Sciencemadness Discussion Board

An arduino controlled pH adjuster

Mixe - 4-6-2017 at 05:31

I'm building my first chlorate cell and I'm having issues with the pH adjustment. Beeing a perfectionist, the "top-it-with-a-little-HCl-every-now-and-then"- approach is not satisfying to me.

So I found this:

Arduino compatible pH sensor

The setup would be: the sensor connected to an Arduino Nano with code that reads it at regular intervals (possibly correcting for temperature also), compares it to a set value, and then doses HCl or NaOh accordingly through control of two solenoid valves.

The only thing I wonder about is how to get the electrode to survive beeing submerged into the hot, corrosive solution for longer periods of time.
Has anyone done anything like this?

[Edited on 2017-6-4 by Mixe]

[Edited on 2017-6-4 by Mixe]

unionised - 4-6-2017 at 07:56

The pH electrode is glass and will probably survive just fine.

You might need to switch off the electrolysis current for a short while when you take the measurements because that might otherwise upset the voltage from the pH electrode.

Melgar - 15-6-2017 at 04:08

In practice, pH sensing electrodes don't tend to last very long, and they have to be recalibrated frequently. I was in a research group a while back, that was studying the potential of using bound pH indicators on a polymer substrate, then measuring their color changes via optical sensors, and calculating pH from that.

byko3y - 15-6-2017 at 11:24

You should probably be looking for ph buffer rather than some explicit ph adjustment.

[Edited on 15-6-2017 by byko3y]

hyfalcon - 16-6-2017 at 07:53

You might want to read through this:

http://www.amateurpyro.com/forums/blog/2/entry-114-the-bucke...

unionised - 16-6-2017 at 09:42

Quote: Originally posted by Melgar  
In practice, pH sensing electrodes don't tend to last very long, and they have to be recalibrated frequently. I was in a research group a while back, that was studying the potential of using bound pH indicators on a polymer substrate, then measuring their color changes via optical sensors, and calculating pH from that.

In what amounts to a cell full of hot bleach, I'd bet on the glass electrode lasting longer. than dyed plastic.

Peristaltic pump

bandil64 - 22-6-2017 at 02:18

Quote: Originally posted by Mixe  
I'm building my first chlorate cell and I'm having issues with the pH adjustment. Beeing a perfectionist, the "top-it-with-a-little-HCl-every-now-and-then"- approach is not satisfying to me.

So I found this:

Arduino compatible pH sensor

The setup would be: the sensor connected to an Arduino Nano with code that reads it at regular intervals (possibly correcting for temperature also), compares it to a set value, and then doses HCl or NaOh accordingly through control of two solenoid valves.

The only thing I wonder about is how to get the electrode to survive beeing submerged into the hot, corrosive solution for longer periods of time.
Has anyone done anything like this?

[Edited on 2017-6-4 by Mixe]

[Edited on 2017-6-4 by Mixe]


I would definately use a peristaltic pump instead of a solenoid valve. You can control it using two PWM outputs from the Arduino and is much more precise than simply using a solenoid. If you pick them up from ebay they cost about the same aswell.

Let me know if you need some schematics for the interface circuit.

Regards
Bandil