Optical Total Organic Carbon Measurement Using 254 nm Absorption
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Solution Overview
Problem
Current methods for measuring Total Organic Carbon (TOC) in aqueous streams are cumbersome, require skilled operators, use environmentally unfriendly chemicals, are time-consuming, and are not suitable for continuous monitoring due to issues like particle scattering and complex compound interference, especially in the UV-visual spectrum.
Innovation Solution
An optical method using a 193 nm illumination probe and filtered detection at the same wavelength, combined with a pulsed light source and adjustable path length, allows for direct application of the Beer-Lambert Law to calculate TOC concentrations without ancillary measurements, enabling real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NDIR analyzers with chemical oxidation are used to measure TOC, then measurement accuracy is achieved, but the system becomes cumbersome, requires skilled operators, uses environmentally unfriendly chemicals, and is not suitable for continuous monitoring
Solution Approach 1:
The patent replaces the mechanical/chemical oxidation system with an optical measurement system. Instead of using chemical reagents and thermal oxidation chambers, the invention uses UV-Vis spectroscopy to directly measure TOC concentrations through optical absorption, eliminating the need for complex chemical processing hardware
Solution Approach 2:
The patent extracts and eliminates the chemical oxidation step from the TOC measurement process. By using direct optical absorption measurement at 254 nm, the method removes the need for chemical reagents, heating elements, gas flow systems, and associated calibration hardware, simplifying the overall system
2Productivity
If UV absorption measurement is used for TOC determination, then real-time monitoring capability is achieved, but particle scattering and complex compound interference affect measurement accuracy
Solution Approach 1:
The patent changes the measurement parameter from total UV absorption to specific UV absorption at 254 nm. By measuring absorbance at this specific wavelength and applying the Beer-Lambert law with appropriate path length, the method achieves both real-time measurement capability and improved accuracy by selecting a wavelength where organic carbon has characteristic absorption
Solution Approach 2:
The patent introduces an optical path length parameter as an intermediary to resolve the contradiction. By using a defined path length (e.g., 10 mm cuvette) and measuring absorbance, the system converts the complex scattering problem into a manageable optical measurement that can be corrected using standard photometric principles
3Measurement precision
If fluorescence measurement is used for TOC determination, then high sensitivity is achieved, but the FDOM/TOC ratio varies with organic matter type and cannot be standardized
Solution Approach 1:
The patent uses homogeneous UV absorption measurement that responds to all organic carbon compounds in the same way at 254 nm. Unlike fluorescence which varies by compound type, the Beer-Lambert law applies uniformly to all absorbing species, allowing standardization across different water types and organic matter compositions
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 accurate, real-time TOC measurements with improved signal-to-noise ratio and reduced interference, capable of detecting TOC levels comparable to conventional laboratory methods, while minimizing environmental impact and operator expertise.
Implementation Method 1
illuminating the aqueous stream with electromagnetic radiation at a wavelength of 254 nm
Implementation Method 2
measuring an intensity of the electromagnetic radiation transmitted through the illuminated aqueous stream
Data Source
AI summary
A method and apparatus for the measurement of total organic carbon content in an aqueous stream is disclosed. Absorbance of electromagnetic energy by the aqueous stream is measured in an optical sample cell with pulsed light at a wavelength of 190 nm±10 nm. A value of total organic carbon from the measured absorbance is calculated without absorbance or fluorescence measurement at any other wavelength.