodium
0.10g of Copper(Ⅱ) acetate anhydrous and 30g of glycerin
9，
10）
had been already reported
were added. The mixture was diluted to 100ml with methaa
b
c
d
Master, Graduate School of Applied Chemistry and Chemical Engineering, Kogakuin University
Professor, Department of Environmental and Energy Chemistry,
Kogakuin University
Associate Professor, Department of Environmental and Energy
Chemistry, Kogakuin University
Riken Keiki Co.,Ltd.
nol.
Standard CN− solution (0.01∼0.3mgCN/L) were prepared by dissolving of KCN with pure water.
2.2 Coloring paper ﬁlter
The cellulose tape (Whatman, 1 chr papers, 20mm wide,
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0.18mm thick) was immersed in the processing solution for
5 min, and then placed in desiccator filled with nitrogen gas.
The half dried paper filter was stamped out in 12mm of diameter. The stamped out filter was set with the filter holder
in use.
2.3 Coloring mechanism
The SBT oxidation reaction is shown in Fig. 1. When the
N2 gas including HCN passes through the filter, the HCN
gas reacted with Cu(Ⅰ) ion, but did not react with Cu(Ⅱ)ion.
The oxidation potential of Cu(Ⅱ) was increased when the
Cu(Ⅰ) ion was taken up through the formation of insoluble
CuCN (Ksp is 3.2×10−20). That is, as the value of［Cu(Ⅱ)/
Cu(Ⅰ)］potential equal to the value of［SBTOx / SBTRe］po-
Fig. 1 Oxidation reaction of SBT
tential, a part of Cu(Ⅱ) should change to Cu(Ⅰ) ion by the
decrease in［Cu(Ⅰ)］. Then, the SBTRe can be oxidized to a
the mixture flew into Porous PTFE tube (F−3015 Flon In-
blue compound SBTOx by Cu(Ⅱ)．
dustry Co., i.d. 1.0mm, o.d. 2.0mm) in Gas−Liquid separa-
The color change was recorded by measuring the reflec-
tion tube. Hydrogen cyanide that evolved from the porous
tion absorbance at 675nm. The reflection absorbance was
PTFE tube was purged by nitrogen gas of cylinder.
−
related to the concentration of CN in sample solution at a
The HCN−including nitrogen gas was passed through the
constant sampling time and constant flow−rate of sample
paper filter at a constant flow rate (700ml/min) and a con-
solution.
stant sampling time (5 min).
Cu(AcO)2
2Cu ＋
2＋
＋
Cu ＋2AcO
2＋
SBTRe
(Colorless)
−
＋
⑴
2Cu ＋ SBT
(Blue)
2＋
Ox
⑵
−
Cu ＋CN →CuCN
⑶
2.4 Apparatus
As the flow rate of nitrogen gas increase the SBT Ox
formed on paper filter is moved to the inner of filter, high
flow rate cause the lose of good relationship between concentration of CN− and response (absorbance).
When the HCN gas reacted with the paper filter, the pa-
The experimental apparatus is shown in Fig. 2.
per filter was colored homogeneously in 8 mm of diameter.
In this system, cyanide ion solution (3.0ml/min) and
The degree of color intensity was recorded by measuring
0.054mol/L sulfuric acid (2.0ml/min) were pumped and
the reflected light of wavelength 675nm. The tungsten
mixed by using Perista Pump (SJ−1211H ATTO Co.). Then,
lump was used as light source.
Fig. 2 Experimental apparatus
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Cu(Ⅱ)−SBT を用いた水中シアン化物イオン定量試験紙の開発
３．Results and Discussion
9
glycerin in the processing solution on response is shown in
Fig. 4.
