Greasy Sponge Slurps Up Oil

ORIGINAL: Chemical & Engineering News - ACS

By Erika Gebel

June 26, 2013

Materials Science: A chemical treatment makes a household sponge thirsty for oil instead of water

Waterproof Sponge. Water droplets rest on top of a superhydrophobic sponge coated in a thin layer of polypyrrole. Credit: Ind. Eng. Chem. Res.

Picking Up Petrol.
Researchers mixed petroleum with water in a petri dish (a)
and then added a superhydrophobic sponge (black, b).
After five minutes, the sponge had absorbed most of the oil from the water (c).
Credit: Ind. Eng. Chem. Res.

A sponge that can’t absorb a single drop of water may seem like a dud. But if it readily soaks up oil, it could help purify chemical syntheses or clean up oil spills on water. Researchers now report a simple chemical method for turning a household sponge into a water-blocking oil absorber (Ind. Eng. Chem. Res. 2013, DOI: 10.1021/ie400942t).

In response to oil spills on water, cleanup crews often turn to sorbent materials, such as wool, straw, cotton, and synthetic sponges, to separate oil from the water. Sponges are the best choice for the job, say Zhaozhu Zhang and colleagues at the Chinese Academy of Science. The materials can absorb a lot of liquid in a short time, and they can float. However, they suck up water as well as oil, so the sponges’ soaking capacity isn’t fully used to remove oil. To make the materials more efficient, Zhang and colleagues decided to make an oil-specific sponge.

The researchers purchased polyurethane sponges at a local furniture store and coated its entire surface with a thin layer of polypyrrole. This polymer is well known for being water-repellent and having a strong affinity for oil, says Paul L. Edmiston, a chemist at the College of Wooster, who was not involved in this study.

To prepare the sponge for its polypyrrole coating, the researchers first dipped it into ferric chloride and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES). They then put the PTES-coated sponge into a sealed chamber over a pool of volatile pyrrole, which vaporized and infused the sponge. The PTES helped the pyrrole adhere to the sponge surface. Meanwhile, the iron from the ferric chloride helped to catalyze the polymerization of the pyrrole into a thin coating over the sponge’s pores.

When the scientists added droplets of water to the surface of the revamped sponge, the water stayed in a bead and wasn’t absorbed. Droplets of oil, however, disappeared into the sponge immediately. The researchers also dipped the sponge into a variety of oils, including motor oil and soybean oil. The sponge sopped up more than 20 times its dry weight for each of the oils. The team tested how the sponge fared after reuse: They sopped up oil with the sponge and then wrung out the absorbed oil. After repeating those steps five times, the sponge could absorb at least 17 times its weight in oil.

Other groups have modified meshlike materials to absorb oil, Edmiston says. But he likes the idea of an oil-absorbing sponge, because it has “lots of room to pick up the oil.”

Edmiston is concerned that the cost of making these sponges would be prohibitive in the case of a large-scale oil-spill cleanup operation. Although the sponges themselves are cheap, the chemicals used in the treatment are expensive. The superhydrophobic sponges, though may find a place in certain industrial operations, Edmiston says, like removing hydrophobic solvents during chemical syntheses. Such small-scale applications would probably be the first uses for the revamped sponges, he says.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2013 American Chemical Society

Carnivorous Deep Sea Sponge Discovered Off Coast of California

ORIGINAL: SciTechDaily

November 12, 2012 by Range

Chondrocladia sp. Photo courtesy of MBARI and Craig McClain

The Monterey Bay Aquarium Research Institute (MBARI) has unveiled footage of a new species of carnivorous sea sponge. Chondrocladia lyra was discovered using deep-diving vessels by a team of researchers off the coast of California, at depths of 3,316 to 3,399 m.

The scientists published their findings in the journal Invertebrate Biology. 17 years ago, researchers at the Center of Oceanology at France’s Aix-Marseille University provided the first evidence of a species of deep-sea sponge living in a Mediterranean cave, at a shallow depth. It snared prey, like small fish and crustaceans, instead of absorbing bacteria and organic particles through their bodies, like most other sea sponges do.

This sponge was part of the Asbestopluma genus, and belonged to the Cladorhizidae family of carnivorous demosponges, a class which contains over 90% of the world’s sponges. Since then, circa 1995, 24 new species of cladorhizid sponges have been discovered. It has been difficult to study their behavior since their natural habitat is situated at such incredible depths.

MBARI has two ROVs and they’ve used these to study C. lyra. C. lyra can catch prey, envelop it in membrane and digest it whole. The vertical branches and horizontal stolons that make up the sponge are covered in barbed hooks and spines. A number of crustacean prey were passively ensnared onto these branches. Then, they were aggressively enclosed in a cavity to be dismembered into small, digestible particles.

C. lyra grows up to 37 cm in length, and are anchored to the sea-floor by a rhizoid, which resembles a root system. They can have 1 to 6 vanes, each supporting a number of equidistant vertical branches. The terminal balls produce spermatophores, which are released into the area in order to fertilize other harp sponges in the area. C. lyra also has an egg development area around the mid-point of the branches. Once the spermatophores make contact with it, these areas swell up as the eggs are fertilized and begin to mature.