The ‘extremely flammable’ chemical behind the fire in the flooded Texas plant – Washington Post

Two explosions were reported on Aug. 31 at the flood-hit Arkema plant in Crosby, Tex. (Reuters)

Early Thursday, while Texas wrestled with Hurricane Harvey's aftermath, a powerful reaction belched fireandblack smoke from a chemical factory in Crosby, Tex., 30 miles northeast of Houston.The factory, operated by French chemical company Arkema, lost power in the flood. The refrigeration system used to cool tractor-trailer tankers full of chemicalsfailed.So did the backup generators. There was a popping noise, officials said. Then awarmtanker, full ofliquidorganic peroxides, erupted into flames.

Organic peroxides are extremely flammable, noted the company in a statementon its website Thursday. Arkema said it expected more fires to start and planned to allow the chemicals to burn themselves out.

They're actually very marvelous, said chemistWilliam Carroll,an adjunct professor of chemistry at Indiana University who has worked with organic peroxides for many years. You use them in a way that they fall apart and do so at very specific temperatures. Oneorganic peroxide can be tailored to break up at 30 degrees Celsius [86 degrees Fahrenheit], while another will do so at 40 degrees. The trick is to keep them safely below those temperatures sometimes frozen solid, or, in the case of the Arkema plant, stored as chilled liquids.

When peroxides heat up, they react. Thursday, around 2 a.m. local time, the materials did exactly what they're supposed to do, Carroll said. They decomposed.

A peroxide compound contains two linked oxygen atoms. The peroxide you're perhaps most familiar with, hydrogen peroxide, is a chainof two oxygen atomscapped on both ends with a hydrogen atom. Peroxides are useful because the chemical bond between the oxygen atoms is so unstable. Oxygengreedily snatches electrons from other atoms. Thisrapaciousness makes oxygen a flighty partner when bonded to itself.

Michelle Francl, a chemistry professor at Bryn Mawr, has an antique glass container labeled peroxide in her office. A laboratory safety officer who caught sight of the jaralmost bolted until Francl gave her assurances that it was scrubbed clean. Had it contained dry peroxide, she said, the jar could havecombusted at a jolt.

Peroxides arebasically tiny little molecular canisters of oxygen, Francl said. Theyre designed to break apart and be highly reactive. Its like having a whole bunch of fragile glass molecules.People have used hydrogen peroxide's fizzy instability tobleach hair, disinfect wounds not always arecommendedtechnique and, at high concentrations, propel rockets.

Organic peroxides substitute the hydrogen caps for clusters of carbon plus other elements.There are many kinds of organic peroxides, with almost as many uses. Benzoyl peroxide, as an acnemedication, tears apart proteins inskin bacteria. Arkema advertises a wide range of peroxide products: not just to defeat zitsbut also to kick-startpolymer reactions, to improve the color of resins, to create plastics for pipes and countertops.

Your plastic kitchen countertop, of course, isn't in danger of spontaneous combustion. When manufacturing plastics, the reactive peroxide is aspark, not a building block. Once the peroxide kicks off thea chain reaction,the resulting moleculesbraid together in astable polymer. The beauty of peroxides is their ability to keep the reaction going, churning out free radicals. Every time a radical touches something it turns it into a radical, Francl said. Its like zombies.

It's no coincidence that Texas isthick with chemicalplants, situated alongside natural gas and oil refineries. Where there are fossil fuels there are carbon byproducts, a key component of organic peroxides. Youmight hear oil and think of fuel. But chemists think of lots of little carbon frameworks. Like Lego, Francl said.

And the choice to construct the chemical plant in a rural area was no accident, either, Carroll said. You won't find such a factory in downtown Houston. They're acutely aware that they're working with a reactive material, he said, that has to be handled in a certain way.

The Arkema plant is far from the first to have an accident with organic peroxides. Between 1980 and 2001, there were about a dozen accidents severe enough to trigger reviews from the U.S. Chemical Safety Board, Francl noted, including a previous event in Crosby in 1998. A handful took place in Pasadena and other nearby Texas cities.

On Thursday, a deputy with the Harris County Sheriffs Office sought treatment for inhaling fumes, The Washington Post reported. Other organic peroxide accidents have resulted in injuries. In 2008, in Edmonton, Alberta, nine people were hospitalizedafter a peroxide holding tank caught fire. (Terrorists have put organic peroxides to the most horrific use. Bombingattacksin Manchester, London, Paris and Brusselsinvolvedtriacetone triperoxide or TATP, a compound also known as mother of Satan.")

If there is a silver lining to the peroxide accident Thursday,thechemicals' reactivity means that they wont stick around in the environment. The chemicals will burn too quickly for floodwaters to sweep any of the liquid away. This is an acute event, not a chronic one, Carroll said.

What's left after such a chemical reaction? Smoke, but mostly carbon dioxide and more water.

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The 'extremely flammable' chemical behind the fire in the flooded Texas plant - Washington Post