Tag Archives: sulphur

The Wreck.

Novel nanocomposite material might prevent shipwrecks from rotting

Shipwrecks are coming — soon, to a museum near you. And it’s all thanks to nanotechnology.

The Wreck.

“The Wreck”, Knud-Andreassen Baade.
Image via Wikimedia.

A novel approach hopes to turn the damp, pitted wood of ancient shipwrecks into a showstopper. The team is currently using ‘smart’ nanocomposites to conserve the 16th-century British warship, the Mary Rose, and its artifacts. Should the process prove effective, museums will be able to display salvaged wrecks in all their glory without them rotting away.

The old that is strong does not wither

Thousands of shipwrecks have come to rest on ocean floors through the centuries. These drowned leviathans spark the passion of both researchers — who can learn a lot about past battles and ways of life from the wrecks — and public alike.

However, it’s very risky to go in and try to recover shipwrecks. Metal ships tend to weather the years underwater with some grace, but the wooden ones quickly rot away — after roughly a century, the only parts that remain are those that were buried in silt or sand soon after the sinking. Even worse, these timber skeletons quickly deteriorate once brought up to the surface.

While underwater, sulfur-reducing bacteria from the sea floor move into the wood and secrete hydrogen sulfide. This reacts with iron ions (rust) from items like nails or cannonballs, forming iron sulfide. This compound remains stable in environments that sport low levels of oxygen but binds with the gas to form acids that attack the wood.

In a paper being presented today at the 256th National Meeting & Exposition of the American Chemical Society (ACS), one team of researchers detail their efforts to keep wooden shipwrecks intact after recovery.

“This project began over a glass of wine with Eleanor Schofield, Ph.D., who is head of conservation at the Mary Rose Trust,” recalls Serena Corr, Ph.D., the project’s principal investigator.

“She was working on techniques to preserve the wood hull [of the Mary Rose] and assorted artifacts and needed a way to direct the treatment into the wood. We had been working with functional magnetic nanomaterials for applications in imaging, and we thought we might be able to apply this technology to the Mary Rose.”

Mary Rose.

Mary Rose in its specially-designed building at the Historic Dockyard in Portsmouth, United Kingdom.
Image via Wikimedia.

The Mary Rose was one of the first sailing ships built for war. Work on the wooden carrack (three-masted ship) began in 1510, and she was set to sea in July 1511. She remained one of the largest ships in the English navy for over three decades, during which she fought against the French, Scottish, and Brythonic navies — a task at which the Mary Rose excelled. The ship bristled with heavy cannons that popped out from gun-ports (which were cutting-edge technology at the time), and one of the first ships in the world capable of firing a full broadside.

Still, for reasons not yet clear, the ship sank in 1545 off the south coast of England. It was re-discovered in 1971 and recovered in 1982 by the Mary Rose Trust, along with over 19,000 artifacts and pieces of timber. The wreck helped provide a unique snapshot of seafaring and daily life in the Tudor period. It was displayed in a museum in Portsmouth, England, alongside the recovered artifacts.

Only 40% of the initial wooden structure survived the centuries underwater, and even this was rapidly degrading on the surface. So the Trust set out to preserve their invaluable wreck.

Corr’s goal was to avoid acid production by removing free iron ions from the wreck. She and her team at the University of Glasgow started by spraying the wood with cold water to keep it from drying out, which prevented further microbial activity, they explain. Afterward, they applied different types of polyethylene glycol (PEG) — a common polymer —  to the wreck. The PEG replaced water in the wood’s cells, forming a more robust outer layer.

The team, alongside researchers from the University of Warwick, are also working on a new family of magnetic nanoparticles to help in the conservation effort. They analyzed the sulfur species in the wood before the PEG treatment was applied, and then periodically as the ship dried.

This process will help the team design new targeted treatments to scrub sulfur compounds from the wood of the Mary Rose.

The next step, Schofield says, will be to use a nanocomposite material — based on magnetic iron oxide nanoparticles coated in active chemical agents — to remove these sulfur and iron ions. The nanoparticles will be applied directly to the wood and later guided through its pores to any particular areas using external magnetic fields. Such an approach should allow the team to completely remove the ions from the wood, they say.

“Conservators will have, for the first time, a state-of-the-art quantitative and restorative method for the safe and rapid treatment of wooden artifacts,” Corr says. “We plan to then transfer this technology to other materials recovered from the Mary Rose, such as textiles and leather.”

The paper “Magnetic nanocomposite materials for the archeological waterlogged wood conservation” has been presented today, Tuesday 21th August, at the 256th National Meeting & Exposition of the American Chemical Society (ACS).

