阅读说明：本技术 高锰酸钾指数的自适应滴定方法 (Self-adaptive titration method for potassium permanganate index ) 是由 徐志伟 胡建坤 唐小燕 丁世潮 姚俊杰 徐炜 任中强 王青青 夏晓峰 刘洋 于 2020-12-30 设计创作，主要内容包括：本发明提供了高锰酸钾指数的自适应滴定方法,包括以下步骤：(A1)向水样中滴入体积V-0的高锰酸钾溶液,并搅拌,搅拌速度为ω,水样的温度为T；获得水样中滴入高锰酸钾溶液到水样颜色消散所需要的时间t；(A2)利用映射关系V＝f(V-0,T,t,ω),获得预测总滴定体积V；若总滴定体积V超过阈值V-m,进入步骤(A3)；若总滴定体积V未超过阈值V-m,进入步骤(A4)；(A3)以第一速度v-1向所述水样中滴入体积为(V-A)的高锰酸钾溶液,A为设定值,并搅拌,进入步骤(A4)；(A4)以第二速度v-2向所述水样中滴入高锰酸钾溶液,v-2＜v-1,直至滴定终点。本发明具有效率高、自动化等优点。(The invention provides a self-adaptive titration method of potassium permanganate index, which comprises the following steps: (A1) dropping volume V into water sample 0 Stirring the potassium permanganate solution at the stirring speed of omega, wherein the temperature of the water sample is T; obtaining the time t required by dripping a potassium permanganate solution into a water sample until the color of the water sample is dissipated; (A2) using the mapping relation V ═ f (V) 0 T, ω) to obtain a predicted total titration volume V; if the total titration volume V exceeds a threshold value V m Entering step (a 3); if the total titration volume V does not exceed the threshold value V m Entering step (a 4); (A3) at a first speed v 1 Dripping a potassium permanganate solution with the volume of (V-A) into the water sample, wherein A is a set value, stirring, and entering the step (A4); (A4) at a second speed v 2 (iv) dropping potassium permanganate solution into the water sample, v 2 ＜v 1 Until the end of the titration. The invention has the advantages of high efficiency, automation and the like.)

1. The adaptive titration method of the potassium permanganate index comprises the following steps:

(A1) dropping volume V into water sample₀Stirring the potassium permanganate solution at the stirring speed of omega, wherein the temperature of the water sample is T;

obtaining the time t required by dripping a potassium permanganate solution into a water sample until the color of the water sample is dissipated;

(A2) using the mapping relation V ═ f (V)₀T, ω) to obtain a predicted total titration volume V;

if the total titration volume V exceeds a threshold value V_mEntering step (a 3);

if the total titration volume V does not exceed the threshold value V_mEntering step (a 4);

(A3) at a first speed v₁Dripping a potassium permanganate solution with the volume of (V-A) into the water sample, wherein A is a set value, stirring, and entering the step (A4);

(A4) at a second speed v₂Dripping potassium permanganate into the water sampleSolution, v₂＜v₁Until the end of the titration.

2. The method for adaptive titration of potassium permanganate index according to claim 1, wherein in step (a 1);

if the time t is more than or equal to t_minEntering step (a 2);

if the time t is less than t_minAdjusting a parameter, said parameter comprising a volume V₀Stirring speed omega or water sample temperature T until time T is more than or equal to T_minThe process proceeds to step (a2), where the adjusted parameter is substituted into the mapping relationship V ═ f (V2)₀，T，t，ω)。

3. The method for adaptive titration of a potassium permanganate index according to claim 2, wherein at time t_minThen, the deviation between the obtained predicted total titration volume V and the actual total titration volume satisfies the detection requirement.

