Method for measuring pH value of aqueous solution

An aqueous solution and solution technology, which is applied in the direction of material analysis by observing the influence of chemical indicators, and analysis by making materials undergo chemical reactions. Accurate, improve accuracy and linear relationship, effective screening effect

Active Publication Date: 2021-07-13

BEIJING NORMAL UNIVERSITY

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AI-Extracted Technical Summary

Problems solved by technology

The degradation process of AuNRs seriously affects its precision and a...

Abstract

The invention relates to a method for measuring the pH value of an aqueous solution based on gold nanorods, and belongs to the technical field of nano materials. The method comprises the following steps: (A) adding a gold nanorod solution and an etching solution into a to-be-detected solution, and then continuously monitoring RGB color space values of the solution corresponding to red, green and blue color component values until the etching reaction is finished; (B) converting the GRB color space value into a hue value; (C) mapping the tone value to the etching reaction time in the polar coordinate system to obtain a reverse value of the tone within 400 seconds after the etching is started and a maximum forward rotation value in the whole etching process; and (D) when the reverse rotation value is less than 38 degrees, substituting the maximum forward rotation value of the hue value into the correction curve to realize the measurement of the pH value. According to the method provided by the invention, the quality of the gold nanorod is discriminated through the reversal value in the measurement process, and unqualified colorimetric probes are removed, so that the measurement precision and accuracy are remarkably improved.

Application Domain

Material analysis by observing effect on chemical indicator

Technology Topic

Color toneEtching +8

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Examples

Experimental program(5)
Effect test(1)

Example Embodiment

[0036] Example 1

[0037] 1.1 Preparation of Golden Nice Rods

[0038] The AUNRs used in this note is prepared by seed synthesis.

[0039] The seed solution is prepared by the following steps: 25 μl of Haucl to mix in 25 ml round bottom flask 4 (50 mm) and 5 mlctab (0.1m). After stirring for 5 minutes, add 300μL NABH for fresh preparation 4 Ice solution (0.01 m) and then stirred vigorously for 30 seconds. Finally, it was incubated in a water bath placed at 30 ° C to obtain a seed solution.

[0040] The preparation method of the growth solution is as follows: 200 μl of HCl (1M), 100 μL Haucl 4 (50 mm) and 10 ml of CTAb (0.1m) were added to 50 ml of glass round bottom flask and gently stir. Finally, add 120 μl of AgNO 3 (10 mM) and 100 μL of ascorbic acid (100 mM) can be obtained to produce seed growth fluids.

[0041] When AunRs were prepared, 24 μl seed solution was injected into the seed growth liquid and stirred vigorously for 30s, and then incubated in a water bath at 30 ° C for 24 hours to wait for its growth. 10 ml of AunRS centrifugation (10,000 rpm), washed twice using ultrapure water, and finally dispersed in 2 ml of CTAb (10 mm).

[0042] 1.2 Gold nano

[0043] AunRS is characterized using a TF20 transmission electron microscope. figure 1 Displayed, the synthesized gold nano rod length is about 40 nm, a diameter of about 10 nm, and a newly synthetic AUNRS shape is constituished.

Example Embodiment

[0044] Example 2

[0045] This embodiment uses the AUNRS synthesized by Example 1 for detection of pH. The AunRS solution is freshly prepared, and the solution to be tested is a standard solution having a pH of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, etching liquid by 3.3 mm ki and 6.6MH. 2 O 2 composition.

[0046]100 μl of AUNRS solution and 100 μl of etching solution were added to a solution of 800 μl of different pH, and the mixed into the cuvette, the etching temperature was 1500s, using TCS3200 color sensor (Taos Company) , USA) Monitoring, continuously collecting RGB signals, converting RGB values into color value h in the following formula H

[0047]

[0048] Equation (1) R, G and B are red, green and blue components, MAX channel And MIN channel It is the maximum and minimum intensity in red, green and blue channels.

[0049] As a colorimetric probe with newly presumed AUNRS, the color adjustment value - the reaction time is drawing in the polar coordinates, and it is found that it is a clockwise direction (down), the curve is smooth, the resolution is good, and there is no counterclockwise in the middle Direction process ( figure 2 ). The maximum tone value is made to the pH, and it can be found that there is good linearity in the range of pH = 1-7. image 3 ), Correlation coefficient r 2 = 0.987, the linear equation is Y = -38.22x + 427.34 (where x is pH, Y is the color value).

[0050] will image 3 The pH value of the medium is compared to the calculated value of the correction curve, the resulting deviation value is listed in Table 1, and the results show that the maximum deviation of the linear correction curve is 0.281 as the pH value is measured as a colorimetric probe. The pH unit, which is high with the correction curve.

[0051] Table 1 Experimental data for freshly prepared AunRs colorimetric probes

[0052]

Example Embodiment

[0053] Example 3

[0054] This embodiment is measured as a colorimetric probe after a long-term temperature-placed (aging) for a long time.

[0055] The synthesized AunRs in Example 1 was placed at room temperature for 25 days, and it was used as a colorimetric probe using the same conditions as in Example 2. Measurement of the pH value. Experiment found that the AUNRS placed in 25 days showed different response patterns ( Figure 4 ), Its response is rotated counterclockwise in the initial stage, and then rotate clockwise after 400s. This phenomenon is consistent with each test pH. Overall, the resolution between the change curve is poor.

[0056] The maximum tone value is made to the pH, and it can be found that the linear relationship is poor in the range of pH = 1-7. Figure 5 ), The calibration curve has a lower linear correlation coefficient (R 2 = 0.927, less than 0.95), the linear equation is Y = -23.96X + 368.72. As compared with the freshly prepared AunRs in Example 2, the aging AunRS was measured as a probe to measure the absolute value of the slope of the aqueous solution pH value, indicating that the sensitivity is lowered.

[0057] will Figure 5 The highly measured pH is compared to the value of the calibration curve, the deviation value is obtained in Table 2, and the results show that the AUNRS of 25 days after 25 days is placed as a colorimetric probe to measure the pH value, the maximum deviation of the linear correction curve is 1.00. The pH unit, and the correction curve meets the difference. will Figure 4 The reverse value in 400s is included in the table, and it is found that the reverse value in the polar coordinate system is 156.9 ° ~ 168.2 °.

[0058] Table 2 Laboratory data of 25 days of AunRS coloror probe

[0059]

[0060] TEM characterization was performed on the AUNRS in this embodiment, found that these Aunrs after 25 days have deteriorated, only 52.9% of nanoparticles are rods, 30.2% transition to nano-cubic, while the remaining 16.9% is irregular nano structure. Since the nano-cubic and irregular nanostructure optical properties have a significant difference from nanorods, the AUNRS is not suitable as a colorimetric sensor for measuring pH.

PUM

Property	Measurement	Unit
Length	40.0	nm
Diameter	10.0	nm

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

effective screening

Method for measuring pH value of aqueous solution

An aqueous solution and solution technology, which is applied in the direction of material analysis by observing the influence of chemical indicators, and analysis by making materials undergo chemical reactions. Accurate, improve accuracy and linear relationship, effective screening effect

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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