利用Lyapunov指数在B-Z化学振荡铜(Ⅱ)体系中测定痕量二恶英

王文斌，陈本寿

(重庆化工职业学院，重庆 401228)

利用Lyapunov指数在B-Z化学振荡铜(Ⅱ)体系中测定痕量二恶英

王文斌*，陈本寿

(重庆化工职业学院，重庆 401228)

在本文中，引入最大的Lyapunov(λL)利用B-Z化学振荡Cu(Ⅱ)体系在水相中定量测定了痕量二恶英. 结果表明，最大Lyapunov指数与诱导期的乘积和二恶英浓度的负对数在4.0×10-7～4.5×10-11mol/L浓度范围内线性相关，相关系数为0.998 8(n= 10). 方法的检出限为2.1×10-11mol/L. 此外，还简要讨论了可能的作用机理.

Lyapunov指数；化学振荡体系；二恶英；测定

Biography： WANG Wenbin (1980-), male, lecturer majoring in nonlinear chemistry. E-mail:wwb601@126.com.

Dioxins pollutants mainly include polychlorinated dibenzo PCDDs, PCDFs and PCBs, in addition to a stable, long half-life and high lipophilic metabolic characteristics, in vivo effects to the aryl hydrocarbon receptor (AhR)[1]. Dioxins are highly toxic and widely distributed. Human ingest low dose dioxins through the food chain and enrich them in the body, which is an important way to cause health hazards. Dioxin pollution and its health hazards have caused widespread public concern, and purity analysis is the premise of the work[2]. At present, high performance liquid chromatography is often used for the detection of Dioxin

Since TIKHONOVA[3]et al applied the oscillating reaction to quantitative analysis in 1978, the application of chemical oscillation in analytical test has been developed rapidly. In the current methods in chemical oscillation in the determination of trace substances were reported in three kinds of potential potential diagram method, bifurcation theory, Nata SA Peji C, and maximum Lyapunov index (LEs). The content of trace substances can be analyzed by using oscillatory potential difference methods (such as cycle and amplitude) and measuring the concentration of standard curve. This method is simple and easy operation[4-7]. It was used in most literatures at present. PETER[8]et al introduced the method of judging the attractor type of dynamical systems, Lyapunov index (LEs), into the chemical oscillation system. This method, combined with kinetic system and mathematical method, enables us to judge the method of analyte by static chemical oscillating potential potential diagram. The method is more theoretical and the result is more stable[9].

In this paper, the 8- index was quantitatively detected by Lee Jaap Love index in the B-Z chemical oscillating Cu(II) system, and its detection limit could be up to 10-11mol/L. The method is simple, fast and accurate, and the coexistence ion interference experiment has been done.

1 Experimental part

1.1 Reagents instruments

The reagents used in the experiments were of analytical grade, H2O2(Tianjin Zhiyuan Chemical Reagent Co., Ltd), CuSO4(Tianjin Chemical Reagent Factory three), KSCN (Tianjin Yaohua chemical plant), NaOH (Tianjin chemical reagent factory two), NaCl (Beijing chemical plant), Dioxin (Tianjin kwangfu Institute of fine chemicals), Ultra pure water (SZ-93 automatic double distilled water water distiller, Shanghai Yarong biochemistry instrument factory). Hydrogen peroxide using Potassium Permanganate calibration method. Copper sulfate by Iodimetry potassium thiocyanate with silver nitrate. The calibration method calibration. alibration with sodium hydroxide two formic acid sodium hydrogen phthalate method.

The experiment was conducted by a constant temperature water bath (type 501 super constant temperature water bath, Shanghai experimental instrument factory), fully stirred by magnetic stirring (85-2) in the reactor. The three electrode system (Pt, Pt, potassium sulfate saturated calomel electrode) in Lenovo PC under the support of the software 832b by electrochemical analyzer (Shanghai Chen instrument company) to record the potential difference.

1.2 Experimental method

The maximum Lyapunov exponent is used to determine the state of the system (chaos), and the stability of such states:

λL=1tN-t0∑N-1k=0log2ΔL′(tk+1)ΔL(tk)

Finally the results of -lgCandtlambdaλL* linear fitting.

Fig.1 Chemical oscillation in Cu(II) system

Fig.2 Perturbation of Dioxin to Cu(II) system

Cu(II) system potential potential diagram of induction period is shown in Fig.1. With adding high concentration of dioxin solution sample, the induction period is obvious (Fig.2), and when the concentration of the solution is less than or equal to 10-9mol/L, no obvious induction period.

2 Results and discussion

2.1 Ion detection

The plot of the negative logarithmic line of theλL*Ti product and the added dioxin concentration is as follows.