4. The adaptive titration method according to claim 1, wherein the mapping relationship is: v5.24 x 10⁵V₀+1.31*10⁵ω+15.60T-1.11*10^-2t-7.86*10⁷。

5. Method for the adaptive titration of a potassium permanganate index according to claim 1, characterized in that the set value a and the second speed v₂The relationship between (A) and (B) is: a is more than or equal to 10v₂。

6. The adaptive titration method according to claim 1, characterized in that the threshold V is_mAnd a second speed v₂The relationship between (A) and (B) is: v_m≥40v₂。

7. The method for adaptive titration of a potassium permanganate index according to claim 1, wherein the first speed v₁And a second speed v₂The relationship between (A) and (B) is: v. of₂＜0.1v₁。

8. The method for adaptive titration of potassium permanganate index according to claim 1, wherein the time t is obtained with a color sensor.

9. The adaptive titration method according to claim 1, wherein the mapping is corrected using the actual total titration volume.

10. The adaptive titration method for potassium permanganate index according to claim 1, wherein the temperature of the water sample is directly detected, or the temperature of the water sample cup is detected, thereby indirectly obtaining the temperature of the water sample.

Technical Field

The invention relates to water sample detection, in particular to a self-adaptive titration method of potassium permanganate index.

Background

Manual titration and automatic titration of the water quality permanganate Index (IMN) need to judge whether the titration end point is reached or not while carrying out titration, and the detection takes longer time.

According to the national standard GB11892-1989, the existing detection method of permanganate index adopts a method of heating a water sample in water bath and titrating potassium permanganate. The method needs manual operation and comprises the steps of quantitatively adding 100ml of water sample into a conical flask, quantitatively adding various chemical reagents, timing in a water bath for 30min +/-2 min, manually carrying out potassium permanganate titration, judging titration results by naked eyes and the like. And (3) during the dripping, keeping the temperature of the water sample at 60-80 ℃, titrating with a potassium permanganate solution until the water sample just turns pink, and keeping the water sample from fading for 30s to determine as an end point. The permanganate index was calculated from the volume of potassium permanganate solution consumed for the titration.

The manual titration process depends on the experience of an analyst, and a large system error is brought in the aspect of judging the stability of a titration result by naked eyes, so that the accuracy of the analysis result is low and the consistency is poor. In addition, the manual analysis also brings the defects of complex operation, labor consumption and the like.

In recent years, various titrators are successively introduced in the market, so that the automatic titration and detection of the permanganate index can be performed, and the workload of manual operation is reduced. Most of the devices adopt a heating component to carry out water sample heat preservation during dripping; a magneton stirrer is adopted for stirring the water sample during the dripping, so that the reaction of potassium permanganate and the water sample is promoted; and (3) detecting the titration end point by adopting various detection elements such as an ORP electrode, an absorbance sensor and the like. At higher sample volumes, such titrators also expose technical problems, such as:

1. because the constant-speed titration is adopted, namely, the titration is carried out drop by drop in a mode of dropping one drop at fixed intervals, the consumed time is long, and the analysis efficiency is low.

2. Because the heating plate heat preservation mode is adopted, the temperature of the water sample is not directly monitored, and the temperature of the water sample possibly exceeds the temperature range required by the national standard in different temperature, humidity and ventilation environments, so that the accuracy of a measurement result is influenced.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides the self-adaptive titration method of the potassium permanganate index, which has high titration efficiency, automation and good accuracy.

The purpose of the invention is realized by the following technical scheme:

the adaptive titration method of the potassium permanganate index comprises the following steps:

(A1) dropping volume V into water sample₀Stirring the potassium permanganate solution at the stirring speed of omega, wherein the temperature of the water sample is T;

obtaining the time t required by dripping a potassium permanganate solution into a water sample until the color of the water sample is dissipated;

(A2) using the mapping relation V ═ f (V)₀T, ω) to obtain a predicted total titration volume V;

if the total titration volume V exceeds a threshold value V_mEntering step (a 3);

if the total titration volume V does not exceed the threshold value V_mEntering step (a 4);

(A3) at a first speed v₁Dripping a potassium permanganate solution with the volume of (V-A) into the water sample, wherein A is a set value, stirring, and entering the step (A4);

(A4) at a second speed v₂(iv) dropping potassium permanganate solution into the water sample, v₂＜v₁Until the end of the titration.

