I am working with electrocoagulation for As removal using the current of 1.5A(J=18.5mA/cm2) 7V. pH of water 6.8. Am getting high amount of bubbles at the surface which obvious will reduce treatment efficiency. I have applied the same operational parameters on fluoride without bubbles/foams formation. How to minimize this effect? Any suggestion
There's a great paper that my colleague Mark F. Sonnenschein directed me to a few years back: Article Mechanisms of Foam Destruction by Oil-Based Antifoams
It gets into the details of how certain chemicals can act as either antifoams or defoamers to destabilize foam bubbles.To try to explain using an example my home life: Consider boiling pasta in water. If your pot is small and it's filled with water, and then pasta is thrown into the boiling water, there will be foaming. Close the lid and the boil over will be even worse. The way to prevent the boil over is often to add for example vegetable oil or olive oil into the water (just a teaspoonful or less should be enough). This is enough to destabilize the bubbles so that they pop before the foam can boil over.
Long story short, I would suggest using some sort of high boiling oil (so that you don't get flash fire, since you're using electric charge.... Don't use volatile oils!), maybe vegetable oil, in very small quantity, and see if that limits the foaming. Please let me know how it works!
Thanks Kaoru
I rainsed the electrodes using sodium hydroxide and sulfuric acid 1M and then in distilled water. I also added the NaCL to 2g/L from 1g/L previously used, Now I see no more formation of foams. It seems there was formation of passive layer on the surface of electrodes which i will try to know why....
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