Is this a Single Member LLC that has NOT made an election to be taxed as a corporation?
If so, it is a "disregarded" entity for income tax purposes. In other words, the LLC is ignored and things are treated as if everything was done by you in your personal name. So it effectively is a personal loan (at least for income tax purposes).
As Critter pointed out, unless this is a business that is in the business of lending money, the interest you receive is treated as any other interest that you receive (such as from your personal bank account).
The money that you put into the LLC bank account has no bearing on anything. It is just moving money from one of your bank accounts to another. Doing that could help preserve the legal protection that the LLC may give, but has no effect for income tax purposes.
