Hey there, sofibels.
3.5" HDDs need external power, so if the adapter has it, I don't see a reason for you not to be able to use it. On the other hand if it uses power only from the USB ports, even if you are using a Y cable (for 2 USB ports) you won't be able to power up a 3.5" HDD.
Hope that helps.
Boogieman_WD