Tag: chemicals-reactive

Related specifically to reactive chemicals (including water-reactives; air-reactive/pyrophoric compounds are under chemicals-flammable)

Got nanomaterials?

Nanomaterials pose challenging health & safety issues, because the toxicity and other biological effects of many nanomaterials are unknown. It is entirely possible that nanomaterials can be much more dangerous than the base materials. For example, a lump of coal or a diamond is relatively nonhazardous, but carbon nanotubes have long been suspected of asbestos-like action on the lungs, leading to lung and pleural lining cancers. [https://blogs.cdc.gov/niosh-science-blog/2008/05/20/nano/]

The Centers for Disease Control and Prevention’s National Institute of Occupational Safety and Health recently issued four documents describing best practices for working with nanomaterials, including [items from CDC press release cited below]

• Handling and weighing of nanomaterials when scooping, pouring, and dumping;
• Harvesting nanomaterials and cleaning out reactors after materials are produced;
• Processing of nanomaterials after production;
• Working with nanomaterials of different forms, including dry powders or liquids.

The last item, working with nanomaterials, comes in a poster format suitable for hanging in the lab; the others are guidance documents.

It is strongly advised that researchers and principal investigators working with nanomaterials familiarize themselves with these documents, since they represent known best health & safety practice for their work.

The documents may be found on the CDC website at https://www.cdc.gov/niosh/updates/upd-03-12-18.html

Warning: Graphite oxide explosions

Graphite oxide (GO; also known as graphene oxide) is an intermediate compound used in its own right and as a route to graphene. Several papers over the last few years have indicated that bulk GO, when heated, can explode; samples of a few milligrams created energy releases that damaged laboratory equipment. (Qiu, Y., et.al. Explosive thermal reduction of graphene-oxide based materials: Mechanism and safety implications. Carbon 72, 2014, pp215-223. Doi: https://doi.org/10.1016/j.carbon.2014.02.005)

Self-heating is also possible, particularly with addition of dopants such as hydroxyl ions (-OH), which drop the temperature for thermal runaway by as much as 50˚C. Such a reduction can overlap with common processing temperatures for GO.

Results presented at the recent American Chemical Society meeting in New Orleans (Green, M.J., et.al. Study of safer storage of graphene oxide. Paper number CHAS 3.) indicate that the temperature at which thermal runaway/explosion occurs drops as the amount of material increases due to mass and thermal transfer effects.

Storage of substantial quantities of GO therefore may pose both a laboratory and a process hazard. It is recommended that researchers working with this material minimize storage, perform a thorough literature search before heating GO, and take appropriate precautions to protect against mishaps.

Warning: Azidophenylalanine

The unnatural amino acid azidophenylalanine is used for modifying and labeling proteins in biological and biochemical research. The azido group, though, is often a bad actor, leading to “energetic events,” (i.e., explosions).

A recent article in J. Org. Chem. (doi:10.1021/acs.joc.8b00270) by Mark Richardson, Gregory Weiss, and other University of California researchers describes an inexpensive synthesis of this amino acid. In the course of the research, the researchers studied the intermediates and final product using differential scanning calorimetry and discovered that azidophenylalanine “behaved like an explosive compound,” an unexpected result. The authors recommend that crystalline samples of azidophenylalanine not be stored for long periods and that all stocks of the material be kept in dilute aqueous solution.

Further details can be found in a Safety Note in Chemical & Engineering News.

Protect your face with a face shield

When a hazard involves a lot of energy or aggressive chemicals, your face may be at risk as well as your eyes. Also, Z87.1 or Z81+ rated eye protection may not be adequate to protect your eyes, so additional protection might be prudent. If you could injure your face in an accident, use a face shield to protect your face – learn more in High energy facial protection.

Protect your eyes from chemical hazards

Chemical hazards require eye protection specifically designed for chemical hazards. Many chemicals can cause serious damage or irritation when they get into your eyes. These include, but are not limited to, acids, caustics and solvents. When working with chemical eye hazards, wear chemical splash goggles to protect your eyes – learn more in Chemical Hazard Eye Protection.

Incident report: Unexpected pressure relief, UTL, Apr 2014

A pair of undergraduates in a chemistry class loaded a pressure vessel (a “Parr bomb”) with reactants and placed the vessel in a furnace, leaving the reaction to run for the night.

Several hours later, during an evening class in the same lab, an unanticipated reaction occurred in the vessel. This raised the pressure beyond the established safe operating limit for the experiment and burst the vessel’s safety rupture disc. The class heard a loud bang followed by a strong odor described as “microwaved broccoli.”

The instructor evacuated the lab. Because procedures were not clear, a delay followed before anyone contacted Security and Health, Safety & Environment. Once the authorities were notified, the laboratory was inspected for damage, and ventilation was increased to remove the odor (which had spread throughout the floor).

Learn more about this incident in Incident pressure relief UTL Apr2014.

Incident report: Regulator overpressure, Ames Hall, Feb 2014

A researcher was attempting to change the acetylene pressure on an atomic absorption spectrometer by adjusting the pressure regulator. He inadvertently set the pressure well above 15psig, despite the signs (and the red markings on the regulator) warning not to do so. When acetylene pressure exceeds 15psi, the gas can liquefy; in this state, acetylene can suddenly and explosively polymerize. Fortunately, this did not occur, although the regulator was ruined from overpressurization.

Learn more about this incident and its implications in Incident Ames Feb2014.