Did you know buying a pre-loved kitchen knife from a resell site like eBay can save as much as 90 percent on energy costs needed to make a new knife? You can sanitize a used knife at home in seconds. If the knife does not have a plastic handle, place it in boiling water for 30 seconds. Turn off the heat and let the knife sit in the hot water and slowly pour the boiling water out; allow the knife to cool, and you're ready to go. If the knife has a plastic handle, fill a pot with the hottest water that comes out of the tap and let the knife soak for 15 seconds. Remove it with tongs and scrub with an old toothbrush to remove any debris.