UV-Activated Persulfate Process for Semiconductor Water TOC Reduction
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Solution Overview
Problem
Current methods for producing ultrapure water in semiconductor manufacturing lack a reliable, continuous source of low Total Organic Carbon (TOC) and are inefficient in purifying spent water for reuse, as they often require pH adjustment, high temperatures, and batch processes.
Innovation Solution
A UV-activated persulfate process that decomposes organic compounds by converting persulfate into sulfate radicals at ambient temperature, using a photochemical reactor system, either continuous-stirred tank or plug flow, to reduce TOC in water streams before discharge or reuse, with persulfate addition upstream of an ultraviolet light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pH adjustment and high temperature heating are used to reduce TOC in water, then TOC removal effectiveness is improved, but process complexity and energy consumption increase
Solution Approach 1:
The patent extracts and eliminates the need for pH adjustment and high temperature heating steps from the TOC removal process. By using UV-activated persulfate oxidation at ambient temperature and neutral pH, the method removes these complex process steps while maintaining effective TOC reduction, directly resolving the contradiction between removal effectiveness and process complexity
Solution Approach 2:
The patent changes the operating parameters from requiring pH adjustment and high temperature (110-170°C) to operating at ambient temperature and neutral pH. This parameter change enables simplified continuous processing while achieving the same or better TOC removal effectiveness, resolving the technical contradiction
2Manufacturing precision
If batch processing with pH adjustment and high temperature heating is used, then TOC reduction is achieved, but continuous production capability and efficiency are reduced
Solution Approach 1:
The patent implements a continuous flow reactor system where water continuously passes through the UV-activated persulfate oxidation zone. This continuous processing mode eliminates the batch-to-batch interruptions and enables sustained high-volume TOC reduction, directly resolving the contradiction between TOC reduction effectiveness and continuous production capability
Solution Approach 2:
The patent incorporates a pre-mixing zone where persulfate is预先 mixed with the water stream before UV irradiation. This preliminary action ensures optimal reaction conditions are established before the main oxidation zone, enabling efficient continuous processing without compromising TOC reduction effectiveness
3Manufacturing precision
If extreme dose UV irradiation with heating is used to activate persulfate, then TOC oxidation is improved, but energy consumption increases
Solution Approach 1:
The patent changes the activation method from extreme dose UV with heating to moderate dose UV at ambient temperature. By using persulfate's natural absorption at 254 nm UV wavelength, the system achieves effective radical generation and TOC oxidation without the excessive energy input required by conventional methods, resolving the contradiction between oxidation effectiveness and energy consumption
Solution Approach 2:
The patent replaces the thermal heating mechanism with a photochemical activation mechanism. Instead of using heat to activate persulfate (thermal energy), the system uses UV light absorption (photochemical energy) to generate sulfate radicals, which is more energy-efficient and achieves the same oxidation effect with lower energy consumption
4Manufacturing precision
If multiple process steps including pH adjustment and heating are used, then TOC removal is effective, but cost-effectiveness is reduced
Solution Approach 1:
The patent extracts and eliminates the need for pH adjustment chemicals, heating energy, and complex process control systems. By using UV-activated persulfate at ambient temperature and neutral pH, the method removes these cost-intensive elements while maintaining effective TOC removal, directly resolving the contradiction between removal effectiveness and cost-effectiveness
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 process effectively reduces TOC to low levels (<5 ppb) in both pure and spent water, enabling continuous production of ultrapure water and allowing for the reuse of treated water, while being cost-effective and efficient by optimizing reactor design and UV light utilization.
Implementation Method 1
The ultraviolet light is absorbed by the persulfate—converting the persulfate into sulfate radicals
Implementation Method 2
The sulfate radicals oxidize TOC, converting the contributing compounds into CO2 and mineral salts
Data Source
AI summary
In a system for decomposing organic compounds in water for use in semiconductor manufacturing, a chemical reactor vessel having a fluid inlet and a fluid outlet, a persulfate anion addition system upstream of the reactor vessel, and a light emitting device contained within the reactor vessel. The light emitting device provides light capable of decomposing persulfate anions.