Good lord! Where, oh where should I begin on this one?....

As already mentioned, dilute Muriatic acid (HCl) will remove oxidized metal from iron parts (acetic acid is safer, but slower). It can also strip out certain metals in alloys, so that is one thing that needs to be mentioned. The hydrogen brittling effect is most prevelent in nickel containing materials, as you can form nickel hydrides, which are flammable. If the acid solution only contains the acid, it can be neutralized by the appropriate amount of a base to give a salt solution and water. This process can generate a lot of heat (exothermic). If the salt is non-toxic, then the dilute salt solution can be released into the environment if the laws allow for that type of disposal. If any toxic material is possibly present in the solution, then it must be handled as containing a toxic material. Oil and grease can cause enviornmental problems, so they must be disposed of properly and not just dumped into the ground. Used motor oil is different chemically than crude oil from the ground. There are carcinogens in used motor oil from heated hydrocarbon contact with metal surfaces inside of engines. One must always follow proper procedures when working with corrosive chemicals, including goggles, gloves, protective apron or suit to name a few. Acid baths must always have a spill zone around them to contain spills should they leak out. Never, ever put water into a concentrated acid container! The resulting exothermic reaction can spray out of the container and hit you (not to mention the vapors). This is just for starters. The list can go on and on for several more pages...


My thanks to those who responded prevously on this topic with appropriate chemical answers....


Don't get me started on cadmium, mercury or lead in the above discussion. My PhD was in developing sensors to environmentally detect those metals....