Safe Handling of Mineral Acids

1. Engineering Controls

1. Mineral acids should be handled in a chemical fume hood with the sash pulled down between the chest and what is being worked with in the hood. The height of the sash should be that which provides optimal safety while allowing one to execute tasks in an unencumbered manner.
2. Concentration of 3 M (M = molar) or less may be handled on a bench top, remembering that they are still corrosive.
3. Use secondary containers when possible.

2. Personal Protective Equipment (PPE)

1. Chemical splash goggles and/or a face shield must be worn if working outside a fume hood, or if the sash is not pulled down to the properly height due to experimental setup reasons.
2. When using hydrofluoric acid, use neoprene, or thick butyl rubber gloves. For other acids use double nitrile, neoprene, or PVC (vinyl) gloves. Replace gloves whenever a splash occurs.
3. Personnel should wear lab coats of similarly appropriate laboratory attire with chemical resistance to the acid(s) being used. Lab coats or aprons composed of rubber, neoprene, or polyvinylchloride (PVC) are appropriate. Cotton- or polyester-based lab coats readily absorbs liquids and are not recommended.
4. Protective clothing with long sleeves and full-length pants should be worn, along with closed-toed footwear.

3. Additional Precautions

1. Reactions with metals generate hydrogen gas, which may be flammable and potentially explosive.
2. Do not mix nitric acid with organics, which may cause an explosion or fire.
3. Skin contact with hydrofluoric acid leads to chemical burns, severe tissue damage, and can even lead to bone dissolution if not treated immediately. In the case of hydrofluoric acid coming into contact with skin or tissue, flush contact area with tepid water for 5 min, apply calcium gluconate to counter the effects, and then seek medical attention. The onset of effect(s) from hydrofluoric acid can be delayed by as much as 8 h. It is especially important to seek medical attention for any HF burn because of these delayed effects. HF essentially dissolves your bone structure, therefore it should be handled with great care.

4. Storage

1. Mineral acid containers should be stored in an approved corrosive (acid) cabinet. This cabinet should be clearly labeled as containing acids. Acid amounts of less than 1 L should be stored at any one time.
2. Mineral acids are chemically incompatible with bases, oxidizing agents, organic materials, and combustibles, and should be stored separately. Proper storage practices are for separating acids from other acids stored within the same cabinet using secondary containment. The secondary container should be constructed of polyethylene, PYREX, or Nalgene.
3. Strong mineral acids should not be stored in the same cabinet.
4. Avoid storing acids on metal shelves, or use secondary containers made of plastic or in case of hydrofluoric acid, polyethylene.
5. If mineral acids must be transferred to smaller working containers, make sure the container is compatible with the acid and labeled with all of the required information that is on the permanent or manufacturers' container labels. The permanent or manufacturers' container label must meet OSHA's Hazard Communication standard [29 CFR 1910.1200(f)(1)] by providing the following information:
   • Chemical identity and appropriate hazard warnings.
   • Hazard warnings must provide immediate recognition of the primary health and/or physical hazard(s) using pictograms, signal words, and precautionary statements. The hazard label must also be permanent, legible, and written in English.
   • The name, address, and telephone number of the chemical manufacturer, importer, or other responsible party.
6. Acid inventories should only be as large as what can safely be stored in the laboratory.
7. Always handle mineral acids in a properly functioning chemical fume hood. Ensure that the sash is working properly, exhaust management is appropriate, and recently verified. Additionally, practice good housekeeping in the hood prior to utilizing the mineral acid. Remove incompatible materials and ensure clutter in the hood is reduced or eliminated to a level that enables safe handling and manipulation.
8. Containers should be kept upright and closed at all times, and stored in a dry, well-ventilated location, ideally in a corrosive (acid) cabinet. When opened, containers must be resealed to prevent spills.
9. Store and handle away from ignition sources and avoid heat and shock or friction.

5. Emergency Procedures

1. Exposures/Unintended Contact
   1. In case of skin contact, immediately remove contaminated clothing and rinse the affected body part thoroughly with water for at least 15 min.
   2. In case of acid exposure to the eyes, immediately rinse eyes with a significant quantity of water for a minimum of 15 min, and then promptly seek medical attention.
   3. In the case of large amounts of vapor inhalation, move the affected person to fresh air, then contact the appropriate medical personnel.
   4. In the case of ingestion, immediately seek medical attention.
2. Spills
   1. In the case of a chemical spill, the sooner it is controlled, the less damage it can cause. As the spill is controlled, the spill should also be contained in an as small as possible area and prevented from spreading further.
   2. The spill must be cleaned immediately. Laboratories requiring the handling of mineral acids should have spill kits readily available.
   3. Decontamination or neutralization may be required, for which solid sodium bicarbonate or calcium carbonate is recommended. The spill may be covered with the acid neutralizer and then swept up with absorbent pads or a broom. If this is to be handled by a laboratory investigator, consultation as to the appropriate level of PPE is recommended. A standard operating procedure (SOP) should be developed to handle these kind of safety issues in the laboratory prior to any experimental work requiring mineral acid usage.
   4. In case of a large spill, evacuate the area immediately alerting others, and call 911. Make sure someone is near the scene to provide information to the responders. Have the product information and the safety data sheet (SDS) available.
   5. All spills, minor or large, must be reported to the proper regulatory agencies. Environmental Health and Safety (EHS) performs all regulatory notifications and verifies that the spill clean-up meets regulatory requirements and standards.

6. Waste Disposal

1. Acid wastes should be kept separate from other waste materials and used with secondary containers.
2. Check waste solutions periodically for gas evolution and avoid over-pressurized containers, which may violently erupt.
3. Dispose of waste through your organization's chemical waste management system.
4. If the waste solution does not contain any hazardous metals, elementary neutralization may be considered. The acid waste may be poured into a large quantity of ice (500 g of ice per 100 mL of acid) and neutralized with an aqueous basic solution, such as 1 M or 10% sodium hydroxide (NaOH) or saturated sodium bicarbonate (NaHCO₃) in water until the pH is neutral. The neutralized solution may then be poured down the drain.
5. If the waste solution contains any hazardous metals such as gold, platinum, lead, or chromium, the solution should be labeled and disposed of through the chemical waste management system.