Related Experiment Video
Updated: Jan 30, 2026
07:58
A Polyaniline-based Sensor of Nucleic Acids
Published on: November 1, 2016
8.4K
Visual and Precise Detection of pH Values under Extreme Acidic and Strong Basic Environments by Cellulose-Based
Haq Nawaz1, Weiguo Tian1, Jinming Zhang1
1CAS Key Laboratory of Engineering Plastics, CAS Research/Education Center for Excellence in Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences (CAS) , Beijing 100190 , China.
Analytical Chemistry
|January 17, 2019
Summary
A novel cellulose-based sensor, Phen-MDI-CA, offers instrument-free pH determination in extreme conditions. This advanced pH sensor provides precise visual and fluorescent readings for industrial and environmental applications.
Area of Science:
- Materials Science
- Analytical Chemistry
- Chemical Sensing
Background:
- Accurate pH determination is crucial for industrial processes, life sciences, and environmental monitoring.
- Instrument-free pH sensing, especially in extreme acidic and basic conditions, remains a significant challenge.
- Existing methods often lack precision or require specialized equipment, limiting their practical application.
Purpose of the Study:
- To develop a novel, instrument-free pH sensor capable of precise determination in extreme acidic and basic environments.
- To utilize the intramolecular charge transfer process for a highly sensitive and visually responsive pH sensor.
- To fabricate the sensor into a practical format, such as test strips, for widespread use.
Main Methods:
- Synthesis of a cellulose-based sensor (Phen-MDI-CA) by combining a phenanthroline moiety and a urea group.
- Utilizing intramolecular charge transfer for pH-responsive colorimetric and fluorometric detection.
- Fabrication of the sensor into pH test strips via a coating method.
- Incorporation of pH-irresponsive dyes to create ratiometric sensing systems.
Main Results:
- Phen-MDI-CA precisely and visually determines pH values in extreme acidic (pH 1.0-2.0) and strong basic (pH 11.0-14.0) environments.
- Visible light mode allows naked-eye discrimination of specific pH values.
- Fluorescent mode achieves higher accuracy (0.2-0.4 pH interval) in the range of pH 11.6-13.2.
- Ratiometric systems demonstrate distinct color changes for precise pH interval detection.
Conclusions:
- The developed Phen-MDI-CA sensor offers a breakthrough in instrument-free pH monitoring under extreme conditions.
- This cellulose-based sensor provides a practical, visual, and accurate method for pH determination in diverse applications.
- This represents the first study to achieve precise, instrument-free pH monitoring in extreme acidity and strong basicity.
Related Concept Videos
02:28Titration Calculations: Strong Acid - Strong Base
33.8K
Calculating pH for Titration Solutions: Strong Acid/Strong Base
A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH. The pH at different volumes of added base solution can be calculated as follows:
(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the ionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then:
A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH. The pH at different volumes of added base solution can be calculated as follows:
(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the ionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then:
33.8K
03:22Strong Acid and Base Solutions
35.6K
A strong acid is a compound that dissociates completely in an aqueous solution and produces a concentration of hydronium ions equal to the initial concentration of acid. For example, 0.20 M hydrobromic acid will dissociate completely in water and produces 0.20 M of hydronium ions and 0.20 M of bromide ions.
35.6K
03:55Titration Calculations: Weak Acid - Strong Base
49.3K
Calculating pH for Titration Solutions: Weak Acid/Strong Base
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
49.3K
01:23Titration of a Strong Acid with a Strong Base
10.5K
During the titration of a strong acid with a strong base, pH calculations are primarily based on the concentration of residual hydronium or hydroxide ions. Initially, a strong acid like hydrochloric acid fully dissociates, creating hydronium and chloride ions, resulting in a low pH. The addition of a strong base like sodium hydroxide alters the concentration of hydronium ions by neutralizing them. As more base is added, the pH gradually increases. At the equivalence point, all hydronium ions...
10.5K
01:22Absolute and Local Extreme Values
73
The highest and lowest values of a function, relative to a reference axis, are known as extreme values. These include absolute maximum and absolute minimum values, which represent the highest and lowest points the function reaches across its entire domain. Within a restricted portion of the function, the highest and lowest values are referred to as local maximum and local minimum values, respectively.Periodic functions, such as sine and cosine, show extreme values at infinitely many points due...
73
01:20Titration of a Weak Base with a Strong Acid
8.9K
The titration curve of a weak base like ammonia with a strong acid like hydrochloric acid is the mirror image of the titration curve of a weak acid with a strong base.
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...
8.9K