Nitric Acid and Acetone Waste in a Corroded Lab Cabinet
A university research lab has a corroded steel cabinet containing a 4 L HDPE bottle of 68% nitric acid sitting in a polypropylene tray with a 2 L bottle of acetone waste. The tray is cracked and contains a small amount of yellow-brown liquid. At 09:10 the fume hood airflow alarm sounds; the measured face velocity is 0.3 m/s against a 0.5 m/s standard. Two occupants report throat irritation and a headache. The lab has a spill kit with sodium bicarbonate, vermiculite, and nitrile gloves, but no acid-resistant suit. The building has 40 occupants; the lab door is open to the corridor. The safety officer is 20 minutes away. The lab manager wants to neutralize the liquid with bicarbonate immediately.
1. What should be done first, and how should the occupants be managed?
Read the worked answer
Reasoning: The combination of a nitric acid bottle, acetone waste, a cracked tray, yellow-brown liquid, and a fume hood failure suggests possible acid vapor, nitrogen oxide formation, and a flammable/oxidizer interaction. The immediate threat is inhalation and eye exposure, not the condition of the cabinet.
First actions: stop work, evacuate the lab, close the lab door, and activate the building alarm if the odor or symptoms are spreading. Move the two symptomatic occupants to fresh air and arrange medical evaluation; do not let them return to collect belongings. Post a warning sign and prevent entry. Notify the safety officer, the principal investigator, and facilities. Do not attempt cleanup while the hood is degraded and the liquid's composition is unknown. If the corridor is affected, consider evacuating the floor. The lab manager should not neutralize anything at this stage: neutralization can generate heat, spatter, and gases, and the yellow-brown liquid may contain nitrogen oxides that require respiratory protection.
2. Evaluate the proposed neutralization and specify a safer cleanup approach.
Read the worked answer
Reasoning: Bicarbonate neutralization is not automatically safe for a strong oxidizer mixed with an organic solvent. The acid can oxidize the acetone or its degradation products, and adding bicarbonate to a confined, cracked tray can cause foaming, heat, and aerosol release. The yellow-brown color may indicate nitrogen oxides, which are toxic and require SCBA-level protection.
Safer approach: keep the area isolated until a trained hazmat team assesses compatibility. If the material is confirmed as a small, compatible acid residue, neutralize slowly with a compatible base such as soda ash or lime, in a ventilated area, with acid-resistant gloves, goggles, face shield, and apron; add the base slowly and control foaming. Otherwise, absorb with vermiculite or acid-rated pads, avoid organic absorbents and metal containers, and place the waste in a compatible, labeled container. Do not use paper towels or wood. Clean the cabinet with an acid-resistant detergent, then dispose of the cleaning materials as hazardous waste. The cracked tray and corroded cabinet should be replaced, not reused.
3. What root causes and corrective actions should be documented?
Read the worked answer
Reasoning: The incident is not only a spill; it is a storage-segregation and engineering-control failure. Documenting only the cleanup would leave the same conditions in place.
Root causes: nitric acid stored with organic waste; incompatible secondary containment that cracked; steel cabinet corroding under acid exposure; hood face velocity below the 0.5 m/s standard; no routine inspection of the tray or cabinet; a culture that allowed immediate neutralization without hazard review.
Corrective actions: segregate acids from organic solvents and waste; use polypropylene or other acid-compatible secondary containment; replace the cabinet with a corrosion-resistant unit; repair the hood and verify face velocity before the lab reopens; update the chemical hygiene plan and waste-segregation labels; train lab users on acid/oxidizer hazards and spill response; add a spill drill and inspection log; document medical follow-up and the incident investigation. Verify local requirements for reporting the exposure and the chemical release.