Boron Removal via pH Adjustment and Feedback Control
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Solution Overview
Problem
Current methods for producing ultrapure water struggle to effectively remove boron, as boron behaves as a non-dissociated substance in water, making it difficult to achieve high sensitivity measurements and efficient removal, especially with reverse osmosis membrane treatment, and existing online boron monitors face challenges in accurately measuring low concentrations due to high noise levels.
Innovation Solution
The method involves subjecting permeated water to reverse osmosis membrane treatment followed by cation-removing treatment to increase the specific resistance of the water, allowing for high-sensitivity boron detection and regulation of treatment parameters such as pH, recovery rate, and supply pressure to control boron concentration, using a boron analyzer to measure and adjust these parameters for efficient boron removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reverse osmosis membrane treatment is used to remove boron, then most ion components and TOC can be removed, but boron removal efficiency is insufficient because boron behaves as a non-dissociated substance
Solution Approach 1:
The patent adjusts the pH parameter of the water to be treated to alkaline conditions (pH 9 or higher). This parameter change transforms boron from a non-dissociated substance into borate ions (B(OH)4−), which can be effectively removed by the reverse osmosis membrane. The pH adjustment is achieved by adding an alkali agent to the water before treatment.
2Reliability
If pH modifier is added to increase boron removal efficiency, then boron can be removed more effectively, but operation cost increases due to increased pH modifier consumption
Solution Approach 1:
The patent employs a feedback control system where a boron concentration measurement device continuously monitors the boron concentration in the permeated water. Based on this real-time measurement, the control device automatically adjusts the amount of alkali agent added to maintain optimal pH conditions. This feedback mechanism ensures efficient boron removal while minimizing pH modifier consumption by adding only the necessary amount.
3Ease of operation
If online boron monitor measures electrical conductivity to indicate boron concentration, then measurement can be performed, but measurement precision deteriorates at ppb levels due to high noise from high background signal
Solution Approach 1:
The patent changes the physical parameter of the water by adjusting pH to alkaline conditions, which transforms boron into borate ions. This parameter change enhances the electrical conductivity signal from boron, allowing online monitors to distinguish the boron signal from background noise more effectively and achieve accurate measurements at ppb concentration levels.
4Reliability
If pH of water to be treated is shifted to alkaline side to increase boron removal efficiency, then boron forms borate ions that can be removed by RO membrane, but pH modifier consumption increases
Solution Approach 1:
The system uses a feedback control mechanism where boron concentration in the permeated water is continuously measured and used to adjust the alkali agent dosage. The control device calculates the required pH modifier amount based on the measured boron concentration and maintains the pH at optimal levels for boron removal, thereby minimizing chemical consumption while ensuring effective treatment.
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 enables stable, efficient, and cost-effective boron removal in ultrapure water production, allowing for accurate measurement of boron concentrations at ppb levels, thereby improving the quality of water suitable for semiconductor and pharmaceutical applications.
Implementation Method 1
subjecting the water to be treated to reverse osmosis membrane treatment
Implementation Method 2
subjecting at least part of permeated water after the reverse osmosis membrane treatment to cation-removing treatment
Implementation Method 3
When inductively coupled plasma (ICP) emission spectrometry is used to measure boron at a low concentration level
Data Source
AI summary
A method of removing boron from water to be treated includes subjecting the water to be treated to reverse osmosis membrane treatment, subjecting at least part of permeated water after the reverse osmosis membrane treatment to cation-removing treatment, and measuring a concentration of boron in the resulting permeated water after the cation-removing treatment, in which a measured value for the concentration of boron is used to regulate at least one of: (a) the recovery rate of water to be treated in the above reverse osmosis membrane treatment, (b) the temperature of the water to be treated, (c) the pH of the water to be treated, (d) the supply pressure of the water to be treated, which pressure is applied to the reverse osmosis membrane during the reverse osmosis membrane treatment, and (e) when the reverse osmosis membrane used for the reverse osmosis membrane treatment should be changed.