What should be done to purify money that was obtained through a friend who works in online profit-making, and is it necessary to give away the principal and the profit as charity, or only the profit? And if it must be given away in Egyptian pounds, should it be at the current exchange rate or the exchange rate at the time it was acquired?

If you paid money to your friend under a valid Mudarabah (definition) (profit-sharing) contract for a permissible business and you made a profit, the original ruling is that the money is halal (definition) (permissible) and does not become haram (definition) (forbidden) merely due to doubt, for the fundamental principle concerning a Muslim is their soundness.

However, if the business was forbidden and resulted in illicit gains, then you are entitled to your principal. Any amount exceeding it should be spent on public welfare and charitable causes. The amount that must be disbursed is whatever exceeds your principal. This is calculated by taking the value of the dollars you received at the exchange rate on the day of receipt, then subtracting the principal paid, and disbursing the difference.