Acidity Measurement Using pH-Sensitive Dye Spectroscopy
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Solution Overview
Problem
Conventional methods for measuring the total and free acidity of aqueous solutions containing strong acids and hydrolyzable cations are inefficient, especially at high concentrations, and often require alkaline titrants, making them unsuitable for industrial processes like hydrometallurgy and chemical acid pickling.
Innovation Solution
A method using a pH-sensitive dye to determine the total acidity of an aqueous solution by exploiting its turning zone, without the need for acid-base titration, allowing for precise measurement of protons through UV-visible absorbance spectroscopy, and a separate process for determining free acidity by complexing hydrolyzable cations, enabling accurate assessment of acidity in industrial processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pH-metry methods are used to measure total acidity, then measurement can be performed, but the method becomes unsuitable at high acid concentrations
Solution Approach 1:
The invention changes the measurement parameter from direct pH measurement (which fails at high concentrations) to spectrophotometric measurement of dye absorbance. By using a pH-sensitive dye whose absorbance characteristics change with pH, the method can accurately measure total acidity in high concentration solutions where conventional pH-metry becomes unsuitable.
2Measurement precision
If alkaline titration is used to determine free acidity, then measurement can be performed, but the process becomes complex and requires additional reagents
Solution Approach 1:
The invention extracts and measures only the free acidity component by using a pH-sensitive dye that responds specifically to free protons. By adding a complexing agent to mask hydrolyzable cations, the method isolates the free acidity measurement from total acidity, eliminating the need for complex alkaline titration procedures while maintaining measurement precision.
Solution Approach 2:
The invention replaces the mechanical/chemical titration process with a spectrophotometric measurement system. Instead of using alkaline titrants and monitoring pH changes during titration, the method uses UV-visible absorbance spectroscopy to directly measure the concentration of free protons through the dye's absorbance characteristics, simplifying the measurement process.
3Measurement precision
If conventional titration methods are used, then acidity can be determined, but large volumes of samples and effluents are required
Solution Approach 1:
The invention replaces volumetric titration with spectrophotometric measurement, which requires much smaller sample volumes. The UV-visible absorbance measurement can be performed on micro-scale samples, and the method generates minimal effluent compared to conventional titration that requires large volumes of titrant and produces significant waste.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for precise and economical measurement of total and free acidity in acidic aqueous solutions, reducing sample and effluent volumes, and is simpler to implement, with minimal reagent use, achieving high accuracy and applicability in industrial settings.
Implementation Method 1
determining the UV-visible absorbance spectrum of the dye present in the solution A5
Implementation Method 2
a pH-sensitive dye, having an acid form and a basic form, and a turning zone between a first pH and a second pH
Implementation Method 3
complexation of hydrolyzable cations by potassium oxalate
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to methods for determining the acidity of an acidic aqueous solution. These methods allow measurement of the total acidity of an aqueous solution comprising a strong acid or a mixture of strong acids and, if this solution contains one or more hydrolysable cations, also allow the free acidity thereof to be measured. Applications: any industrial field and any field of scientific research in which it may be desirable to measure the total acidity or the free acidity of aqueous solutions of strong acids.