Is it possible, maybe in the future.. to make a working kidney of graphene, to clean the blood like a transplanted kidney...

Future is unknown: Your specific question about graphene is not one of current, heavy research but we never know about the future. However, we do have working artificial kidneys now - this is dialysis. Current technology uses artificial membranes to filter the blood, leaving the good stuff in and filtering out the bad stuff. But a transplanted kidney does this much better without hooking up to a machine.