Is it permissible to count an uncollected loan as Zakat, especially if the original intention when giving it was Zakat?

Deeds are by intentions. So, whoever gives money to the poor or to any other deserving recipient of zakat, intending it as the obligatory zakat, then it is zakat. And whoever gives it intending it as a voluntary charity, then it is a voluntary charity. It is not permissible for him to count it later as part of his obligatory zakat, because he gave it with the intention of voluntary charity. Voluntary charity does not suffice for obligatory zakat, because zakat is an obligatory act of worship that requires intention for its performance. Therefore, if you pay your zakat to someone you know is deserving of it, with the intention of it being zakat, then it is valid zakat, and you are not required to inform the recipient that it is zakat.