Hi guys,

 

Thanks for reading this topic! I would like to ask for some advice on what happens with activated carbon filters, or why you think this is. I was doing an experiment, using an activated carbon filter - Brita Water Filter (for drinking purposes), and running contaminated lake water through it. I tested the pH of the water after, and it was basic - a reading of 6.0, compared to the 7.5 of the lake water before. Why is this? Thank you!

Ah sorry, I meant acidic

The activated charcoal could be removing some of the proteins from the water. These could be buffering the water to some extent and dropping the pH. 'Pure' water tends to have a slightly low pH because of dissolved CO2.

 

You have given me an idea, I want to remove proteins from my koi pond, they are causing foam on the surface. Brita water filters may be the answer.

It's likely that some of the carbon at the "edges" of the graphite molecules is present as carboxylic acid or phenol groups which are acidic.

Just had a look at the Brita web site. They say that their filters will remove some of the salts that cause hard water, i.e. they have some ion exchange capacity. Taking out calcium carbonate would certainly drop the pH.

Looks as though they are doing what they are supposed to do.

The most famous reaction of activated carbon is to anything, is a diamond. Diamonds are the result of carbon reacting with air - pressure and heat, above extended periods of time. Once carbon reacts with water under pressure, water gas is formed.

Heat and pressure, yes, but I'm pretty sure there is no 'reacting with air' in the formation of a diamond. It is pure carbon.