Buffer Preparation Using Conductivity Feedback for pH Control
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Solution Overview
Problem
Current pH measurement methods for buffer solutions are inaccurate, time-consuming, and prone to contamination, with pH meters having slow responses and being sensitive to temperature, limiting the reliability of pH control in chemical applications.
Innovation Solution
A method that indirectly determines pH by using a surface model equation correlating conductivity and concentration, allowing for the preparation of buffer solutions with a predetermined pH without a pH meter by controlling buffer component additions based on specific conductivity values, using conductivity as a feedback control parameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pH meters are used to measure and control pH, then pH measurement capability is provided, but the measurement accuracy is limited, response is slow, and contamination occurs
Solution Approach 1:
The patent uses conductivity as an intermediary parameter to indirectly determine pH. Instead of directly measuring pH with a pH meter, the system measures conductivity (which is more reliable and faster) and uses a pre-established mathematical model to calculate pH from the conductivity value, thereby avoiding the limitations of direct pH measurement
Solution Approach 2:
The patent replaces the mechanical/electrochemical pH meter system with an electrical conductivity measurement system combined with mathematical calculation. This substitution eliminates the need for pH electrode calibration and reduces contamination issues while providing faster response times
2Ease of operation
If pH meters are used for pH measurement, then pH control is possible, but calibration is time-consuming and troublesome
Solution Approach 1:
The patent performs preliminary action by pre-establishing a mathematical model that correlates conductivity with pH for specific buffer systems. This model is created beforehand through regression analysis of training data, so that during actual operation, only conductivity needs to be measured and the model automatically provides pH, eliminating the need for time-consuming calibration procedures
Solution Approach 2:
The system uses itself to determine pH through conductivity measurement and mathematical calculation, without requiring external calibration standards or manual intervention. The conductivity measurement and pH calculation are performed automatically by the system itself, making the process self-sufficient and eliminating calibration steps
3Temperature
If pH meters are used, then pH measurement is provided, but temperature corrections are required and readings cannot be corrected to standard temperature
Solution Approach 1:
The patent uses conductivity as an intermediary that can be more easily temperature-corrected than direct pH measurements. Conductivity measurements and their corresponding pH values from the training dataset are all temperature-corrected to a standard temperature (e.g., 25°C), allowing the mathematical model to provide temperature-independent pH values without requiring complex temperature corrections during operation
4Manufacturing precision
If buffer components are added to achieve predetermined pH, then pH control is possible, but frequent calibration and temperature corrections are needed
Solution Approach 1:
The patent implements feedback control by measuring conductivity during buffer preparation, using the mathematical model to calculate the current pH, comparing it with the target pH, and automatically adjusting buffer component additions accordingly. This closed-loop feedback system maintains pH accuracy without requiring frequent manual calibration or temperature corrections, as the system self-corrects based on real-time conductivity measurements
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 approach provides a reliable and efficient method for maintaining constant pH in buffer solutions, reducing the need for frequent pH meter calibration and temperature corrections, while ensuring accurate pH control through conductivity measurements.
Implementation Method 1
wherein said specific conductivity value is correlated to said predetermined pH value and the buffer concentration by a mathematical model
Data Source
AI summary
The present invention relates to the preparation of liquid mixtures, and more particularly to the preparation of a liquid mixture, such as a buffer, wherein the conductivity of the liquid mixture is measured and the pH indirectly determined if the buffer concentration is known. Another object of the present invention is to provide a method of preparing a liquid mixture with a predetermined pH value by using conductivity as feedback control parameter.