You should use about one ounce of charcoal slurry every 4-5 hours not to exceed 2 days. It is a good idea to make about 4-5 ounces of powdered charcoal ahead to time to be carried with you while in survival mode.
The charcoal solution will taste bad and it will make you vomit. Try keeping the solution down long enough for it to absorb what ever is on your stomach causing the problems.
Activated Carbon is created by heating Charcoal to very high temperatures under oxidizing conditions. By very high I am talking 600-1200 degrees Celsius. This drives off all of the volatile compounds and leaves a lattice of carbon.
The pores created in this process are so small that they are able to attract and hold the organic molecules that try to pass through. This is done by Van der Walls force. Van der Walls is an attraction at the molecular or sub-molecular level.
In order for it occur the molecules must be in direct contact. This is possible because of the extraordinarily small size of the pore in the activated carbon. As an interesting side note this is the same force that allows a Gecko to walk up a pane of glass.
As for anyone saying that activated Charcoal is of no real use, you should ignore them, because they have no idea what they are talking about. On average granulated activated carbon contains so many pores that there are 500 square meters of surface area per gram.
Powdered activated carbon has even more. That translates into a very large capacity to capture and hold impurities.
The word activated in the name is sometimes replaced with active. Due to its high degree of micro-porosity, just 1 gram of activated carbon has a surface area in excess of 500 mm (about one tenth the size of a football field), as determined typically by nitrogen gas adsorption.
Sufficient activation for useful applications may come solely from the high surface area, though further chemical treatment often enhances the absorbing properties of the material. Activated carbon is usually derived from charcoal.
Remember that the wood used to make the charcoal can not be poisonous. The poison contained in the wood can make you ill or even kill you.
Stay Prepared! Stay Alive!