Compared with the prior art, the invention has the beneficial effects that:

in order to overcome the defects in the prior art, the applicant proposes a variable-speed titration method: based on the predicted total titration volume (obtained in a variety of ways), the titration end point is approached at a higher titration rate and then reached at a lower titration rate. Based on the inventive concept, the following effects are achieved:

1. the titration efficiency is high;

according to the parameters (total titration volume V, stirring speed omega, dissipation time T, temperature T of the mixed liquor and volume V₀) The relationship between the two is scientifically obtained and predicted total titration volume (obtaining mode is various) and the first speed v is higher₁Approaching the end point of the titration, and then at a second, lower speed v₂The titration end point is reached, and the titration efficiency is obviously improved;

2. automation;

automatically detecting the stirring speed omega, the dissipation time T, the temperature T and the volume V of the mixed liquid₀The predicted total titration volume is obtained by utilizing the parameters, the dissipation time is automatically obtained by utilizing the color sensor, and then whether the titration end point is reached or not is automatically judged, so that the whole process automation is realized;

3. the accuracy is good;

monitoring the temperature of a water sample, performing closed-loop temperature control on the water sample, ensuring that the water temperature meets the national standard during dripping, solving the problem of inaccurate open-loop control of the temperature of the water sample, and enabling the titration data to be more accurate;

through carrying out color recognition on a water sample in the titration process, a titration end point algorithm is adopted, the permanganate index result is accurately analyzed, and the data accuracy and consistency are good.

Drawings

The disclosure of the present invention will become more readily understood with reference to the accompanying drawings. As is readily understood by those skilled in the art: these drawings are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of the present invention. In the figure:

fig. 1 is a flow chart of a method for adaptive titration of potassium permanganate index according to an embodiment of the present invention.

Detailed Description

Fig. 1 and the following description depict alternative embodiments of the invention to teach those skilled in the art how to make and reproduce the invention. Some conventional aspects have been simplified or omitted for the purpose of teaching the present invention. Those skilled in the art will appreciate that variations or substitutions from these embodiments will be within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. Thus, the present invention is not limited to the following alternative embodiments, but is only limited by the claims and their equivalents.

Example 1:

fig. 1 schematically shows a flow chart of an adaptive titration method for potassium permanganate index according to an embodiment of the present invention, and as shown in fig. 1, the adaptive titration method for potassium permanganate index includes the following steps:

(A1) dropping volume V into water sample₀Stirring the potassium permanganate solution at the stirring speed of omega, wherein the temperature of the water sample is T;

obtaining the time t required by dripping a potassium permanganate solution into a water sample until the color of the water sample is dissipated;

(A2) using the mapping relation V ═ f (V)₀T, ω) to obtain a predicted total titration volume V;

if the total titration volume V exceeds a threshold value V_mEntering step (a 3);

if the total titration volume V does not exceed the threshold value V_mEntering step (a 4);

(A3) at a first speed v₁Dripping a potassium permanganate solution with the volume of (V-A) into the water sample, wherein A is a set value, stirring, and entering the step (A4);

(A4) at a second speed v₂(iv) dropping potassium permanganate solution into the water sample, v₂＜v₁Until the end of the titration.

In order to accurately obtain the predicted total titration volume and improve the titration efficiency, further, in step (a 1);

if the time t is more than or equal to t_minEntering step (a 2);

if the time t is less than t_minAdjusting a parameter, said parameter comprising a volume V₀Stirring speed omega or water sample temperature T until time T is more than or equal to T_minThe process proceeds to step (a2), where the adjusted parameter is substituted into the mapping relationship V ═ f (V2)₀，T，t，ω)。

To improve accuracy, further, at time t_minThe obtained prediction sumThe deviation between the titration volume V and the actual total titration volume meets the detection requirement; for detection, the tolerance to the deviation is different, corresponding to the deviation, time t_minAnd also different.