The HCN in N2 was trapped by the filter and reacted with
Maximum response was obtained between 18−30g of
Cu(Ⅰ) ion producing CuCN. The coloring reaction was de-
glycerin in 100ml methanol. The processing solution used
veloped on the surface of paper filter which was supporting
was prepared with a glycerin concentration of 30g/100ml.
the Cu(Ⅱ)−Cu(Ⅰ) ion, SBTRe and H2O−glycerin. The best
As the high concentration of glycerin causes the much
combination of the concentration of Cu(Ⅱ)−Cu(Ⅰ) ion, SB-
glycerin present between CN−, Cu(Ⅰ)，Cu(Ⅱ) and SBT,
TRe and H2O−glycerin was needed to obtain the suitable col-
the efficiency of coloring reaction was decreased.
oring reaction for HCN measurement.
3.1 Concentration of SBT
3.3 Concentration of Copper(Ⅱ) acetate
The relation between the reflection absorbance and the
The effects of the concentration of the SBT in the pro-
concentrations of 0−1.0g/100mL Cu(Ⅱ) acetate in the pro-
cessing solution on the reflection absorbance were studied
cessing solution were investigated (Fig. 5).
to obtain the optimum conditions. The concentrations of
0.10, 0.40 and 1.00g SBT/100mL in the processing solution
were investigated. The effect of the concentration of SBT
in the processing solution on calibration curves is shown in
Fig. 3.
Maximum response was obtained at 0.40g SBT/100ml.
Thus, the processing solution used was prepared with a
concentration of 0.40g SBT/100ml. The high concentration
of SBT causes the much SBT present between CN− and
Cu(Ⅰ), then the efficiency of CN− with Cu(Ⅰ) reaction was
decreased.
3.2 Concentration of Glycerin
Sufficient humectant in the filter was essential in order
to obtain an adequate response to HCN gas. Glycerin was
used as humectant to provide sufficient moisture for the desired reaction of SBT. The effect of the concentration of
Fig. 3 Eﬀect of SBT content on calibration curves
Fig. 4 Eﬀect of glycerin content on reﬂection absorbance
Fig. 5 Effect of copper acetate content on reflection absorbance
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Maximum response was obtained at 0.10g Cu(CH3COO)2 /
100ml. Thus, the processing solution used was prepared
with a Cu(Ⅱ) acetate concentration of 0.10g/100ml.
As the concentration of Cu(Ⅰ) decrease, the sensitivity of
the value of Cu(Ⅱ)/Cu(Ⅰ) to the CN− in sample increase.
But, to obtain stoichiometric formation of SBTOx a some degree concentration of Cu(Ⅱ) acetate on the filter was needed.
3.4 Absorption spectra of colored ﬁlter
Reflection absorption spectra of the surface of filter are
shown in Fig. 6 using the optimum experimental conditions.
The concentrations of CN− in sample solution were between 0−0.15mgCN/L. The maximum wavelength of reflection absorbance is shown at 675nm (Fig. 6).
3.5 Calibration curves
Fig. 7 Calibration curves for cyanide ion
Typical calibration curves for CN−1 ion using the optimum experimental conditions are shown in Fig. 7. The de-
Table 1 Relation between storage time and response
tection limit (signal−to−noise ratio＝3) was 9.4μgCN/L.
Reproducibility tests showed that the coefficient of varia-
Storage time (day)
tion was 1.5% for 0.2mgCN/L. The calibration curve using
0
5
10
50
DPD is shown in Fig. 7. The ratio of absorbance of curve
(SBT) to that of curve (DPD) was 6.3 at the concentration
of 0.20mgCN/L.
Response
Room temperature
5℃
0.257
0.197
0.147
0.110
0.257
0.257
0.254
0.228
CN−＝0.05mg・L−1 (n＝3)
3.6 Long−term stability
Relation between storage time and the response of coloring paper filter was investigated (Table 1). After storage for
４．Conclusion
about 50days in a dark clean box filled with N2, at 5℃，the
decrease of the response to CN−1 was less than 11.3% of
original response.
In conclusion, the coloring paper filter using SBT and
Cu(Ⅱ) acetate was very suitable for the determination of CN
−1
in the range 0.02−0.20mgCN/L. This method is easy to
operate, high sensitivity and low running cost.
References
Fig. 6 Reﬂection absorption spectra of surface of tablet
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Cu(Ⅱ)−SBT を用いた水中シアン化物イオン定量試験紙の開発
11
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