Graphene cannot be cleaned since it is only a few atoms thick. On top of the problem with nano particles, they are cancerous due to ther tiny size.
Let us bring back asbestos and lead amd mercury.
A cheap means of desalinating seawater would be a simply tremendous invention. On a large enough scale it could be used to meet immediate human needs and even to green swathes of the world’s deserts.
That said, I’ve been hearing a lot of cheerleading for Graphene for years. Thus far there hasn’t been much to show that it really is some kind of wonder material.