In order to obtain the mapping relationship, the mapping relationship can be obtained through experiments, data fitting and other modes, the adopted modes are different, the expression forms of the obtained mapping relationship are different, and the precision is also different; the mapping relation is as follows: v5.24 x 10⁵V₀+1.31*10⁵ω+15.60T-1.11*10^-2t-7.86*10⁷。

In order to reach the titration endpoint more quickly, further, the set value A and the second speed v₂The relationship between (A) and (B) is: a is more than or equal to 10v₂。

In order to better embody the technical advantages of the technical solution, further, the threshold V is_mAnd a second speed v₂The relationship between (A) and (B) is: v_m≥40v₂。

To increase the efficiency of the titration, further, the first speed v₁And a second speed v₂The relationship between (A) and (B) is: v. of₂＜0.1v₁。

In order to automatically and accurately obtain the dissipation time t, further, the color change of the water sample is monitored by using a color sensor, so that the time t is obtained.

In order to further improve the titration efficiency and accuracy, the actual total titration volume is further used to correct the mapping.

In order to further improve the accuracy, further, the temperature of the water sample is directly detected, or the temperature of the water sample cup is detected, thereby indirectly obtaining the temperature of the water sample.

Example 2:

an application example of the adaptive titration method of potassium permanganate index according to embodiment 1 of the present invention.

In the application example, the base is used for heating the water sample cup, and the temperature of the water sample cup is monitored, so that the temperature of a water sample is indirectly obtained; magnetic stirring is adopted, a stirrer is positioned in the water sample cup, and a motor is arranged at the lower side of the heating base; monitoring the color of the water sample by a color sensor, and recording the time by a timer; and (3) dropping a determined volume of potassium permanganate solution into the water sample by using a combination of a pump and a valve.

The adaptive titration method for the potassium permanganate index comprises the following steps:

(A1) dripping a potassium permanganate solution with the volume of V0 into the water sample, and stirring, wherein the stirring speed is omega, and the temperature of the heated water sample is T, so that the national standard requirement is met;

obtaining the time t required by dripping a potassium permanganate solution into a water sample until the color of the water sample is dissipated;

if the time t is more than or equal to t_minEntering step (a 2); at time t_minThen, the deviation between the obtained predicted total titration volume V and the actual total titration volume meets the detection requirement; for detection, the tolerance to the deviation is different, corresponding to the deviation, time t_minAlso different;

if the time t is less than t_minAdjusting a parameter, said parameter comprising a volume V₀Stirring speed omega or water sample temperature T until time T is more than or equal to T_minEntering step (a2), substituting the adjusted parameter (meeting the national standard requirement) into the mapping relationship V ═ f (V)₀，T，t，ω)；

(A2) According to (fitting with data) the mapping V-5.24 x 10⁵V₀+1.31*10⁵ω+15.60T-1.11*10^{- 2}t-7.86*10⁷Obtaining a predicted total titration volume V;

if the total titration volume V exceeds a threshold value V_mIn this embodiment, V_mStep (a3) is entered when the volume is 1 mL;

if the total titration volume V does not exceed the threshold value V_mEntering step (a 4);

(A3) at a first speed v₁Continuously dropping a potassium permanganate solution with the volume of (V-A) into the water sample, setting the A value to be 0.5mL, stirring, and entering the step (A4);

(A4) at a second speed v₂(vi) dropping a potassium permanganate solution into the water sample at 25. mu.L/s, v₂＜v₁Until the end point of titration;

the actual total titration volume is used to correct the mapping.

Example 3:

the application example of the adaptive titration method for potassium permanganate index according to embodiment 1 of the present invention is different from embodiment 2 in that:

1. the temperature sensor is arranged in the water sample cup to directly obtain the temperature of the water sample.

2. Mapping relationships

V＝(-5.50*10^-3V₀+3.96*10^-4ω+9.34*10^-3T-4.16*10^-10t+2.81*10^-5V₀ ²-7.71*10^-7ω²-9.88*10^-5T²+7.01*10^-13t²)*(V₀*ω*T*t)+0.65

The fitting order of (2) is higher, and the precision is higher.

The core of the technical scheme of the patent application is as follows: with the variable rate titration method, the mapping is obtained for variable rate titration.