Mining sulphur in an active volcano

Photo by Jean-Marie Hullot.

Whenever you think you have the worst job ever, you definitely should think about the sulphur miners from Eastern Java, the men who treat poisoned lungs, burns, scars and constant danger as part of their everyday living. Each day, a few hundred men go deep in the heart of the Ijen volcano, with the sole purpose of collecting yellow lumps of sulphur that solidify beside its acidic crater lake.

Photo by Aditya Suseno.

Just in case you’re wondering, sulphur has numerous uses, both inside Indonesia and outside: it is used to vulcanise rubber, make matches and fertiliser and even bleach sugar. Each day, they go up the mountain and gather 90 kg loads from the toxic lake, which they then have to carry back to a weighing station at the base of the volcano; and they do this several times per day.

Photo by Aditya Suseno.

“There are many big mountains but only one gives us the sulphur we need,” says Sulaiman, 31, who has mined the crater for 13 years.

Photo by Matt Paish.

Photo by Matt Paish.


About protection, you really shouldn’t – gas masks or gloves would be nothing less than a luxury for these men, who get paid around 10-15$ per day. The only protection from the deadly gas is clothing. But deadly gases aren’t the only thing they have to be wary of. In the past 40 years, 74 miners have died because of fumes that can come from fissures in the rock, more specifically hydrogen sulphide and sulphur dioxide gases, which are so concentrated they can even dissolve teeth, let alone the other parts of the body.

This practice wasn’t so uncommon 200 years ago, but by now it is mechanized in pretty much every part of the world. Clive Oppenheimer, of Cambridge University explains:

“Until the late 19th Century, there were sulphur mines in volcanic countries such as Italy, New Zealand, Chile and Indonesia.”

Photo by Aditya Suseno.

The work they do takes a harsh toll on their bodies; few of them live to grow old. However, their bodies have adapted, and most of them can hold their breath for several minutes; they also tend to develop amazing shoulder muscles from carrying baskets twice their bodyweight.

 

“Our families worry when we come here. They say working here can shorten your life,” says Hartomo, 34, a sulphur miner for 12 years. “I do it to feed my wife and kid. No other job pays this well,” adds Sulaiman.


Venus sulphur atmosphere holds warning for Earth

Despite the obvious differences, Venus has a lot in common with our Mother Earth, and we can learn a lot from our neighboring planet that can be really useful in the future; such is the case with the high-altitude layer of sulphur dioxide discovered by ESA’s Venus Express. This was a mystery that caused quite a stir in the scientific community, and was finally explained this week.

The importance it has for our planet is significant, because of the discussed plans of mitingating climate change that involved injecting our atmosphere with sulphur droplets. About the planet: Venus is covered by a sheet of acid clouds that block our view of the surface; the sheet forms at about 50 km from the planet surface, when sulphur dioxide from volcanoes combines with water to form sulphuric acid, one of the most corosive substances in the natural world. Any remaining sulphur dioxide is rapidly destroyed by solar radiation at 70 km, which is why the sulphur dioxide found at 90 km posed a total mystery; where could it come from ?

The answer came from a computer simulation conducted by Xi Zhang, California Institute of Technology, USA, and colleagues from America, France and Taiwan. They showed that some sulphuric acid droplets may evaporate at high altitude, freeing gaseous sulphuric acid that is then broken apart by sunlight, releasing sulphur dioxide gas.

“We had not expected the high-altitude sulphur layer, but now we can explain our measurements,” says Håkan Svedhem, ESA’s Venus Express Project Scientist. “However, the new findings also mean that the atmospheric sulphur cycle is more complicated than we thought.”

This yields a clear warning for us, that we have to broaden our understanding of the sulphur cycle before even dreaming to use it towards climate goals. Nobel prize winner Paul Crutzen is one of the people who openly supports injecting sulphur dioxide at 20 km above the Earth to fight climate change caused by emissions. However, this recent study of Venus shows that the results of injecting our atmosphere with such a substance may not be as successful as previously thought.

“We must study in great detail the potential consequences of such an artificial sulphur layer in the atmosphere of Earth,” says Jean-Loup Bertaux, Université de Versailles-Saint-Quentin, France, Principal Investigator of the SPICAV sensor on Venus Express. “Venus has an enormous layer of such droplets, so anything that we learn about those clouds is likely to be relevant to any geo-engineering of our own planet.”

This is one of the huge advantages we have from studying Venus: it allows us to experiment and observe what happens without actually experimenting on our world.