Fig.3 Negative logarithm linear of λLTi and the concentration of Dioxin

The results showed that in a certain range of concentration,λL*Ti was linearly related to the negative logarithm of dioxin concentration. In the4.0×10-7mol/L to 4.4×10-11mol/L range, the negative logarithm ofλL*Ti concentrations showed a good linear relationship with a correlation coefficient of 0.998 8 (n=10) and a detection limit of 2.1×10-11mol/L.

2.2 Interference by coexisting substances

Because the oscillating reaction system is very sensitive to the environment, small perturbations may lead to change in the system. The possible effects of interfering substances in the determination of dioxins was examined. Under the optimum conditions, the concentration of dioxin is 5.10×10-10mol/L, and the common alkali and alkaline earth metal ions have no influence on the content of Cu2+and Pb2+. The allowable amount of heavy metals and small molecules of organic alcohols, Hg2+and so on is 50-100 times. The results are shown in Table 1.

Table 1 Interference of coexisting substances (Dioxin concentration is 2.500×10-5 mol L-1)

2.3 Mechanism discussion

According to the reaction model of Cu(II) system proposed by ORBAN[6-8]et al, there are 30 reactions and 26 variables. The reaction mechanism is based on two subsystems: ①H2O2oxidation of SCN-; ② Feedback of Cu2 +catalyzed H2O2reaction in strongly alkaline medium. The main reaction mechanism of the oscillating reaction in copper system is the positive and negative feedback loop[3]in the autocatalytic process.

Positive feedback produces yellow cuprous complex compounds [HOO-Cu (Ⅰ)]：

OS(O)CN-+ OOS(O) CN-+ H2O

2OS(O)CN·+2OH-

OS(O)CN-+Cu+[SCN-]n

OS(O)CN-+Cu2++nSCN-

H2O2+Cu2++OH-

HO2-Cu(Ⅰ)+H2O

Yellow disappears in negative feedback：

HO2-Cu(Ⅰ)+nSCN-

Cu2+[SCN-]n+HO2·

OS(O)CN-+HO2·

SO3-·+HOCN

SO3-·+Cu2+[SCN-]n

SO32-+Cu2++nSCN-

Intermediate OS (O) CN-the rate at which the feedback is generated is extremely slow and the initial concentration is extraordinary low.

2OOS(O)CN-+OH-

OS(O)CN-+SO42-+HOCN

When the concentration of OS(O)CN-and Cu2+[SCN]nremains, the intermediate OS(O)CN can be catalytically generated by the formation of radical OS(O)CN·, At the same time, Cu+is oxidized to Cu2+, a yellow complex of cuprous oxide compounds [HOO-Cu(Ⅰ)] present.

Dioxins can form two strong copper oxygen bonds with Cu(II) to form a stable chelate, Thus, when the concentration is large, the Cu2+[SCN]nis replaced by Cu2+[C9H7NO]n, which occurs as follows

HO2-Cu(Ⅰ)+nC9H7NO-

Cu2+[C9H7NO]n+HO2·

To retard the formation of intermediate OS(O)CN-, because the system does not have enough Cu2+-n[SCN], free radical OS(O)CN-not to produce intermediate OS(O)-CN, so the system has long induction time.

3 Conclusion

With lower concentration, dioxins do not prevent the reaction of the system from occurring because there is no absolute superiority in quantity. However, because of the existence of Cu2+and [C9H7NO]n, the system parameters change and cause the system movement to change between the stable and unstable points, which leads to the obvious change of the maximum LEs of the system. It is this change that strongly reflects the application of the greatest Les in quantitative analysis of the advantages of the application.

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date： 2017-01-03.

DeterminationoftraceamountsofDioxinbyusingLyapunovexponentofBelousov-ZhabotinskiioscillatingCu(Ⅱ)

WANG Wenbin*, CHEN Benshou

(ChongqingChemicalIndustryVocationalCollege,Chongqing401228,China)

Using the maximum LEs (λL) in the B-Z Cu(Ⅱ)chemical oscillating system, trace Dioxin was detected quantitatively in aqueous phase. Results showed that the product of the largest Lyapunov exponent and induction period was linearly proportional to the negative logarithm of concentration of Dioxin from 4.0×10-7mol/L to 4.5×10-11mol/L and the correlation coefficients was 0.998 8 (n=10). The detection limit was 2.1×10-11mol/L. In addition, the probably mechanism was discussed in brief.

Lyapunov exponent; oscillating chemical system; Dioxin; determination

O656.3DocumentcodeA

1008-1011(2017)05-0589-04

Project supported by Chongqing Foundation and Frontier Research Project (cstc2016jcyjA0075) Chongqing Higher Education Teaching Reform Research Project (143184)； Chongqing Changshou District Science and Technology Plan Project (cs2017006).

[责任编辑:张普玉]