Arduino pH Sensor Module

This pH sensor module can measure a pH range from 0 to 14. The theoretical measurement is based on the concentration of hydrogen ions. It provides highly accurate real-time pH measurements and is compatible with most pH measuring devices with a BNC connector. The cable length is 75cm, and the sensor has a cylindrical structure.

The pH Sensor Module is designed to measure water quality and is fully compatible with Arduino boards.

Features:

• pH measurement range: 0 to 14 PH
• BNC connector, suitable for most pH meters and controllers with a BNC connector
• Suitable for a wide range of applications: aquariums, hydroponics, laboratories, etc.
• Zero point: 7 PH ±0.5 (25°C)
• Alkali error: 0.2 PH ≤15mV
• Theoretical slope: ≥ 97% (25°C)
• Internal resistance: ≤ 250MΩ (25°C)
• Response time: ≤ 1 minute
• Operating temperature: 0°C to 60°C
• Connection type: BNC
• Adjustable gain with potentiometer
• Probe length: 17cm
• Cable length: approx. 75cm
• Weight: 50g (100g)

Package Contents:

• 1 x pH Electrode Probe
• 1 x Measurement Module
• Connection Parts

Preparation Before Use:

1. Slowly remove the protective bottle from the electrode and set it aside for later use.
2. Use deionized water to clean the white sedimentary salt on the outside of the electrode.
3. To maintain an appropriate penetration rate, the liquid level in the tube should immerse the tip of the spiral glass tube and exceed the sample liquid level by at least 1 inch (2.5cm). When in use, completely immerse the electrode bulb in the measured liquid. Allow the bulb to fully contact the test liquid for ionic reaction.
4. Gently shake the electrode (like a clinical thermometer) to remove air bubbles from the electrode.
5. Soak the electrode in pH electrode storage solution for 1 hour. If storage solution is not available, add 1g KCl to 200mL pH7 buffer as a temporary storage solution. When not in use, store the bulb tip in a long-term protection solution to activate and protect it. The preparation method is to add 10mL 3.3kCl solution to 200mL pH4 buffer solution. [3.3KCL is saturated potassium chloride; the configuration method is 23 grams of potassium chloride and 100ml deionized water.]

Using Electrodes - Points to Note:

1. Use fresh buffer solution.
2. Open the electrode protective cap.
3. Measure the gap and rinse the electrode with deionized water.
4. Stir the buffer and sample: a) always stir at the same speed; b) stir first, then measure.
5. When preparing the pH electrode, rinse the electrode with distilled water before and after measurement. Use a lint-free cloth to absorb excess water from the electrode tip to avoid static electricity, which can interfere with accurate pH measurement.
6. Ensure the buffer temperature is the same as the sample. If the sample temperature differs, use a temperature compensation probe for correction.
7. Periodically check the electrode slope using a two-point calibration method. If the electrode reading drops or the slope is below 92%, clean the electrode as described in the electrode cleaning section.

Electrode Maintenance:

1. Cleaning the Electrode:

General cleaning solution: Soak the electrode in 0.1M HCl or 0.1M HNO3 solution for 15 minutes, then soak the electrode in electrode storage solution for 30 minutes.

2. Removing Blocked Liquid Junction (Salt Precipitation):

Causes: Hard water, sludge, organic contaminants, plankton microorganisms, algae, etc. Adhere to the water-permeable sand core around the bulb and PTFE, causing the external reference electrode to function improperly.

Solution: Soak the electrode in warm water (60°C) for 15-20 minutes; soak the electrode in warm saturated KCl (60°C) solution for 20-30 minutes and cool to room temperature; soak the electrode in pH 4 buffer solution for 20-30 minutes. Check for excessive crystals, and if present, repeatedly rinse with deionized water to check normal flow.

3. Removing Inorganic Matter Deposition on pH-sensitive Membrane:

Causes: Measurement of inorganic samples.

Solution: Clean with EDTA, ammonia, or acid.

4. Dehydration of pH-sensitive Membrane:

Causes: Improper storage, long-term use, operation at high temperatures, or strong alkaline solutions, resulting in slow and unstable response.

Solution: Activate the electrode by soaking it in 0.1M HCl for 1 minute, rinse with tap water for 30 seconds, soak in 0.1M KOH for 1 minute, rinse with tap water for 30 seconds, calibrate with buffer solution. If it still doesn't work, repeat the steps up to 3 times.

5. Long-term Electrode Use and Maintenance:

Solution: After 2-3 months of use, perform bulb cleaning and check the liquid junction for blockages. Remove the electrode from the environment and inspect for any dirt on the bulb surface. If any dirt is present, wipe with ethanol cotton and clean with deionized water. [Note: The bulb is fragile, handle with care during cleaning.] Check the liquid junction for any contaminants, rinse with deionized water or shake the electrode back and forth in the measurement container. If the water is not clean, replace it until the contaminants disappear. Then rinse the electrode and place it in an activation solution for 8 hours, followed by standard solution measurement to restore measurement condition.